diff --git a/config/build-plugins/plain-node-entry-guard.ts b/config/build-plugins/plain-node-entry-guard.ts
index 39033e04f01..bca58bf3b6c 100644
--- a/config/build-plugins/plain-node-entry-guard.ts
+++ b/config/build-plugins/plain-node-entry-guard.ts
@@ -18,7 +18,7 @@ export const CLI_MAIN_ENTRY_NAMES = [
   'orca-profiles/profile-index-store',
   'claude-accounts/keychain',
   'skills/bundled-skill-install/cli-entry',
-  'macos-tree-clone',
+  'filesystem/macos-tree-clone',
   'orcad/orcad-stale-lock-reclaim',
   'plugins/plugin-authoring-checks',
   ...[
diff --git a/config/electron-builder.config.cjs b/config/electron-builder.config.cjs
index 97631dcfc19..97b12132415 100644
--- a/config/electron-builder.config.cjs
+++ b/config/electron-builder.config.cjs
@@ -330,8 +330,8 @@ module.exports = {
     'out/main/gitlab/project-ref-parser.js',
     'out/main/grok/**',
     'out/main/hermes/**',
-    'out/main/asar-transparent-fs.js',
-    'out/main/macos-tree-clone.js',
+    'out/main/filesystem/asar-transparent-fs.js',
+    'out/main/filesystem/macos-tree-clone.js',
     'out/main/orca-profiles/profile-index-store.js',
     'out/main/persistence/profile-state/**',
     'out/main/plugins/plugin-authoring-checks.js',
diff --git a/config/scripts/ci-shard-timings.json b/config/scripts/ci-shard-timings.json
index 12d1578344c..6b8e46405c9 100644
--- a/config/scripts/ci-shard-timings.json
+++ b/config/scripts/ci-shard-timings.json
@@ -2478,14 +2478,14 @@
       "src/main/daemon/terminal-view-attribute-responder.test.ts": 54,
       "src/main/daemon/windows-conpty-warmup.test.ts": 51,
       "src/main/daemon/wsl-cold-restore-cwd.test.ts": 50,
-      "src/main/destination-serialized-local-rename.test.ts": 1392,
+      "src/main/filesystem/destination-serialized-local-rename.test.ts": 1392,
       "src/main/devin/hook-config-json.test.ts": 78,
       "src/main/devin/hook-service.test.ts": 159,
       "src/main/diagnostics/event-loop-delay-probe.test.ts": 84,
       "src/main/dsh/dsh-home-patch.test.ts": 57,
       "src/main/dsh/hook-service.test.ts": 124,
-      "src/main/durable-file-write-syscall-proof.test.ts": 73,
-      "src/main/durable-file-write.test.ts": 176,
+      "src/main/filesystem/durable-file-write-syscall-proof.test.ts": 73,
+      "src/main/filesystem/durable-file-write.test.ts": 176,
       "src/main/electron-updater-mac-staging-contract.test.ts": 125,
       "src/main/emulator/android/adb-devices.test.ts": 46,
       "src/main/emulator/android/android-avd-boot-identity.test.ts": 88,
@@ -2524,7 +2524,7 @@
       "src/main/ephemeral-vm/recipe-runner.test.ts": 460,
       "src/main/ephemeral-vm/runtime-service.test.ts": 870,
       "src/main/ephemeral-vm/runtime-ssh-cleanup.test.ts": 188,
-      "src/main/event-listener-fanout.test.ts": 52,
+      "src/main/runtime/events/event-listener-fanout.test.ts": 52,
       "src/main/execution-host-workspace-trust.test.ts": 232,
       "src/main/external-conversations/external-conversation-cancel-liveness.test.ts": 1752,
       "src/main/external-conversations/external-conversation-cancel-settlement.test.ts": 1601,
@@ -2536,7 +2536,7 @@
       "src/main/external-conversations/external-conversations-install.test.ts": 1687,
       "src/main/external-editors/external-editor-launch-process-host.test.ts": 215,
       "src/main/external-editors/external-editor-launch.test.ts": 151,
-      "src/main/file-transaction-lock.test.ts": 1047,
+      "src/main/filesystem/file-transaction-lock.test.ts": 1047,
       "src/main/fish-history-session.test.ts": 82,
       "src/main/fish-xdg-data-dirs-handoff.test.ts": 76,
       "src/main/folder-upgrade-worktree-path.test.ts": 251,
@@ -2923,8 +2923,8 @@
       "src/main/hooks-runner.test.ts": 314,
       "src/main/hooks-setup-runner-script.test.ts": 336,
       "src/main/hooks.test.ts": 474,
-      "src/main/host-checkout-removal.test.ts": 52,
-      "src/main/host-tree-removal-asar.electron.test.ts": 308,
+      "src/main/filesystem/host-checkout-removal.test.ts": 52,
+      "src/main/filesystem/host-tree-removal-asar.electron.test.ts": 308,
       "src/main/host/deferred-secret-protection-report.test.ts": 81,
       "src/main/host/electron-http-client.test.ts": 496,
       "src/main/host/electron-manual-redirect-fetch.test.ts": 52,
@@ -2936,8 +2936,8 @@
       "src/main/i18n/main-i18n-pre-init.test.ts": 50,
       "src/main/i18n/system-language.test.ts": 358,
       "src/main/media/image-file-signature.test.ts": 47,
-      "src/main/integration-state-file-cache.test.ts": 47,
-      "src/main/integration-token-file-cache.test.ts": 152,
+      "src/main/credentials/integration-state-file-cache.test.ts": 47,
+      "src/main/credentials/integration-token-file-cache.test.ts": 152,
       "src/main/ipc/account-sign-in-link-opener.test.ts": 128,
       "src/main/ipc/agent-hooks.test.ts": 736,
       "src/main/ipc/agent-pane-authority-ownership.test.ts": 47,
@@ -3584,7 +3584,7 @@
       "src/main/macos-permissions/macos-tcc-log-stream-orphans.test.ts": 110,
       "src/main/macos-permissions/macos-tcc-prompt-notice.test.ts": 82,
       "src/main/macos-permissions/macos-tcc-prompt-watch.test.ts": 77,
-      "src/main/macos-tree-clone.test.ts": 84,
+      "src/main/filesystem/macos-tree-clone.test.ts": 84,
       "src/main/macos-update-running-instances.integration.test.ts": 59,
       "src/main/managed-data-accounts/original-environment.test.ts": 209,
       "src/main/managed-data-accounts/profile-removal-recovery.test.ts": 479,
@@ -4860,8 +4860,8 @@
       "src/main/project-runtime-git-router-store.test.ts": 1818,
       "src/main/project-runtime-git-router.test.ts": 192,
       "src/main/project-runtime-read-git-options-opt-in.test.ts": 137,
-      "src/main/protected-secret-persistence-concurrency.test.ts": 68,
-      "src/main/protected-secret-persistence.test.ts": 53,
+      "src/main/credentials/protected-secret-persistence-concurrency.test.ts": 68,
+      "src/main/credentials/protected-secret-persistence.test.ts": 53,
       "src/main/provider-process/managed-provider-process-fallback-tree.test.ts": 150,
       "src/main/provider-process/managed-provider-process-root-only.test.ts": 164,
       "src/main/provider-process/managed-provider-process.test.ts": 185,
@@ -6479,7 +6479,7 @@
       "src/main/shell-startup-identity-scanner.test.ts": 39,
       "src/main/shell-startup-output-scanner.test.ts": 58,
       "src/main/shell-wrapper-content-address.test.ts": 49,
-      "src/main/sidecar-snapshot-file.test.ts": 65,
+      "src/main/filesystem/sidecar-snapshot-file.test.ts": 65,
       "src/main/skills/agent-skill-selection.test.ts": 103,
       "src/main/skills/antigravity-skill-discovery.test.ts": 128,
       "src/main/skills/bundled-skill-install/auto-update-eligibility.test.ts": 400,
@@ -7081,7 +7081,7 @@
       "src/main/windows/windows-pty-job.win32.test.ts": 84,
       "src/main/worker-thread-child-process/worker-thread-child-output-flow.test.ts": 158,
       "src/main/worker-thread-child-process/worker-thread-child-process.test.ts": 602,
-      "src/main/worker-thread-request-queue.test.ts": 83,
+      "src/main/worker-threads/worker-thread-request-queue.test.ts": 83,
       "src/main/workspaces/cleanup/workspace-cleanup-removal-snapshot-prune.test.ts": 60,
       "src/main/workspaces/cleanup/workspace-cleanup-scan-snapshot.test.ts": 160,
       "src/main/workspace-create-event-fields.test.ts": 265,
@@ -7231,7 +7231,7 @@
       "src/main/zcode/zcode-plan-api-key-store.test.ts": 89,
       "src/main/zcode/zcode-v2-personal-overlay-raw-json.test.ts": 259,
       "src/main/zcode/zcode-v2-plan-credentials.test.ts": 934,
-      "src/main/zod-schema-compilation.test.ts": 87,
+      "src/main/schema-validation/zod-schema-compilation.test.ts": 87,
       "src/packages/process-host/src/bounded-output-sink.test.ts": 75,
       "src/packages/process-host/src/close-process-registry.test.ts": 39,
       "src/packages/process-host/src/growing-byte-buffer.test.ts": 102,
diff --git a/config/scripts/orcad-terminal-smoke-change-scope.test.mjs b/config/scripts/orcad-terminal-smoke-change-scope.test.mjs
index 9272ed88648..e4ccff97d17 100644
--- a/config/scripts/orcad-terminal-smoke-change-scope.test.mjs
+++ b/config/scripts/orcad-terminal-smoke-change-scope.test.mjs
@@ -48,7 +48,7 @@ describe('the actual terminal smoke dependency graph', () => {
     ...Object.values(ORCAD_CHILD_ENTRY_POINTS),
     'src/main/runtime/orca-runtime.ts',
     'src/main/windows/windows-process-table.ts',
-    'src/main/worker-thread-entry-path.ts',
+    'src/main/worker-threads/worker-thread-entry-path.ts',
     'src/cli/index.ts',
     'config/scripts/runtime-serve-terminal-smoke.mjs',
     'config/scripts/build-orcad-node.mjs',
diff --git a/config/tsconfig.tc.web.json b/config/tsconfig.tc.web.json
index f6bfd010976..bc7273724b4 100644
--- a/config/tsconfig.tc.web.json
+++ b/config/tsconfig.tc.web.json
@@ -85,7 +85,7 @@
     "../src/main/persistence/applying-settings/ui-state-update.ts",
     "../src/main/persistence/applying-settings/ui-selection-normalization.ts",
     "../src/main/persistence/applying-settings/ui-interaction-merge.ts",
-    "../src/main/protected-secret-persistence.ts",
+    "../src/main/credentials/protected-secret-persistence.ts",
     "../src/main/startup/serve-desktop-activation.ts",
     "../src/main/startup/serve-mode-argv.ts",
     "../src/main/startup/single-instance-lock.ts",
diff --git a/src/cli/handlers/profile-state-recovery-admission.test.ts b/src/cli/handlers/profile-state-recovery-admission.test.ts
index cd641e0c5a6..c77b256e736 100644
--- a/src/cli/handlers/profile-state-recovery-admission.test.ts
+++ b/src/cli/handlers/profile-state-recovery-admission.test.ts
@@ -10,7 +10,7 @@ import {
 import { tmpdir } from 'node:os'
 import { join } from 'node:path'
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
-import * as durableFileWrite from '../../main/durable-file-write'
+import * as durableFileWrite from '../../main/filesystem/durable-file-write'
 import {
   acquireProfileStateMaintenance,
   acquireProfileStateRuntimeAdmission
diff --git a/src/cli/handlers/profile-state.test.ts b/src/cli/handlers/profile-state.test.ts
index 5121715a9ee..1ded91eaf79 100644
--- a/src/cli/handlers/profile-state.test.ts
+++ b/src/cli/handlers/profile-state.test.ts
@@ -3,7 +3,7 @@ import { tmpdir } from 'node:os'
 import { basename, join } from 'node:path'
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
 import type * as ProcessHostModule from '@orca/process-host'
-import * as durableFileWrite from '../../main/durable-file-write'
+import * as durableFileWrite from '../../main/filesystem/durable-file-write'
 import * as http1Marker from '../../main/startup/http1-compatibility-marker'
 import { readPersistedHttp1CompatibilityMode } from '../../main/startup/http1-compatibility-profile-state'
 import {
diff --git a/src/cli/runtime/serve-supervisor-relocation.ts b/src/cli/runtime/serve-supervisor-relocation.ts
index 995171c06a8..47403a74f51 100644
--- a/src/cli/runtime/serve-supervisor-relocation.ts
+++ b/src/cli/runtime/serve-supervisor-relocation.ts
@@ -3,7 +3,7 @@ import { createHash } from 'node:crypto'
 import { constants, readFileSync, rmSync, statSync } from 'node:fs'
 import { cp, mkdir, readdir, rename, rm, stat, writeFile } from 'node:fs/promises'
 import { basename, dirname, isAbsolute, join, relative, resolve } from 'node:path'
-import { cloneMacTree } from '../../main/macos-tree-clone'
+import { cloneMacTree } from '../../main/filesystem/macos-tree-clone'
 import { isProcessAlive } from '../../shared/serve-bundle-coordination'
 
 /** Relocated supervisors can no longer derive the app root from __dirname. */
diff --git a/src/main/acp/acp-session-events.ts b/src/main/acp/acp-session-events.ts
index 574cefb26eb..272b16545a5 100644
--- a/src/main/acp/acp-session-events.ts
+++ b/src/main/acp/acp-session-events.ts
@@ -1,5 +1,5 @@
 import { z } from 'zod'
-import { getCompiledSchema } from '../zod-schema-compilation'
+import { getCompiledSchema } from '../schema-validation/zod-schema-compilation'
 import {
   SessionNotificationSchema,
   type SessionNotification
diff --git a/src/main/agent-hooks/installer-utils.ts b/src/main/agent-hooks/installer-utils.ts
index ae178a6eedf..e581d6a68d3 100644
--- a/src/main/agent-hooks/installer-utils.ts
+++ b/src/main/agent-hooks/installer-utils.ts
@@ -14,7 +14,7 @@ import { randomUUID } from 'node:crypto'
 import type { AgentHookSource } from '../../shared/agent-hook-relay'
 import { grantDirAcl, isPermissionError } from '../win32-utils'
 import { resolveHooksJsonWritePath } from './hook-config-write-path'
-import { writeRollingFileBackup } from '../rolling-file-backup'
+import { writeRollingFileBackup } from '../filesystem/rolling-file-backup'
 import { renameOverLockedTarget } from './locked-executable-rename'
 import {
   getWindowsNativeHookAgent,
diff --git a/src/main/ai-vault/session-scanner-opencode-sqlite-process-client.ts b/src/main/ai-vault/session-scanner-opencode-sqlite-process-client.ts
index 122411eb7c1..9cad97e03be 100644
--- a/src/main/ai-vault/session-scanner-opencode-sqlite-process-client.ts
+++ b/src/main/ai-vault/session-scanner-opencode-sqlite-process-client.ts
@@ -1,7 +1,7 @@
 import { EventEmitter } from 'node:events'
 import { spawnProcess } from '@orca/process-host'
 import { waitForPromiseWithSignal } from '../../shared/abort-signal-reason'
-import type { WorkerRequestTransport } from '../lazy-worker-thread-host'
+import type { WorkerRequestTransport } from '../worker-threads/worker-thread-transport'
 import { OpenCodeSqliteWorkerClient } from './session-scanner-opencode-sqlite-worker-client'
 import {
   createOpenCodeSqliteLineDecoder,
diff --git a/src/main/ai-vault/session-scanner-opencode-sqlite-scan-scope.ts b/src/main/ai-vault/session-scanner-opencode-sqlite-scan-scope.ts
index e3a53a535b2..f123015f0b9 100644
--- a/src/main/ai-vault/session-scanner-opencode-sqlite-scan-scope.ts
+++ b/src/main/ai-vault/session-scanner-opencode-sqlite-scan-scope.ts
@@ -1,6 +1,6 @@
 import { AsyncLocalStorage } from 'node:async_hooks'
 import { throwIfSignalAborted } from '../../shared/abort-signal-reason'
-import type { WorkerThreadRequestOwner } from '../worker-thread-request-queue'
+import type { WorkerThreadRequestOwner } from '../worker-threads/worker-thread-request-queue'
 
 export const OPENCODE_SQLITE_SCAN_BUDGET_MS = 45_000
 
diff --git a/src/main/ai-vault/session-scanner-opencode-sqlite-worker-client.ts b/src/main/ai-vault/session-scanner-opencode-sqlite-worker-client.ts
index deb2b1eb3f1..b754f3ffa9e 100644
--- a/src/main/ai-vault/session-scanner-opencode-sqlite-worker-client.ts
+++ b/src/main/ai-vault/session-scanner-opencode-sqlite-worker-client.ts
@@ -1,6 +1,6 @@
-import type { WorkerThreadFactory } from '../lazy-worker-thread-host'
+import type { WorkerThreadFactory } from '../worker-threads/worker-thread-transport'
 import { aiVaultScanIssueText } from '../../shared/ai-vault-scan-issue-copy'
-import { WorkerThreadRequestQueue } from '../worker-thread-request-queue'
+import { WorkerThreadRequestQueue } from '../worker-threads/worker-thread-request-queue'
 import type { AiVaultScanIssue, AiVaultSession } from '../../shared/ai-vault-types'
 import type {
   OpenCodeNativeChatReadRequest,
diff --git a/src/main/ai-vault/session-scanner-service-entry-path.ts b/src/main/ai-vault/session-scanner-service-entry-path.ts
index ca9d0098212..64909fd33c1 100644
--- a/src/main/ai-vault/session-scanner-service-entry-path.ts
+++ b/src/main/ai-vault/session-scanner-service-entry-path.ts
@@ -3,7 +3,7 @@ import {
   getForkedChildEntryPath,
   resolveForkedChildEntryPath,
   resolveForkedChildEntryPathWithoutApp
-} from '../forked-child-entry-path'
+} from '../worker-threads/forked-child-entry-path'
 
 // orcad resolves this literal beside orcad.js; build-orcad.mjs emits it from ORCAD_CHILD_ENTRY_POINTS.
 export const AI_VAULT_SERVICE_ENTRY_FILENAME = 'session-scanner-service-entry.js'
diff --git a/src/main/antigravity/native-account-store.ts b/src/main/antigravity/native-account-store.ts
index cf269a6b0f6..9ab1f03fc8c 100644
--- a/src/main/antigravity/native-account-store.ts
+++ b/src/main/antigravity/native-account-store.ts
@@ -1,7 +1,7 @@
 import { existsSync, lstatSync, mkdirSync, readFileSync, statSync } from 'node:fs'
 import { dirname } from 'node:path'
 import { getSecretStore } from '../../shared/secret-store'
-import { writeCredentialFileAtomic } from '../integration-credential-file'
+import { writeCredentialFileAtomic } from '../credentials/integration-credential-file'
 import type { AntigravityAccountSummary } from '../../shared/antigravity-account-types'
 import { parseAntigravityNativeCredential } from './native-credential-codec'
 import { readPrivateWindowsFile } from '../../shared/secure-path-windows-acl'
diff --git a/src/main/antigravity/native-file-credentials.ts b/src/main/antigravity/native-file-credentials.ts
index 95abbdc9610..06b27323f3e 100644
--- a/src/main/antigravity/native-file-credentials.ts
+++ b/src/main/antigravity/native-file-credentials.ts
@@ -1,6 +1,6 @@
 import { existsSync, lstatSync, mkdirSync, readFileSync } from 'node:fs'
 import { dirname } from 'node:path'
-import { writeCredentialFileAtomic } from '../integration-credential-file'
+import { writeCredentialFileAtomic } from '../credentials/integration-credential-file'
 import { readPrivateWindowsFile } from '../../shared/secure-path-windows-acl'
 import { parseAntigravityNativeCredential } from './native-credential-codec'
 import type { AntigravityCredentialBackend } from './native-account-service'
diff --git a/src/main/ustar-entry-header.ts b/src/main/archive/ustar-entry-header.ts
similarity index 100%
rename from src/main/ustar-entry-header.ts
rename to src/main/archive/ustar-entry-header.ts
diff --git a/src/main/bitbucket/credential-store.ts b/src/main/bitbucket/credential-store.ts
index 37a1b963dcd..db7da5e3154 100644
--- a/src/main/bitbucket/credential-store.ts
+++ b/src/main/bitbucket/credential-store.ts
@@ -7,9 +7,9 @@ import {
   readStoredCredentialToken,
   writeCredentialFileAtomic,
   writeEncryptedCredential
-} from '../integration-credential-file'
+} from '../credentials/integration-credential-file'
 import type { BitbucketAuthMode } from '../../shared/bitbucket-credentials'
-import { readCredentialFileProtection } from '../credential-file-protection'
+import { readCredentialFileProtection } from '../credentials/credential-file-protection'
 import type { SecretAtRestProtection } from '../../shared/secret-at-rest-protection'
 
 // Plaintext display metadata lets status reads avoid keychain prompts.
diff --git a/src/main/browser/__mocks__/browser-session-registry-persistence-fixture.ts b/src/main/browser/__mocks__/browser-session-registry-persistence-fixture.ts
index e44a339904c..555f0cb2624 100644
--- a/src/main/browser/__mocks__/browser-session-registry-persistence-fixture.ts
+++ b/src/main/browser/__mocks__/browser-session-registry-persistence-fixture.ts
@@ -164,21 +164,26 @@ export function installModuleMocks(
     isScopedStagedCookieImport: vi.fn(() => false),
     removeCookieImportScopeMarker: vi.fn()
   }))
+  const renameFileWithWindowsRetryMock = vi.fn((source: string, target: string) => {
+    const sourceKey = fsKey(source)
+    const targetKey = fsKey(target)
+    if (!fsState.present.has(sourceKey)) {
+      throw new Error('ENOENT')
+    }
+    const value = fsState.files.get(sourceKey)
+    fsState.present.delete(sourceKey)
+    fsState.files.delete(sourceKey)
+    fsState.present.add(targetKey)
+    if (value !== undefined) {
+      fsState.files.set(targetKey, value)
+    }
+  })
+  vi.doMock('../../../shared/windows-retry-file-operations', async (importOriginal) => ({
+    ...(await importOriginal<Record<string, unknown>>()),
+    renameFileWithWindowsRetry: renameFileWithWindowsRetryMock
+  }))
   vi.doMock('../../codex-accounts/fs-utils', () => ({
-    renameFileWithWindowsRetry: vi.fn((source: string, target: string) => {
-      const sourceKey = fsKey(source)
-      const targetKey = fsKey(target)
-      if (!fsState.present.has(sourceKey)) {
-        throw new Error('ENOENT')
-      }
-      const value = fsState.files.get(sourceKey)
-      fsState.present.delete(sourceKey)
-      fsState.files.delete(sourceKey)
-      fsState.present.add(targetKey)
-      if (value !== undefined) {
-        fsState.files.set(targetKey, value)
-      }
-    }),
+    renameFileWithWindowsRetry: renameFileWithWindowsRetryMock,
     writeFileAtomically: vi.fn((pathValue: string, data: string) => {
       const key = fsKey(pathValue)
       fsState.files.set(key, data)
diff --git a/src/main/browser/browser-host-client-identity.ts b/src/main/browser/browser-host-client-identity.ts
index 6bf5f1c47a5..1c23f4a4768 100644
--- a/src/main/browser/browser-host-client-identity.ts
+++ b/src/main/browser/browser-host-client-identity.ts
@@ -1,7 +1,7 @@
 import { mkdirSync, readFileSync } from 'node:fs'
 import { randomUUID } from 'node:crypto'
 import { dirname, join } from 'node:path'
-import { durableWriteTempPath, writeFileDurableSync } from '../durable-file-write'
+import { durableWriteTempPath, writeFileDurableSync } from '../filesystem/durable-file-write'
 
 export const BROWSER_HOST_CLIENT_IDENTITY_FILE_NAME = 'browser-host-client-identity.json'
 
diff --git a/src/main/browser/browser-identity-mode-store.test.ts b/src/main/browser/browser-identity-mode-store.test.ts
index 2869d0ed115..46624901530 100644
--- a/src/main/browser/browser-identity-mode-store.test.ts
+++ b/src/main/browser/browser-identity-mode-store.test.ts
@@ -2,11 +2,11 @@ import { mkdtempSync, readdirSync, readFileSync, writeFileSync } from 'node:fs'
 import { tmpdir } from 'node:os'
 import { join } from 'node:path'
 import { beforeEach, describe, expect, it, vi } from 'vitest'
-import type * as DurableFileWrite from '../durable-file-write'
+import type * as DurableFileWrite from '../filesystem/durable-file-write'
 
 const mocks = vi.hoisted(() => ({ failWrite: false }))
 
-vi.mock('../durable-file-write', async (importOriginal) => {
+vi.mock('../filesystem/durable-file-write', async (importOriginal) => {
   const actual = await importOriginal<typeof DurableFileWrite>()
   return {
     ...actual,
diff --git a/src/main/browser/browser-identity-mode-store.ts b/src/main/browser/browser-identity-mode-store.ts
index 6e2086b261b..f259e972a3b 100644
--- a/src/main/browser/browser-identity-mode-store.ts
+++ b/src/main/browser/browser-identity-mode-store.ts
@@ -1,6 +1,6 @@
 import { randomUUID } from 'node:crypto'
 import { existsSync, readFileSync } from 'node:fs'
-import { durableWriteTempPath, writeFileDurableSync } from '../durable-file-write'
+import { durableWriteTempPath, writeFileDurableSync } from '../filesystem/durable-file-write'
 import type {
   BrowserIdentityModeSetResult,
   BrowserIdentityModeSnapshot,
diff --git a/src/main/browser/browser-profile-site-store.ts b/src/main/browser/browser-profile-site-store.ts
index 04602158536..3c292a60d86 100644
--- a/src/main/browser/browser-profile-site-store.ts
+++ b/src/main/browser/browser-profile-site-store.ts
@@ -1,7 +1,7 @@
 import { app } from 'electron'
 import { mkdirSync, readFileSync } from 'node:fs'
 import { dirname, join } from 'node:path'
-import { durableWriteTempPath, writeFileDurableSync } from '../durable-file-write'
+import { durableWriteTempPath, writeFileDurableSync } from '../filesystem/durable-file-write'
 
 export type BrowserProfileSiteStore<Entry> = {
   configure: (profileDirectory: string) => void
diff --git a/src/main/browser/browser-route-partition-binding-store.ts b/src/main/browser/browser-route-partition-binding-store.ts
index 5106def89bb..fae30ffee9d 100644
--- a/src/main/browser/browser-route-partition-binding-store.ts
+++ b/src/main/browser/browser-route-partition-binding-store.ts
@@ -1,7 +1,7 @@
 import { existsSync, mkdirSync, statSync } from 'node:fs'
 import { dirname, join } from 'node:path'
 import { grantDirAcl, isPermissionError } from '../win32-utils'
-import { durableWriteTempPath, writeFileDurableSync } from '../durable-file-write'
+import { durableWriteTempPath, writeFileDurableSync } from '../filesystem/durable-file-write'
 import {
   assertBinding,
   assertStorageScope,
diff --git a/src/main/browser/extensions/browser-extension-native-host-process.test.ts b/src/main/browser/extensions/browser-extension-native-host-process.test.ts
index 5ecd4c37355..58a5f6bf09d 100644
--- a/src/main/browser/extensions/browser-extension-native-host-process.test.ts
+++ b/src/main/browser/extensions/browser-extension-native-host-process.test.ts
@@ -12,7 +12,7 @@ import {
   type NativeHostConnection
 } from './browser-extension-native-host-process'
 
-vi.mock('../../forked-child-entry-path', () => ({
+vi.mock('../../worker-threads/forked-child-entry-path', () => ({
   getForkedChildEntryPath: (fileName: string) => join(root, fileName)
 }))
 
diff --git a/src/main/browser/extensions/browser-extension-native-host-process.ts b/src/main/browser/extensions/browser-extension-native-host-process.ts
index 34fd4bb623e..1067979fea3 100644
--- a/src/main/browser/extensions/browser-extension-native-host-process.ts
+++ b/src/main/browser/extensions/browser-extension-native-host-process.ts
@@ -6,7 +6,7 @@ import {
   forceTerminateProcessTree,
   signalProcessTree
 } from '@orca/process-host/process-tree-termination'
-import { getForkedChildEntryPath } from '../../forked-child-entry-path'
+import { getForkedChildEntryPath } from '../../worker-threads/forked-child-entry-path'
 import { NATIVE_HOST_ERRORS } from './browser-extension-native-host-errors'
 import {
   createNativeHostMessageReader,
diff --git a/src/main/browser/extensions/browser-extension-retired-profile-storage.ts b/src/main/browser/extensions/browser-extension-retired-profile-storage.ts
index 869119bf064..ffe18667301 100644
--- a/src/main/browser/extensions/browser-extension-retired-profile-storage.ts
+++ b/src/main/browser/extensions/browser-extension-retired-profile-storage.ts
@@ -1,7 +1,7 @@
 import { session } from 'electron'
 import { mkdirSync, readFileSync, rmSync } from 'node:fs'
 import { dirname, join } from 'node:path'
-import { durableWriteTempPath, writeFileDurableSync } from '../../durable-file-write'
+import { durableWriteTempPath, writeFileDurableSync } from '../../filesystem/durable-file-write'
 import { getBrowserExtensionInstallStore } from './browser-extension-install-store'
 import { clearBrowserExtensionProfileSessionData } from './browser-extension-data-removal'
 
diff --git a/src/main/browser/extensions/browser-extension-sync-storage-store.ts b/src/main/browser/extensions/browser-extension-sync-storage-store.ts
index 4401dc27bbe..37735085f48 100644
--- a/src/main/browser/extensions/browser-extension-sync-storage-store.ts
+++ b/src/main/browser/extensions/browser-extension-sync-storage-store.ts
@@ -2,7 +2,7 @@ import { app } from 'electron'
 import { mkdirSync, readFileSync, readdirSync, rmSync } from 'node:fs'
 import { join } from 'node:path'
 import { isChromeExtensionId } from '../../../shared/browser-extension-url'
-import { durableWriteTempPath, writeFileDurableSync } from '../../durable-file-write'
+import { durableWriteTempPath, writeFileDurableSync } from '../../filesystem/durable-file-write'
 import { getBrowserExtensionProfileDataDirectory } from './browser-extension-profile-data-directory'
 
 const SYNC_STORAGE_DIRECTORY = 'sync-storage'
diff --git a/src/main/claude-accounts/claude-profile-setup-worker.ts b/src/main/claude-accounts/claude-profile-setup-worker.ts
index af6b6f2d71b..4e86b6deb21 100644
--- a/src/main/claude-accounts/claude-profile-setup-worker.ts
+++ b/src/main/claude-accounts/claude-profile-setup-worker.ts
@@ -1,7 +1,10 @@
 import { existsSync } from 'node:fs'
 import { dirname, join } from 'node:path'
 import { Worker } from 'node:worker_threads'
-import { currentWorkerEntryLayout, resolveWorkerThreadEntryPath } from '../worker-thread-entry-path'
+import {
+  currentWorkerEntryLayout,
+  resolveWorkerThreadEntryPath
+} from '../worker-threads/worker-thread-entry-path'
 import type { ClaudeProfileDescriptor } from './claude-profile-paths'
 import type { ClaudeProfileSetupReport } from './claude-profile-setup'
 
diff --git a/src/main/claude/claude-rewind-transcript.ts b/src/main/claude/claude-rewind-transcript.ts
index dd2534c0f8a..96d86a589cd 100644
--- a/src/main/claude/claude-rewind-transcript.ts
+++ b/src/main/claude/claude-rewind-transcript.ts
@@ -3,7 +3,11 @@ import { createReadStream } from 'node:fs'
 import { rm } from 'node:fs/promises'
 import { dirname, join } from 'node:path'
 import type { AgentSessionRewindFork } from '../../shared/agent-session/lifecycle/agent-session-rewind'
-import { durableWriteTempPath, renameDurable, writeTempFileDurable } from '../durable-file-write'
+import {
+  durableWriteTempPath,
+  renameDurable,
+  writeTempFileDurable
+} from '../filesystem/durable-file-write'
 import { splitTranscriptStreamLines } from '../native-chat/transcript-stream-lines'
 import { loadClaudeAgentSdk } from './claude-stream-json-connection'
 
diff --git a/src/main/codex-accounts/async-file-rename.test.ts b/src/main/codex-accounts/async-file-rename.test.ts
index a453378a78d..bd5da38b0e2 100644
--- a/src/main/codex-accounts/async-file-rename.test.ts
+++ b/src/main/codex-accounts/async-file-rename.test.ts
@@ -3,7 +3,7 @@ import type * as NodeFsPromises from 'node:fs/promises'
 import { tmpdir } from 'node:os'
 import { join } from 'node:path'
 import { afterEach, expect, it, vi } from 'vitest'
-import { writeFileDurable, writeFileDurableIfCurrent } from '../durable-file-write'
+import { writeFileDurable, writeFileDurableIfCurrent } from '../filesystem/durable-file-write'
 
 const rename = vi.hoisted(() => vi.fn())
 vi.mock('node:fs/promises', async (importOriginal) => {
diff --git a/src/main/codex/codex-hook-hash-lookup.ts b/src/main/codex/codex-hook-hash-lookup.ts
index e5b9e168966..5aed6c7f847 100644
--- a/src/main/codex/codex-hook-hash-lookup.ts
+++ b/src/main/codex/codex-hook-hash-lookup.ts
@@ -1,5 +1,5 @@
 import { withTimeout } from '../../shared/promise-timeout-fallback'
-import { dedupeInFlightRun } from '../in-flight-run-dedupe'
+import { dedupeInFlightRun } from '../runtime/concurrency/in-flight-run-dedupe'
 import { resolveCodexCommand, resolveCodexCommandForSpawn } from '../codex-cli/command'
 import { getManagedCommand, getManagedScriptPath } from './codex-hook-definition'
 import {
diff --git a/src/main/codex/codex-hook-service-implementation.ts b/src/main/codex/codex-hook-service-implementation.ts
index 78d917b3bce..8cd63a54ccc 100644
--- a/src/main/codex/codex-hook-service-implementation.ts
+++ b/src/main/codex/codex-hook-service-implementation.ts
@@ -2,7 +2,7 @@ import { win32 as pathWin32 } from 'node:path'
 import type { SFTPWrapper } from 'ssh2'
 import type { AgentHookInstallStatus } from '../../shared/agent-hook-types'
 import { normalizeRuntimePathForComparison } from '../../shared/cross-platform-path'
-import { dedupeInFlightRun } from '../in-flight-run-dedupe'
+import { dedupeInFlightRun } from '../runtime/concurrency/in-flight-run-dedupe'
 import { refreshManagedScriptIfPresent } from '../agent-hooks/managed-hook-script-refresh'
 import { writeManagedScript } from '../agent-hooks/installer-utils'
 import { getOrcaManagedCodexHomePath } from './codex-home-paths'
diff --git a/src/main/codex/config-toml-atomic-write.ts b/src/main/codex/config-toml-atomic-write.ts
index 647f07b765f..47a538e9092 100644
--- a/src/main/codex/config-toml-atomic-write.ts
+++ b/src/main/codex/config-toml-atomic-write.ts
@@ -10,7 +10,7 @@ import {
 } from 'node:fs'
 import { dirname, join } from 'node:path'
 import { renameFileWithWindowsRetry } from '../codex-accounts/fs-utils'
-import { writeRollingFileBackup } from '../rolling-file-backup'
+import { writeRollingFileBackup } from '../filesystem/rolling-file-backup'
 
 export function writeTomlConfigAtomically(configPath: string, contents: string): void {
   const writePath = resolveTomlWritePath(configPath)
diff --git a/src/main/computer/sidecar-client.ts b/src/main/computer/sidecar-client.ts
index 7cadfcf5911..bfddc1766db 100644
--- a/src/main/computer/sidecar-client.ts
+++ b/src/main/computer/sidecar-client.ts
@@ -14,7 +14,7 @@ import {
 import { isComputerSidecarDiagnostic, logComputerDiagnostic } from './computer-sidecar-diagnostics'
 import { validateComputerSidecarPasteText } from './computer-sidecar-paste-validation'
 import { RuntimeClientError } from './runtime-client-error'
-import { getForkedChildEntryPath } from '../forked-child-entry-path'
+import { getForkedChildEntryPath } from '../worker-threads/forked-child-entry-path'
 
 // Bundled beside orcad.js on servers and under out/main on desktop.
 export const COMPUTER_SIDECAR_ENTRY_FILENAME = 'computer-sidecar.js'
diff --git a/src/main/import-source-validation.ts b/src/main/configuration-import/import-source-validation.ts
similarity index 100%
rename from src/main/import-source-validation.ts
rename to src/main/configuration-import/import-source-validation.ts
diff --git a/src/main/credential-file-protection.ts b/src/main/credentials/credential-file-protection.ts
similarity index 92%
rename from src/main/credential-file-protection.ts
rename to src/main/credentials/credential-file-protection.ts
index d5799ce52fd..7b1cba9d7d4 100644
--- a/src/main/credential-file-protection.ts
+++ b/src/main/credentials/credential-file-protection.ts
@@ -2,7 +2,7 @@ import { existsSync, readFileSync } from 'node:fs'
 import {
   classifyUnenvelopedCredential,
   type SecretAtRestProtection
-} from '../shared/secret-at-rest-protection'
+} from '../../shared/secret-at-rest-protection'
 
 /** Classify unenveloped token/ciphertext bytes without decrypting or prompting for the keychain. */
 export function readCredentialFileProtection(path: string): SecretAtRestProtection | null {
diff --git a/src/main/integration-credential-file.ts b/src/main/credentials/integration-credential-file.ts
similarity index 95%
rename from src/main/integration-credential-file.ts
rename to src/main/credentials/integration-credential-file.ts
index 2d424cf7574..56c3755cc90 100644
--- a/src/main/integration-credential-file.ts
+++ b/src/main/credentials/integration-credential-file.ts
@@ -9,13 +9,13 @@ import {
   unlinkSync,
   writeSync
 } from 'node:fs'
-import { getSecretStore } from '../shared/secret-store'
-import { fsyncFileSync } from '../shared/secure-file'
-import { writeRestrictedWindowsFile } from '../shared/secure-path-windows-acl'
+import { getSecretStore } from '../../shared/secret-store'
+import { fsyncFileSync } from '../../shared/secure-file'
+import { writeRestrictedWindowsFile } from '../../shared/secure-path-windows-acl'
 import {
   credentialDecryptionMessage,
   type IntegrationCredentialService
-} from '../shared/integration-credential-errors'
+} from '../../shared/integration-credential-errors'
 
 // Empty files mean no saved credential; keep status consistent with token reads.
 export function credentialFileHasContent(path: string): boolean {
diff --git a/src/main/integration-state-file-cache.test.ts b/src/main/credentials/integration-state-file-cache.test.ts
similarity index 100%
rename from src/main/integration-state-file-cache.test.ts
rename to src/main/credentials/integration-state-file-cache.test.ts
diff --git a/src/main/integration-state-file-cache.ts b/src/main/credentials/integration-state-file-cache.ts
similarity index 93%
rename from src/main/integration-state-file-cache.ts
rename to src/main/credentials/integration-state-file-cache.ts
index 9a735221410..ade024c7a96 100644
--- a/src/main/integration-state-file-cache.ts
+++ b/src/main/credentials/integration-state-file-cache.ts
@@ -1,5 +1,5 @@
 import { statSync } from 'node:fs'
-import { fileStatSignature } from './file-stat-signature'
+import { fileStatSignature } from '../filesystem/file-stat-signature'
 
 export type IntegrationStateFileCache<T> = {
   get(): T
diff --git a/src/main/integration-token-file-cache.test.ts b/src/main/credentials/integration-token-file-cache.test.ts
similarity index 98%
rename from src/main/integration-token-file-cache.test.ts
rename to src/main/credentials/integration-token-file-cache.test.ts
index c6b2390503a..3707dcae02b 100644
--- a/src/main/integration-token-file-cache.test.ts
+++ b/src/main/credentials/integration-token-file-cache.test.ts
@@ -2,7 +2,7 @@ import { mkdtempSync, rmSync, writeFileSync } from 'node:fs'
 import { tmpdir } from 'node:os'
 import { join } from 'node:path'
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
-import { setSecretStore } from '../shared/secret-store'
+import { setSecretStore } from '../../shared/secret-store'
 import { createIntegrationTokenFileCache } from './integration-token-file-cache'
 
 let directory = ''
diff --git a/src/main/integration-token-file-cache.ts b/src/main/credentials/integration-token-file-cache.ts
similarity index 95%
rename from src/main/integration-token-file-cache.ts
rename to src/main/credentials/integration-token-file-cache.ts
index 2bcfbc974f8..b625afdbd1a 100644
--- a/src/main/integration-token-file-cache.ts
+++ b/src/main/credentials/integration-token-file-cache.ts
@@ -1,5 +1,5 @@
 import { readFileSync } from 'node:fs'
-import type { IntegrationCredentialService } from '../shared/integration-credential-errors'
+import type { IntegrationCredentialService } from '../../shared/integration-credential-errors'
 import {
   CredentialDecryptionError,
   credentialFileHasContent,
diff --git a/src/main/protected-secret-persistence-concurrency.test.ts b/src/main/credentials/protected-secret-persistence-concurrency.test.ts
similarity index 99%
rename from src/main/protected-secret-persistence-concurrency.test.ts
rename to src/main/credentials/protected-secret-persistence-concurrency.test.ts
index 1b429cdaa8b..c4a1bbc1c68 100644
--- a/src/main/protected-secret-persistence-concurrency.test.ts
+++ b/src/main/credentials/protected-secret-persistence-concurrency.test.ts
@@ -1,5 +1,5 @@
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
-import { setSecretStore } from '../shared/secret-store'
+import { setSecretStore } from '../../shared/secret-store'
 import {
   ProtectedSecretPersistence,
   type ProtectedSecretRetentionUpdate
diff --git a/src/main/protected-secret-persistence.test.ts b/src/main/credentials/protected-secret-persistence.test.ts
similarity index 98%
rename from src/main/protected-secret-persistence.test.ts
rename to src/main/credentials/protected-secret-persistence.test.ts
index c0689dd004d..7a717a0a103 100644
--- a/src/main/protected-secret-persistence.test.ts
+++ b/src/main/credentials/protected-secret-persistence.test.ts
@@ -1,5 +1,5 @@
 import { beforeEach, describe, expect, it } from 'vitest'
-import { setSecretStore } from '../shared/secret-store'
+import { setSecretStore } from '../../shared/secret-store'
 
 const cipherState = { available: true }
 
diff --git a/src/main/protected-secret-persistence.ts b/src/main/credentials/protected-secret-persistence.ts
similarity index 99%
rename from src/main/protected-secret-persistence.ts
rename to src/main/credentials/protected-secret-persistence.ts
index c130bfc652b..486ead6e76b 100644
--- a/src/main/protected-secret-persistence.ts
+++ b/src/main/credentials/protected-secret-persistence.ts
@@ -1,4 +1,4 @@
-import { getSecretStore } from '../shared/secret-store'
+import { getSecretStore } from '../../shared/secret-store'
 
 export const PROTECTED_SECRET_SLOT = {
   opencodeSessionCookie: 'settings.opencodeSessionCookie',
diff --git a/src/main/daemon/automatic-work-run-marker-store.ts b/src/main/daemon/automatic-work-run-marker-store.ts
index bc8b9810ff9..9766756798e 100644
--- a/src/main/daemon/automatic-work-run-marker-store.ts
+++ b/src/main/daemon/automatic-work-run-marker-store.ts
@@ -1,6 +1,6 @@
 import { readFileSync } from 'node:fs'
 import { uptime } from 'node:os'
-import { durableWriteTempPath, writeFileDurableSync } from '../durable-file-write'
+import { durableWriteTempPath, writeFileDurableSync } from '../filesystem/durable-file-write'
 import type { AutomaticWorkMode } from '../../shared/host-spawn-admission'
 import {
   decideStartupAutomaticWorkMode,
diff --git a/src/main/daemon/daemon-host-file-hash-cache.ts b/src/main/daemon/daemon-host-file-hash-cache.ts
index 3808aed3116..d6712977cbf 100644
--- a/src/main/daemon/daemon-host-file-hash-cache.ts
+++ b/src/main/daemon/daemon-host-file-hash-cache.ts
@@ -1,8 +1,8 @@
 import { createHash } from 'node:crypto'
 import { readFileSync, statSync } from 'node:fs'
-import { fileStatSignature } from '../file-stat-signature'
+import { fileStatSignature } from '../filesystem/file-stat-signature'
 
-export { fileStatSignature as daemonHostFileStatSignature } from '../file-stat-signature'
+export { fileStatSignature as daemonHostFileStatSignature } from '../filesystem/file-stat-signature'
 
 // Metadata validation avoids rereading unchanged daemon code on the main thread.
 const cachedHashes = new Map<string, { signature: string; sha256: string }>()
diff --git a/src/main/daemon/history-manager.test.ts b/src/main/daemon/history-manager.test.ts
index 9f51452aea2..6126739310f 100644
--- a/src/main/daemon/history-manager.test.ts
+++ b/src/main/daemon/history-manager.test.ts
@@ -12,7 +12,7 @@ import {
   writeFileSync
 } from 'node:fs'
 import { HistoryManager } from './history-manager'
-import * as hostTreeRemoval from '../host-tree-removal'
+import * as hostTreeRemoval from '../filesystem/host-tree-removal'
 import { flushPendingSessionTreeRemovals } from './terminal-history-session-tombstone'
 import type { TerminalSnapshot, TerminalModes } from './types'
 import { getHistorySessionDirName } from './history-paths'
diff --git a/src/main/daemon/legacy-restore-records.ts b/src/main/daemon/legacy-restore-records.ts
index 6ea099e5edd..637b6b0d3ab 100644
--- a/src/main/daemon/legacy-restore-records.ts
+++ b/src/main/daemon/legacy-restore-records.ts
@@ -1,5 +1,5 @@
 import { readFileSync } from 'node:fs'
-import { durableWriteTempPath, writeFileDurableSync } from '../durable-file-write'
+import { durableWriteTempPath, writeFileDurableSync } from '../filesystem/durable-file-write'
 import type { LegacyRestoreRecord } from '../../shared/host-spawn-admission'
 import { DEFAULT_MAX_HOST_TERMINALS } from './host-terminal-ledger'
 
diff --git a/src/main/daemon/macos-daemon-bundle-retirement.ts b/src/main/daemon/macos-daemon-bundle-retirement.ts
index 7641785b2e0..ad98de8341b 100644
--- a/src/main/daemon/macos-daemon-bundle-retirement.ts
+++ b/src/main/daemon/macos-daemon-bundle-retirement.ts
@@ -1,7 +1,7 @@
 import { readdir } from 'node:fs/promises'
 import { join } from 'node:path'
 import { runProcess } from '@orca/process-host'
-import { rm } from '../asar-transparent-fs'
+import { rm } from '../filesystem/asar-transparent-fs'
 import { macDaemonCopyBundlePath } from './macos-daemon-bundle'
 
 const LSREGISTER =
diff --git a/src/main/daemon/macos-daemon-bundle.ts b/src/main/daemon/macos-daemon-bundle.ts
index 83238e85984..a532a483839 100644
--- a/src/main/daemon/macos-daemon-bundle.ts
+++ b/src/main/daemon/macos-daemon-bundle.ts
@@ -2,8 +2,8 @@ import { existsSync } from 'node:fs'
 import { mkdir, mkdtemp, realpath, rename } from 'node:fs/promises'
 import { dirname, isAbsolute, join, resolve } from 'node:path'
 import { runProcess } from '@orca/process-host'
-import { cloneMacTree } from '../macos-tree-clone'
-import { rm } from '../asar-transparent-fs'
+import { cloneMacTree } from '../filesystem/macos-tree-clone'
+import { rm } from '../filesystem/asar-transparent-fs'
 import { ensurePrivateDir } from './daemon-private-file-modes'
 import { inspectMacProcessCodeIdentity } from './daemon-mac-code-identity'
 
diff --git a/src/main/daemon/macos-daemon-launchd.ts b/src/main/daemon/macos-daemon-launchd.ts
index 16eba1d7c94..31e7566bc56 100644
--- a/src/main/daemon/macos-daemon-launchd.ts
+++ b/src/main/daemon/macos-daemon-launchd.ts
@@ -5,7 +5,7 @@ import { getAppEnvironment } from '../../shared/app-environment'
 import { LOCAL_BUILD_COMPATIBILITY_CONTRACT } from '../../shared/local-build-compatibility-contract'
 import { NODE_RUNTIME_DARWIN_MINIMUM_OS } from '../../shared/node-runtime-pin'
 import { runProcess } from '@orca/process-host'
-import { rm } from '../asar-transparent-fs'
+import { rm } from '../filesystem/asar-transparent-fs'
 import { compareDottedVersions } from '../orcad/native-host-abi'
 import { DaemonClient } from './client'
 import { DaemonEndpointOwnershipError, holdDaemonAdoptionLease } from './daemon-endpoint-adoption'
diff --git a/src/main/daemon/terminal-history-session-tombstone-retry.test.ts b/src/main/daemon/terminal-history-session-tombstone-retry.test.ts
index f8a00603d39..650359d5bd7 100644
--- a/src/main/daemon/terminal-history-session-tombstone-retry.test.ts
+++ b/src/main/daemon/terminal-history-session-tombstone-retry.test.ts
@@ -7,7 +7,7 @@ const { removeHostTreeMock } = vi.hoisted(() => ({
   removeHostTreeMock: vi.fn<(dir: string) => Promise<void>>()
 }))
 
-vi.mock('../host-tree-removal', () => ({
+vi.mock('../filesystem/host-tree-removal', () => ({
   removeHostTree: removeHostTreeMock
 }))
 
diff --git a/src/main/daemon/terminal-history-session-tombstone.ts b/src/main/daemon/terminal-history-session-tombstone.ts
index 84feb11887e..6cd6155a034 100644
--- a/src/main/daemon/terminal-history-session-tombstone.ts
+++ b/src/main/daemon/terminal-history-session-tombstone.ts
@@ -3,7 +3,7 @@
 import { randomUUID } from 'node:crypto'
 import { existsSync, readdirSync, renameSync } from 'node:fs'
 import { join } from 'node:path'
-import { removeHostTree } from '../host-tree-removal'
+import { removeHostTree } from '../filesystem/host-tree-removal'
 import { ensurePrivateDir } from './daemon-private-file-modes'
 import { getHistorySessionDirName } from './history-paths'
 import { getTerminalHistoryQuarantineOwnerDir } from './terminal-history-recovery-quarantine'
diff --git a/src/main/asar-transparent-fs.ts b/src/main/filesystem/asar-transparent-fs.ts
similarity index 100%
rename from src/main/asar-transparent-fs.ts
rename to src/main/filesystem/asar-transparent-fs.ts
diff --git a/src/main/destination-serialized-local-rename.test.ts b/src/main/filesystem/destination-serialized-local-rename.test.ts
similarity index 97%
rename from src/main/destination-serialized-local-rename.test.ts
rename to src/main/filesystem/destination-serialized-local-rename.test.ts
index 1169dfcd898..27aafde4cd9 100644
--- a/src/main/destination-serialized-local-rename.test.ts
+++ b/src/main/filesystem/destination-serialized-local-rename.test.ts
@@ -28,8 +28,8 @@ vi.mock('fs/promises', async () => {
 })
 
 import { renameLocalPathSerializedByDestination } from './destination-serialized-local-rename'
-import { registerFilesystemMutationHandlers } from './ipc/filesystem/filesystem-mutations'
-import { RuntimeFileCommands } from './runtime/orca-runtime-files'
+import { registerFilesystemMutationHandlers } from '../ipc/filesystem/filesystem-mutations'
+import { RuntimeFileCommands } from '../runtime/orca-runtime-files'
 
 const REPO_PATH = path.resolve('/workspace/repo')
 const store = {
diff --git a/src/main/destination-serialized-local-rename.ts b/src/main/filesystem/destination-serialized-local-rename.ts
similarity index 91%
rename from src/main/destination-serialized-local-rename.ts
rename to src/main/filesystem/destination-serialized-local-rename.ts
index f605815ed56..076ed784770 100644
--- a/src/main/destination-serialized-local-rename.ts
+++ b/src/main/filesystem/destination-serialized-local-rename.ts
@@ -1,7 +1,7 @@
 import { realpath, rename } from 'node:fs/promises'
 import { dirname, normalize } from 'node:path'
-import { assertNoClobberRenameDestinationAvailable } from '../shared/filesystem-rename-collision'
-import { windowsFsPath } from './wsl/wsl-unc-drive-fs-path'
+import { assertNoClobberRenameDestinationAvailable } from '../../shared/filesystem-rename-collision'
+import { windowsFsPath } from '../wsl/wsl-unc-drive-fs-path'
 
 // Parent-scoped serialization covers Unicode aliases without guessing filesystem collation.
 const pendingRenamesByParent = new Map<string, Promise<void>>()
diff --git a/src/main/durable-file-write-syscall-proof.test.ts b/src/main/filesystem/durable-file-write-syscall-proof.test.ts
similarity index 100%
rename from src/main/durable-file-write-syscall-proof.test.ts
rename to src/main/filesystem/durable-file-write-syscall-proof.test.ts
diff --git a/src/main/durable-file-write.test.ts b/src/main/filesystem/durable-file-write.test.ts
similarity index 100%
rename from src/main/durable-file-write.test.ts
rename to src/main/filesystem/durable-file-write.test.ts
diff --git a/src/main/durable-file-write.ts b/src/main/filesystem/durable-file-write.ts
similarity index 97%
rename from src/main/durable-file-write.ts
rename to src/main/filesystem/durable-file-write.ts
index 047e7df3263..f8ebfeb7dad 100644
--- a/src/main/durable-file-write.ts
+++ b/src/main/filesystem/durable-file-write.ts
@@ -3,11 +3,11 @@
 import { closeSync, fsyncSync, openSync, rmSync, writeFileSync } from 'node:fs'
 import { open, readdir, rm, stat } from 'node:fs/promises'
 import { basename, dirname, join } from 'node:path'
+import { publishFileWithoutOverwrite } from '../codex-accounts/fs-utils'
 import {
-  publishFileWithoutOverwrite,
   renameFileWithWindowsRetry,
   renameFileWithWindowsRetryAsync
-} from './codex-accounts/fs-utils'
+} from '../../shared/windows-retry-file-operations'
 
 /** Persist directory changes where supported; Windows and some filesystems reject directory fsync. */
 async function syncDirectory(directory: string): Promise<void> {
diff --git a/src/main/file-stat-signature.ts b/src/main/filesystem/file-stat-signature.ts
similarity index 100%
rename from src/main/file-stat-signature.ts
rename to src/main/filesystem/file-stat-signature.ts
diff --git a/src/main/file-transaction-lock.test.ts b/src/main/filesystem/file-transaction-lock.test.ts
similarity index 100%
rename from src/main/file-transaction-lock.test.ts
rename to src/main/filesystem/file-transaction-lock.test.ts
diff --git a/src/main/file-transaction-lock.ts b/src/main/filesystem/file-transaction-lock.ts
similarity index 100%
rename from src/main/file-transaction-lock.ts
rename to src/main/filesystem/file-transaction-lock.ts
diff --git a/src/main/home-path-expansion.ts b/src/main/filesystem/home-path-expansion.ts
similarity index 100%
rename from src/main/home-path-expansion.ts
rename to src/main/filesystem/home-path-expansion.ts
diff --git a/src/main/host-checkout-removal.test.ts b/src/main/filesystem/host-checkout-removal.test.ts
similarity index 100%
rename from src/main/host-checkout-removal.test.ts
rename to src/main/filesystem/host-checkout-removal.test.ts
diff --git a/src/main/host-tree-removal-asar.electron.test.ts b/src/main/filesystem/host-tree-removal-asar.electron.test.ts
similarity index 96%
rename from src/main/host-tree-removal-asar.electron.test.ts
rename to src/main/filesystem/host-tree-removal-asar.electron.test.ts
index 647c354c1fb..65988e1dc0d 100644
--- a/src/main/host-tree-removal-asar.electron.test.ts
+++ b/src/main/filesystem/host-tree-removal-asar.electron.test.ts
@@ -11,7 +11,7 @@ import { createRequire, isBuiltin } from 'node:module'
 import { tmpdir } from 'node:os'
 import { dirname, join } from 'node:path'
 import { afterAll, describe, expect, it } from 'vitest'
-import { removeTreeSync } from '../shared/windows-transient-lock-removal'
+import { removeTreeSync } from '../../shared/windows-transient-lock-removal'
 
 /** Electron’s asar fs shim makes recursive removal fail; plain Node cannot reproduce it. */
 const requireFromTest = createRequire(import.meta.url)
@@ -67,7 +67,7 @@ async function bundleHostTreeRemoval(outFile: string): Promise<void> {
       minify: false,
       ssr: true,
       rollupOptions: {
-        input: 'src/main/host-tree-removal.ts',
+        input: 'src/main/filesystem/host-tree-removal.ts',
         // Match production externals: externalizing original-fs here could hide a bundling regression.
         output: { format: 'cjs' },
         external: (id: string) => isBuiltin(id) || id === 'electron' || id.startsWith('electron/')
diff --git a/src/main/host-tree-removal.ts b/src/main/filesystem/host-tree-removal.ts
similarity index 91%
rename from src/main/host-tree-removal.ts
rename to src/main/filesystem/host-tree-removal.ts
index 54f7776bcd1..563bee871cc 100644
--- a/src/main/host-tree-removal.ts
+++ b/src/main/filesystem/host-tree-removal.ts
@@ -1,13 +1,13 @@
 // Host deletion needs bounded Windows lock retries and unpatched fs for Electron’s .asar handling.
 
-import { getErrorCode } from './git/worktree-operation-options'
-import { unregisteredFolderRefusal } from '../shared/worktree/removal'
+import { getErrorCode } from '../git/worktree-operation-options'
+import { unregisteredFolderRefusal } from '../../shared/worktree/removal'
 import { join, win32 } from 'node:path'
 import { lstat, readdir, rm, rmdir, unlink } from './asar-transparent-fs'
-import { isWindowsAbsolutePathLike } from '../shared/cross-platform-path'
-import { isWslUncPath } from '../shared/wsl-paths'
-import { stripWin32LongPathPrefix } from '../shared/windows-path-access'
-import { removeTree } from '../shared/windows-transient-lock-removal'
+import { isWindowsAbsolutePathLike } from '../../shared/cross-platform-path'
+import { isWslUncPath } from '../../shared/wsl-paths'
+import { stripWin32LongPathPrefix } from '../../shared/windows-path-access'
+import { removeTree } from '../../shared/windows-transient-lock-removal'
 
 /** Convert a native host filesystem path to the Win32 long-path namespace. */
 export function toHostFilesystemPath(targetPath: string): string {
diff --git a/src/main/macos-tree-clone.test.ts b/src/main/filesystem/macos-tree-clone.test.ts
similarity index 100%
rename from src/main/macos-tree-clone.test.ts
rename to src/main/filesystem/macos-tree-clone.test.ts
diff --git a/src/main/macos-tree-clone.ts b/src/main/filesystem/macos-tree-clone.ts
similarity index 100%
rename from src/main/macos-tree-clone.ts
rename to src/main/filesystem/macos-tree-clone.ts
diff --git a/src/main/rolling-file-backup.ts b/src/main/filesystem/rolling-file-backup.ts
similarity index 87%
rename from src/main/rolling-file-backup.ts
rename to src/main/filesystem/rolling-file-backup.ts
index 9817e3fd362..18b242f4ce7 100644
--- a/src/main/rolling-file-backup.ts
+++ b/src/main/filesystem/rolling-file-backup.ts
@@ -1,6 +1,9 @@
 import { randomUUID } from 'node:crypto'
 import { lstatSync, rmSync } from 'node:fs'
-import { copyFileWithWindowsRetry, renameFileWithWindowsRetry } from './codex-accounts/fs-utils'
+import {
+  copyFileWithWindowsRetry,
+  renameFileWithWindowsRetry
+} from '../../shared/windows-retry-file-operations'
 
 export function writeRollingFileBackup(sourcePath: string, backupPath: string): void {
   try {
diff --git a/src/main/sidecar-snapshot-file.test.ts b/src/main/filesystem/sidecar-snapshot-file.test.ts
similarity index 100%
rename from src/main/sidecar-snapshot-file.test.ts
rename to src/main/filesystem/sidecar-snapshot-file.test.ts
diff --git a/src/main/sidecar-snapshot-file.ts b/src/main/filesystem/sidecar-snapshot-file.ts
similarity index 100%
rename from src/main/sidecar-snapshot-file.ts
rename to src/main/filesystem/sidecar-snapshot-file.ts
diff --git a/src/main/foreign-sqlite-readers/foreign-sqlite-reader-client-worker-lifecycle.test.ts b/src/main/foreign-sqlite-readers/foreign-sqlite-reader-client-worker-lifecycle.test.ts
index c2d6c856a47..bc640744b95 100644
--- a/src/main/foreign-sqlite-readers/foreign-sqlite-reader-client-worker-lifecycle.test.ts
+++ b/src/main/foreign-sqlite-readers/foreign-sqlite-reader-client-worker-lifecycle.test.ts
@@ -1,7 +1,7 @@
 import { EventEmitter } from 'node:events'
 import { Worker } from 'node:worker_threads'
 import { afterEach, describe, expect, it } from 'vitest'
-import type { WorkerRequestTransport } from '../lazy-worker-thread-host'
+import type { WorkerRequestTransport } from '../worker-threads/worker-thread-transport'
 import { ForeignSqliteReaderClient } from './foreign-sqlite-reader-client'
 
 const FAILURE = { status: 'error', error: 'Unable to read the Cursor desktop login' }
diff --git a/src/main/foreign-sqlite-readers/foreign-sqlite-reader-client.test.ts b/src/main/foreign-sqlite-readers/foreign-sqlite-reader-client.test.ts
index 668fdf20282..d08c911c0f9 100644
--- a/src/main/foreign-sqlite-readers/foreign-sqlite-reader-client.test.ts
+++ b/src/main/foreign-sqlite-readers/foreign-sqlite-reader-client.test.ts
@@ -1,5 +1,5 @@
 import { describe, expect, it, vi } from 'vitest'
-import type { WorkerRequestTransport } from '../lazy-worker-thread-host'
+import type { WorkerRequestTransport } from '../worker-threads/worker-thread-transport'
 import { ForeignSqliteReaderClient, ForeignSqliteReaderLane } from './foreign-sqlite-reader-client'
 import type { ForeignSqliteReaderRequest } from './foreign-sqlite-reader-protocol'
 
diff --git a/src/main/foreign-sqlite-readers/foreign-sqlite-reader-client.ts b/src/main/foreign-sqlite-readers/foreign-sqlite-reader-client.ts
index 223c474b1c7..72ff491f825 100644
--- a/src/main/foreign-sqlite-readers/foreign-sqlite-reader-client.ts
+++ b/src/main/foreign-sqlite-readers/foreign-sqlite-reader-client.ts
@@ -1,5 +1,5 @@
-import type { WorkerThreadFactory } from '../lazy-worker-thread-host'
-import { WorkerThreadRequestQueue } from '../worker-thread-request-queue'
+import type { WorkerThreadFactory } from '../worker-threads/worker-thread-transport'
+import { WorkerThreadRequestQueue } from '../worker-threads/worker-thread-request-queue'
 import {
   cursorProfileReadFailure,
   parseCursorProfileReadResult,
diff --git a/src/main/foreign-sqlite-readers/foreign-sqlite-reader-entry-path.ts b/src/main/foreign-sqlite-readers/foreign-sqlite-reader-entry-path.ts
index 8e4ed7499be..8b015759a29 100644
--- a/src/main/foreign-sqlite-readers/foreign-sqlite-reader-entry-path.ts
+++ b/src/main/foreign-sqlite-readers/foreign-sqlite-reader-entry-path.ts
@@ -1,6 +1,9 @@
 import { existsSync } from 'node:fs'
 import { join } from 'node:path'
-import { resolveWorkerThreadEntryPath, type WorkerEntryLayout } from '../worker-thread-entry-path'
+import {
+  resolveWorkerThreadEntryPath,
+  type WorkerEntryLayout
+} from '../worker-threads/worker-thread-entry-path'
 
 // Electron-free: the OpenCode scanner reaches this from plain-Node processes too.
 
diff --git a/src/main/foreign-sqlite-readers/foreign-sqlite-reader-spawn.ts b/src/main/foreign-sqlite-readers/foreign-sqlite-reader-spawn.ts
index 7ad4dd43427..0b1d5984d27 100644
--- a/src/main/foreign-sqlite-readers/foreign-sqlite-reader-spawn.ts
+++ b/src/main/foreign-sqlite-readers/foreign-sqlite-reader-spawn.ts
@@ -1,7 +1,7 @@
 import { existsSync } from 'node:fs'
 import { stat } from 'node:fs/promises'
 import { Worker } from 'node:worker_threads'
-import { currentWorkerEntryLayout } from '../worker-thread-entry-path'
+import { currentWorkerEntryLayout } from '../worker-threads/worker-thread-entry-path'
 import type { CursorDesktopProfileReadResult } from './cursor-profile-result'
 import { ForeignSqliteReaderClient } from './foreign-sqlite-reader-client'
 import { resolveForeignSqliteReaderEntryPath } from './foreign-sqlite-reader-entry-path'
diff --git a/src/main/git/windows-worktree-removal.ts b/src/main/git/windows-worktree-removal.ts
index 6159ec044bc..6cdc02b2787 100644
--- a/src/main/git/windows-worktree-removal.ts
+++ b/src/main/git/windows-worktree-removal.ts
@@ -1,7 +1,7 @@
 import { join, resolve } from 'node:path'
 import { readFile } from 'node:fs/promises'
-import { lstat, readdir } from '../asar-transparent-fs'
-import { removeHostCheckout } from '../host-tree-removal'
+import { lstat, readdir } from '../filesystem/asar-transparent-fs'
+import { removeHostCheckout } from '../filesystem/host-tree-removal'
 import { parseWslPath } from '../wsl'
 import { CLIENT_REMOVAL_HOME } from '../worktree-removal-home-guard'
 import {
diff --git a/src/main/git/worktree-preparation-add.ts b/src/main/git/worktree-preparation-add.ts
index bcbeb4dae8f..3bc606fd893 100644
--- a/src/main/git/worktree-preparation-add.ts
+++ b/src/main/git/worktree-preparation-add.ts
@@ -2,7 +2,7 @@ import { lstat } from 'node:fs/promises'
 import { isUnsupportedWorktreeAddLockReasonError } from '../../shared/git-worktree-command-capabilities'
 import { resolveWorktreeHostPath } from '../../shared/git-metadata-path'
 import { windowsLongPathGitArgs } from '../../shared/windows-long-path-git-args'
-import { toHostFilesystemPath } from '../host-tree-removal'
+import { toHostFilesystemPath } from '../filesystem/host-tree-removal'
 import { withLocalGitCapabilityCacheForExecution } from './git-capability-state'
 import { gitExecFileAsync } from './runner'
 import {
diff --git a/src/main/git/worktree-preparation-discard.ts b/src/main/git/worktree-preparation-discard.ts
index 902f098fc86..0af4524b0c3 100644
--- a/src/main/git/worktree-preparation-discard.ts
+++ b/src/main/git/worktree-preparation-discard.ts
@@ -4,7 +4,7 @@ import { waitForPromiseWithSignal } from '../../shared/abort-signal-reason'
 import { resolveWorktreeHostPath } from '../../shared/git-metadata-path'
 import { findLinkedWorktreeGitDirectory } from '../../shared/git-worktree-admin'
 import { windowsLongPathGitArgs } from '../../shared/windows-long-path-git-args'
-import { toHostFilesystemPath } from '../host-tree-removal'
+import { toHostFilesystemPath } from '../filesystem/host-tree-removal'
 import { gitExecFileAsync } from './runner'
 import {
   getErrorCode,
diff --git a/src/main/git/worktree-preparation-lock.test.ts b/src/main/git/worktree-preparation-lock.test.ts
index 4bb2b0cadd8..843e0e74059 100644
--- a/src/main/git/worktree-preparation-lock.test.ts
+++ b/src/main/git/worktree-preparation-lock.test.ts
@@ -1,7 +1,7 @@
 import { beforeEach, describe, expect, it, vi } from 'vitest'
 import { tmpdir } from 'node:os'
 import { join } from 'node:path'
-import { toHostFilesystemPath } from '../host-tree-removal'
+import { toHostFilesystemPath } from '../filesystem/host-tree-removal'
 import type * as FilePromises from 'node:fs/promises'
 
 const mocks = vi.hoisted(() => ({
diff --git a/src/main/git/worktree-preparation-lock.ts b/src/main/git/worktree-preparation-lock.ts
index d0ea67935a7..6c93e325a5a 100644
--- a/src/main/git/worktree-preparation-lock.ts
+++ b/src/main/git/worktree-preparation-lock.ts
@@ -2,7 +2,7 @@ import { readFile, unlink, writeFile } from 'node:fs/promises'
 import { posix, win32 } from 'node:path'
 import { isWindowsAbsolutePathLike } from '../../shared/cross-platform-path'
 import { resolveGitMetadataPath, type GitMetadataPathOptions } from '../../shared/git-metadata-path'
-import { toHostFilesystemPath } from '../host-tree-removal'
+import { toHostFilesystemPath } from '../filesystem/host-tree-removal'
 import { gitExecFileAsync } from './runner'
 import {
   getErrorCode,
diff --git a/src/main/git/worktree-removal-real-git.test.ts b/src/main/git/worktree-removal-real-git.test.ts
index 3d134be5bf2..3e58311b1d7 100644
--- a/src/main/git/worktree-removal-real-git.test.ts
+++ b/src/main/git/worktree-removal-real-git.test.ts
@@ -7,7 +7,7 @@ import { join } from 'node:path'
 import { performance } from 'node:perf_hooks'
 import { promisify } from 'node:util'
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
-import * as nativeFs from '../asar-transparent-fs'
+import * as nativeFs from '../filesystem/asar-transparent-fs'
 import * as diskFs from 'node:fs/promises'
 import * as runner from './runner'
 import {
diff --git a/src/main/git/worktree-removal.ts b/src/main/git/worktree-removal.ts
index 2a6c9de2925..97bdb811a48 100644
--- a/src/main/git/worktree-removal.ts
+++ b/src/main/git/worktree-removal.ts
@@ -3,7 +3,7 @@ import { pruneGitWorktrees } from './worktree-prune-guard'
 import type { RemoveWorktreeResult } from '../../shared/worktree/create-types'
 import { assertWorktreeUnlockedForRemoval } from '../../shared/worktree/removal'
 import { windowsLongPathGitArgs } from '../../shared/windows-long-path-git-args'
-import { removeHostTree } from '../host-tree-removal'
+import { removeHostTree } from '../filesystem/host-tree-removal'
 import { withSpan } from '../observability/tracer'
 import { parseWslPath } from '../wsl'
 import { gitExecFileAsync } from './runner'
diff --git a/src/main/github/conflict-summary-cache.ts b/src/main/github/conflict-summary-cache.ts
index 02ac3214906..38da459528b 100644
--- a/src/main/github/conflict-summary-cache.ts
+++ b/src/main/github/conflict-summary-cache.ts
@@ -1,5 +1,5 @@
 import type { PRConflictSummary } from '../../shared/github/pull-request-types'
-import { dedupeInFlightRun } from '../in-flight-run-dedupe'
+import { dedupeInFlightRun } from '../runtime/concurrency/in-flight-run-dedupe'
 
 // Throttle even manual refreshes to one base fetch per minute; GitHub recomputes mergeability asynchronously.
 export const CONFLICT_SUMMARY_BASE_FETCH_WINDOW_MS = 60_000
diff --git a/src/main/ipc/command-path-directory-worker-client.ts b/src/main/ipc/command-path-directory-worker-client.ts
index 63ad146799d..c01373f05d9 100644
--- a/src/main/ipc/command-path-directory-worker-client.ts
+++ b/src/main/ipc/command-path-directory-worker-client.ts
@@ -1,7 +1,11 @@
 import { existsSync } from 'node:fs'
 import { Worker } from 'node:worker_threads'
-import { LazyWorkerThreadHost, type WorkerThreadFactory } from '../lazy-worker-thread-host'
-import { currentWorkerEntryLayout, resolveWorkerThreadEntryPath } from '../worker-thread-entry-path'
+import { LazyWorkerThreadHost } from '../worker-threads/lazy-worker-thread-host'
+import type { WorkerThreadFactory } from '../worker-threads/worker-thread-transport'
+import {
+  currentWorkerEntryLayout,
+  resolveWorkerThreadEntryPath
+} from '../worker-threads/worker-thread-entry-path'
 import type {
   DetectionDirectoryRequest,
   DetectionDirectoryResponse
diff --git a/src/main/ipc/filesystem/filesystem-download-handlers.ts b/src/main/ipc/filesystem/filesystem-download-handlers.ts
index 15ef200f1d1..64fe3b7fa00 100644
--- a/src/main/ipc/filesystem/filesystem-download-handlers.ts
+++ b/src/main/ipc/filesystem/filesystem-download-handlers.ts
@@ -2,7 +2,7 @@ import { BrowserWindow, dialog, ipcMain } from 'electron'
 import { randomUUID } from 'node:crypto'
 import { open, writeFile } from 'node:fs/promises'
 import { SshHostNotServedError } from '../../providers/ssh-host-not-served-error'
-import { sanitizeLocalDownloadFilename } from '../../local-download-filename'
+import { sanitizeLocalDownloadFilename } from './local-download-filename'
 import { abortWhenRendererGone } from '../renderer-lifetime-abort'
 import type { FilesystemHandlerContext } from './filesystem-handler-context'
 import {
diff --git a/src/main/ipc/filesystem/filesystem-mutations.ts b/src/main/ipc/filesystem/filesystem-mutations.ts
index 7a7cb2199cc..1587c94b0aa 100644
--- a/src/main/ipc/filesystem/filesystem-mutations.ts
+++ b/src/main/ipc/filesystem/filesystem-mutations.ts
@@ -13,7 +13,7 @@ import { SshHostNotServedError } from '../../providers/ssh-host-not-served-error
 import { resolveLocalDroppedPathsForAgent } from '../dropped-path-resolution'
 import type { SshMutationExpectation } from '../../../shared/ssh-types'
 import { assertSshMutationExpectation } from '../../ssh/connection/ssh-connection-generation'
-import { renameLocalPathSerializedByDestination } from '../../destination-serialized-local-rename'
+import { renameLocalPathSerializedByDestination } from '../../filesystem/destination-serialized-local-rename'
 import { assertNotExists, rethrowWithUserMessage } from './filesystem-create-path-guards'
 import type {
   ImportItemResult,
diff --git a/src/main/ipc/filesystem/local-disk-write-precondition.ts b/src/main/ipc/filesystem/local-disk-write-precondition.ts
index 95c5b8f4888..ae048276a29 100644
--- a/src/main/ipc/filesystem/local-disk-write-precondition.ts
+++ b/src/main/ipc/filesystem/local-disk-write-precondition.ts
@@ -17,7 +17,7 @@ import {
 import { readlink, realpath, stat, writeFile } from 'node:fs/promises'
 import { basename, dirname, join, normalize, resolve } from 'node:path'
 import { runKeyedSerializedOperation } from '../../cli/keyed-promise-queue'
-import { serializedParentDirectoryKey } from '../../destination-serialized-local-rename'
+import { serializedParentDirectoryKey } from '../../filesystem/destination-serialized-local-rename'
 import { windowsFsPath } from '../../wsl/wsl-unc-drive-fs-path'
 import {
   assertLocalWriteTargetIsRegularFile,
diff --git a/src/main/local-download-filename.ts b/src/main/ipc/filesystem/local-download-filename.ts
similarity index 100%
rename from src/main/local-download-filename.ts
rename to src/main/ipc/filesystem/local-download-filename.ts
diff --git a/src/main/ipc/filesystem/watcher-process/parcel-watcher-entry-path.ts b/src/main/ipc/filesystem/watcher-process/parcel-watcher-entry-path.ts
index e5d5082f91b..fd77cc07673 100644
--- a/src/main/ipc/filesystem/watcher-process/parcel-watcher-entry-path.ts
+++ b/src/main/ipc/filesystem/watcher-process/parcel-watcher-entry-path.ts
@@ -3,7 +3,7 @@ import {
   getForkedChildEntryPath,
   resolveForkedChildEntryPath,
   resolveForkedChildEntryPathWithoutApp
-} from '../../../forked-child-entry-path'
+} from '../../../worker-threads/forked-child-entry-path'
 
 const WATCHER_ENTRY_FILENAME = 'parcel-watcher-process-entry.js'
 
diff --git a/src/main/ipc/jira/issue-summary-generation.ts b/src/main/ipc/jira/issue-summary-generation.ts
index 322dc597b90..07d1df0a864 100644
--- a/src/main/ipc/jira/issue-summary-generation.ts
+++ b/src/main/ipc/jira/issue-summary-generation.ts
@@ -9,7 +9,7 @@ import {
   cancelJiraIssueSummaryRequest,
   generateJiraIssueSummaryRequest
 } from '../../text-generation/jira-issue-summary-requests'
-import { addFanoutListener } from '../../event-listener-fanout'
+import { addFanoutListener } from '../../runtime/events/event-listener-fanout'
 
 export function registerJiraIssueSummaryGenerationHandlers(
   store: Pick<Store, 'getSettings'>,
diff --git a/src/main/ipc/renderer-lifetime-abort.ts b/src/main/ipc/renderer-lifetime-abort.ts
index de552274dd3..6be925c5cfd 100644
--- a/src/main/ipc/renderer-lifetime-abort.ts
+++ b/src/main/ipc/renderer-lifetime-abort.ts
@@ -1,4 +1,4 @@
-import { addFanoutListeners, type FanoutEventSource } from '../event-listener-fanout'
+import { addFanoutListeners, type FanoutEventSource } from '../runtime/events/event-listener-fanout'
 
 export type RendererLifetimeSender = FanoutEventSource
 
diff --git a/src/main/ipc/runtime-ssh-access-handlers.ts b/src/main/ipc/runtime-ssh-access-handlers.ts
index 30d5502e30a..ffd24857a12 100644
--- a/src/main/ipc/runtime-ssh-access-handlers.ts
+++ b/src/main/ipc/runtime-ssh-access-handlers.ts
@@ -4,7 +4,7 @@ import {
   RuntimeSshAccessUnlinkRequestSchema
 } from '../../shared/runtime-ssh-access'
 import { linkRuntimeSshAccess, unlinkRuntimeSshAccess } from '../ssh/runtime-ssh-access'
-import { addFanoutListener } from '../event-listener-fanout'
+import { addFanoutListener } from '../runtime/events/event-listener-fanout'
 
 export function registerRuntimeSshAccessHandlers(options: {
   getUserDataPath: () => string
diff --git a/src/main/ipc/worktrees-removal-recovery.test.ts b/src/main/ipc/worktrees-removal-recovery.test.ts
index 45fcd245894..dfcdb711068 100644
--- a/src/main/ipc/worktrees-removal-recovery.test.ts
+++ b/src/main/ipc/worktrees-removal-recovery.test.ts
@@ -6,7 +6,7 @@ import * as gitRunner from '../git/runner'
 import { removeWorktree } from '../git/worktree'
 import { removeWorktree as removeNativeWorktree } from '../git/worktree-removal'
 import { readTranslatedWorktreeGraph } from '../git/worktree-list-reader'
-import { toHostFilesystemPath } from '../host-tree-removal'
+import { toHostFilesystemPath } from '../filesystem/host-tree-removal'
 import { removeTree } from '../../shared/windows-transient-lock-removal'
 import * as scopedRootsInvalidation from './registered-worktree-roots-scoped-invalidation'
 import * as authorizedRootsCache from './registered-worktree-roots-cache'
diff --git a/src/main/jira/client.ts b/src/main/jira/client.ts
index 9c673f3f301..6d54f5ce8fd 100644
--- a/src/main/jira/client.ts
+++ b/src/main/jira/client.ts
@@ -1,5 +1,5 @@
 import { taskProviderFailure } from '../../shared/task-provider-failure'
-import { CredentialDecryptionError } from '../integration-credential-file'
+import { CredentialDecryptionError } from '../credentials/integration-credential-file'
 import type {
   JiraAuthType,
   JiraConnectArgs,
diff --git a/src/main/jira/site-credential-store.ts b/src/main/jira/site-credential-store.ts
index d72162ce1c7..47fda409e1a 100644
--- a/src/main/jira/site-credential-store.ts
+++ b/src/main/jira/site-credential-store.ts
@@ -1,13 +1,13 @@
 import { existsSync, mkdirSync, readFileSync, unlinkSync, writeFileSync } from 'node:fs'
 import { homedir } from 'node:os'
 import { join } from 'node:path'
-import { writeEncryptedCredential } from '../integration-credential-file'
-import { readCredentialFileProtection } from '../credential-file-protection'
+import { writeEncryptedCredential } from '../credentials/integration-credential-file'
+import { readCredentialFileProtection } from '../credentials/credential-file-protection'
 import type { SecretAtRestProtection } from '../../shared/secret-at-rest-protection'
 import type { JiraSite, JiraSiteSelection } from '../../shared/jira/jira-types'
-import { createIntegrationStateFileCache } from '../integration-state-file-cache'
+import { createIntegrationStateFileCache } from '../credentials/integration-state-file-cache'
 import { isJiraGatewayBaseUrl } from './gateway-base-url'
-import { createIntegrationTokenFileCache } from '../integration-token-file-cache'
+import { createIntegrationTokenFileCache } from '../credentials/integration-token-file-cache'
 
 export type JiraSiteFile = {
   version: 1
diff --git a/src/main/linear/client.ts b/src/main/linear/client.ts
index 103087bd8b9..6656ebcdc25 100644
--- a/src/main/linear/client.ts
+++ b/src/main/linear/client.ts
@@ -25,7 +25,7 @@ import {
   saveWorkspaceToken,
   getWorkspaceTokenProtection
 } from './linear-token-store'
-import { CredentialDecryptionError } from '../integration-credential-file'
+import { CredentialDecryptionError } from '../credentials/integration-credential-file'
 import type {
   LinearConnectionStatus,
   LinearViewer,
diff --git a/src/main/linear/linear-token-store.ts b/src/main/linear/linear-token-store.ts
index cedf13f5f0f..e8e52a21979 100644
--- a/src/main/linear/linear-token-store.ts
+++ b/src/main/linear/linear-token-store.ts
@@ -1,5 +1,5 @@
 import { unlinkSync } from 'node:fs'
-import { writeEncryptedCredential } from '../integration-credential-file'
+import { writeEncryptedCredential } from '../credentials/integration-credential-file'
 import {
   LEGACY_WORKSPACE_ID,
   ensureOrcaDir,
@@ -23,7 +23,7 @@ import {
   workspaceTokenFileCache
 } from './linear-workspace-registry'
 import type { LinearWorkspace } from '../../shared/linear/workspace-types'
-import { readCredentialFileProtection } from '../credential-file-protection'
+import { readCredentialFileProtection } from '../credentials/credential-file-protection'
 import type { SecretAtRestProtection } from '../../shared/secret-at-rest-protection'
 
 export function saveWorkspaceToken(workspaceId: string, apiKey: string): void {
diff --git a/src/main/linear/linear-workspace-registry.ts b/src/main/linear/linear-workspace-registry.ts
index 1e95def7256..f4d4ec959b6 100644
--- a/src/main/linear/linear-workspace-registry.ts
+++ b/src/main/linear/linear-workspace-registry.ts
@@ -13,8 +13,8 @@ import {
   type LinearWorkspaceFile
 } from './linear-workspace-record'
 import type { LinearWorkspace } from '../../shared/linear/workspace-types'
-import { createIntegrationStateFileCache } from '../integration-state-file-cache'
-import { createIntegrationTokenFileCache } from '../integration-token-file-cache'
+import { createIntegrationStateFileCache } from '../credentials/integration-state-file-cache'
+import { createIntegrationTokenFileCache } from '../credentials/integration-token-file-cache'
 
 export const workspaceTokenFileCache = createIntegrationTokenFileCache({
   service: 'Linear',
diff --git a/src/main/local-worktree-filesystem.ts b/src/main/local-worktree-filesystem.ts
index f66c2548648..6bfbcc3ed97 100644
--- a/src/main/local-worktree-filesystem.ts
+++ b/src/main/local-worktree-filesystem.ts
@@ -3,13 +3,13 @@ import { runProcess } from '@orca/process-host'
 import { lstat, stat, readFile, realpath } from 'node:fs/promises'
 import { buildWslExecArgs } from '../shared/wsl-login-shell-command'
 import { quotePosixShell } from '../shared/shell-argument-quoting'
-import { removeHostTree } from './host-tree-removal'
+import { removeHostTree } from './filesystem/host-tree-removal'
 import { toLinuxPath } from './wsl'
 import { resolveWslInteropSpawnCwd } from './wsl-interop-spawn-directory'
 import { describeWslProcessFailure } from './wsl/wsl-process-failure'
 import type { WorktreeProofAccess } from './worktree-orphan-gitdir-proof'
 
-export { toHostFilesystemPath, toHostRemovalPath } from './host-tree-removal'
+export { toHostFilesystemPath, toHostRemovalPath } from './filesystem/host-tree-removal'
 
 export type LocalWorktreeFilesystemOptions = {
   wslDistro?: string
diff --git a/src/main/local-worktree-removal-recovery.test.ts b/src/main/local-worktree-removal-recovery.test.ts
index b63c8cce37c..b8fc85e505e 100644
--- a/src/main/local-worktree-removal-recovery.test.ts
+++ b/src/main/local-worktree-removal-recovery.test.ts
@@ -17,7 +17,7 @@ vi.mock('./local-worktree-filesystem', () => ({
   removeLocalWorktreePath: removeLocalWorktreePathMock
 }))
 
-vi.mock('./asar-transparent-fs', () => ({ rm: hostRmMock }))
+vi.mock('./filesystem/asar-transparent-fs', () => ({ rm: hostRmMock }))
 
 vi.mock('./git/worktree', () => ({
   listWorktreesStrict: listWorktreesStrictMock
diff --git a/src/main/managed-data-accounts/profile-removal.ts b/src/main/managed-data-accounts/profile-removal.ts
index a944533f725..65778d1d8b1 100644
--- a/src/main/managed-data-accounts/profile-removal.ts
+++ b/src/main/managed-data-accounts/profile-removal.ts
@@ -2,7 +2,7 @@ import { existsSync, lstatSync, mkdirSync, readFileSync, renameSync, rmSync } fr
 import { readdir } from 'node:fs/promises'
 import { dirname, join } from 'node:path'
 import { z } from 'zod'
-import { removeHostTree } from '../host-tree-removal'
+import { removeHostTree } from '../filesystem/host-tree-removal'
 import type {
   ManagedDataAccountProvider,
   ManagedDataAccountsState
diff --git a/src/main/native-chat/agent-session-journal/journal-checkpoint-owner.ts b/src/main/native-chat/agent-session-journal/journal-checkpoint-owner.ts
index 6d0026f77b8..a801d8c8f30 100644
--- a/src/main/native-chat/agent-session-journal/journal-checkpoint-owner.ts
+++ b/src/main/native-chat/agent-session-journal/journal-checkpoint-owner.ts
@@ -1,7 +1,7 @@
 import { setTimeout, clearTimeout } from 'node:timers'
 import { Worker } from 'node:worker_threads'
 import type Database from '../../sqlite/sync-database'
-import type { WorkerRequestTransport } from '../../worker-thread-transport'
+import type { WorkerRequestTransport } from '../../worker-threads/worker-thread-transport'
 import { journalCheckpointWorkerSource } from './journal-checkpoint-worker-source'
 import { JOURNAL_SIZE_LIMIT_BYTES } from './journal-database'
 
diff --git a/src/main/orcad-migration-export-holds.test.ts b/src/main/orcad-migration-export-holds.test.ts
index 294d40326e5..3ee29a4d68a 100644
--- a/src/main/orcad-migration-export-holds.test.ts
+++ b/src/main/orcad-migration-export-holds.test.ts
@@ -4,7 +4,7 @@ import { join } from 'node:path'
 import { afterEach, describe, expect, it, vi } from 'vitest'
 import { getDefaultWorkspaceSession } from '../shared/constants'
 import type { WorkspaceSessionState } from '../shared/workspace-session-state-types'
-import { writeFileDurableSync } from './durable-file-write'
+import { writeFileDurableSync } from './filesystem/durable-file-write'
 import {
   getTerminalScrollbackSnapshotPath,
   readTerminalScrollbackStoredBytesSync,
diff --git a/src/main/orcad/orcad-forked-child-paths.test.ts b/src/main/orcad/orcad-forked-child-paths.test.ts
index a7093c54a33..cbc9bff0880 100644
--- a/src/main/orcad/orcad-forked-child-paths.test.ts
+++ b/src/main/orcad/orcad-forked-child-paths.test.ts
@@ -12,7 +12,7 @@ import {
   FOREIGN_SQLITE_READER_ENTRY_FILENAME,
   resolveForeignSqliteReaderEntryPath
 } from '../foreign-sqlite-readers/foreign-sqlite-reader-entry-path'
-import { currentWorkerEntryLayout } from '../worker-thread-entry-path'
+import { currentWorkerEntryLayout } from '../worker-threads/worker-thread-entry-path'
 import { installOrcadHostAdapters } from './orcad-host-adapters'
 
 // Compose real adapters and deployment paths: isolated resolver tests missed nonexistent fork targets.
diff --git a/src/main/orcad/orcad-plaintext-credential-migration.test.ts b/src/main/orcad/orcad-plaintext-credential-migration.test.ts
index 441db6d032e..658dec396bb 100644
--- a/src/main/orcad/orcad-plaintext-credential-migration.test.ts
+++ b/src/main/orcad/orcad-plaintext-credential-migration.test.ts
@@ -4,7 +4,7 @@ import { join } from 'node:path'
 import { afterEach, beforeEach, describe, expect, it } from 'vitest'
 import type { SecretStore } from '../../shared/secret-store'
 import { _resetSecretStoreForTests, setSecretStore } from '../../shared/secret-store'
-import { readStoredCredentialToken } from '../integration-credential-file'
+import { readStoredCredentialToken } from '../credentials/integration-credential-file'
 import { migratePlaintextCredentials } from './orcad-plaintext-credential-migration'
 import { orcadSecretStateFileName } from './orcad-secret-key-record'
 import { createOrcadSecretStore } from './orcad-secret-store'
diff --git a/src/main/orcad/orcad-plaintext-credential-migration.ts b/src/main/orcad/orcad-plaintext-credential-migration.ts
index 18d15e54018..7a3e6067f08 100644
--- a/src/main/orcad/orcad-plaintext-credential-migration.ts
+++ b/src/main/orcad/orcad-plaintext-credential-migration.ts
@@ -5,7 +5,7 @@ import { join } from 'node:path'
 import type { SecretStore } from '../../shared/secret-store'
 import { classifyUnenvelopedCredential } from '../../shared/secret-at-rest-protection'
 import { hardenExistingSecureFile, writeSecureFile } from '../../shared/secure-file'
-import { writeCredentialFileAtomic } from '../integration-credential-file'
+import { writeCredentialFileAtomic } from '../credentials/integration-credential-file'
 import {
   getWorkspaceTokenDir,
   getWorkspaceTokenPath,
diff --git a/src/main/orcad/orcad-secret-key-resolution.ts b/src/main/orcad/orcad-secret-key-resolution.ts
index 9e1e2ee5773..c15125474be 100644
--- a/src/main/orcad/orcad-secret-key-resolution.ts
+++ b/src/main/orcad/orcad-secret-key-resolution.ts
@@ -1,7 +1,7 @@
 import { randomBytes } from 'node:crypto'
 import { join } from 'node:path'
 import process from 'node:process'
-import { withFileTransactionLock } from '../file-transaction-lock'
+import { withFileTransactionLock } from '../filesystem/file-transaction-lock'
 import { profileStateAccessMachineIdentity } from '../persistence/profile-state/profile-state-access-identity'
 import {
   resolveOrcadLegacyKeyringReader,
diff --git a/src/main/orcad/orcad-secret-store.test.ts b/src/main/orcad/orcad-secret-store.test.ts
index be7039ed846..f2366adbc29 100644
--- a/src/main/orcad/orcad-secret-store.test.ts
+++ b/src/main/orcad/orcad-secret-store.test.ts
@@ -17,7 +17,10 @@ import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
 import { credentialDecryptionMessage } from '../../shared/integration-credential-errors'
 import { classifyUnenvelopedCredential } from '../../shared/secret-at-rest-protection'
 import { _resetSecretStoreForTests, setSecretStore } from '../../shared/secret-store'
-import { readStoredCredentialToken, writeEncryptedCredential } from '../integration-credential-file'
+import {
+  readStoredCredentialToken,
+  writeEncryptedCredential
+} from '../credentials/integration-credential-file'
 import type { OrcadLegacyKeyLookup, OrcadLegacyKeyringReader } from './orcad-legacy-keyring-key'
 import { orcadSecretStateFileName } from './orcad-secret-key-record'
 import {
diff --git a/src/main/persistence/applying-settings/settings-update-effects.ts b/src/main/persistence/applying-settings/settings-update-effects.ts
index c96e98c6501..a8952620608 100644
--- a/src/main/persistence/applying-settings/settings-update-effects.ts
+++ b/src/main/persistence/applying-settings/settings-update-effects.ts
@@ -1,5 +1,5 @@
 import type { GlobalSettings } from '../../../shared/global-settings-types'
-import { PROTECTED_SECRET_SLOT } from '../../protected-secret-persistence'
+import { PROTECTED_SECRET_SLOT } from '../../credentials/protected-secret-persistence'
 import { retireAtRestCommandSettings } from '../../native-chat/agent-session-wire/at-rest-command-context'
 import { createAgentModelCatalogSettingsExpiry } from '../../native-chat/agent-model-catalog/agent-model-catalog-account-expiry'
 import { agentModelCatalogStore } from '../../native-chat/agent-model-catalog/agent-model-catalog-store'
diff --git a/src/main/persistence/applying-settings/settings-update.ts b/src/main/persistence/applying-settings/settings-update.ts
index 9ae7ef8d042..7bf5ade195b 100644
--- a/src/main/persistence/applying-settings/settings-update.ts
+++ b/src/main/persistence/applying-settings/settings-update.ts
@@ -39,7 +39,7 @@ import {
   normalizeSourceControlAiSettings,
   projectSourceControlAiToLegacyCommitMessageAi
 } from '../../../shared/source-control-ai'
-import type { ProtectedSecretPersistence } from '../../protected-secret-persistence'
+import type { ProtectedSecretPersistence } from '../../credentials/protected-secret-persistence'
 import { normalizeNotificationSettings } from './onboarding-normalization'
 import { retireLegacyInstructionsForClearedTextActionRecipes } from './source-control-settings'
 import {
diff --git a/src/main/persistence/applying-settings/terminal-settings-migrations.ts b/src/main/persistence/applying-settings/terminal-settings-migrations.ts
index bccce6f16ca..d593fe3457b 100644
--- a/src/main/persistence/applying-settings/terminal-settings-migrations.ts
+++ b/src/main/persistence/applying-settings/terminal-settings-migrations.ts
@@ -11,7 +11,7 @@ import {
   normalizeTuiAgentArgsRecord,
   normalizeTuiAgentEnvRecord
 } from '../../../shared/tui-agent-launch-defaults'
-import { expandLeadingHomePath } from '../../home-path-expansion'
+import { expandLeadingHomePath } from '../../filesystem/home-path-expansion'
 
 /** Unexpanded, a leading ~ resolves inside each repo and worktrees land in <repo>/~ (#34944). */
 export function expandWorkspaceDirHome(settings: Partial<GlobalSettings>): Partial<GlobalSettings> {
diff --git a/src/main/persistence/applying-settings/ui-state-update.ts b/src/main/persistence/applying-settings/ui-state-update.ts
index 66966709b31..afa237db29f 100644
--- a/src/main/persistence/applying-settings/ui-state-update.ts
+++ b/src/main/persistence/applying-settings/ui-state-update.ts
@@ -30,7 +30,7 @@ import { persistedUIValuesEqual } from '../../../shared/persisted-ui-equality'
 import {
   PROTECTED_SECRET_SLOT,
   type ProtectedSecretPersistence
-} from '../../protected-secret-persistence'
+} from '../../credentials/protected-secret-persistence'
 import {
   normalizeGroupBy,
   normalizeProjectOrderBy,
diff --git a/src/main/persistence/atomic-snapshot-writer.ts b/src/main/persistence/atomic-snapshot-writer.ts
index 5e811f8d544..36084da2578 100644
--- a/src/main/persistence/atomic-snapshot-writer.ts
+++ b/src/main/persistence/atomic-snapshot-writer.ts
@@ -1,7 +1,10 @@
 import { chmodSync, mkdirSync, renameSync, unlinkSync, writeFileSync } from 'node:fs'
 import { chmod, mkdir, rename, rm, writeFile } from 'node:fs/promises'
 import { dirname } from 'node:path'
-import { durableWriteTempPath, removeStaleDurableWriteTempFiles } from '../durable-file-write'
+import {
+  durableWriteTempPath,
+  removeStaleDurableWriteTempFiles
+} from '../filesystem/durable-file-write'
 
 const STALE_WRITE_TEMP_AGE_MS = 24 * 60 * 60 * 1000
 
diff --git a/src/main/persistence/leasing-ssh-ptys/ssh-target-reassignment.ts b/src/main/persistence/leasing-ssh-ptys/ssh-target-reassignment.ts
index 3558ed0aba9..94a2e84936a 100644
--- a/src/main/persistence/leasing-ssh-ptys/ssh-target-reassignment.ts
+++ b/src/main/persistence/leasing-ssh-ptys/ssh-target-reassignment.ts
@@ -6,8 +6,8 @@ import {
   migrateUiHostScopeSshTargetId,
   migrateWorkspaceSessionSshTargetId
 } from '../../ssh/targets/ssh-target-id-migration'
-import type { ProtectedSecretPersistence } from '../../protected-secret-persistence'
-import { sshPtyOwnerLeaseSecretSlot } from '../../protected-secret-persistence'
+import type { ProtectedSecretPersistence } from '../../credentials/protected-secret-persistence'
+import { sshPtyOwnerLeaseSecretSlot } from '../../credentials/protected-secret-persistence'
 import {
   migrateRetirementNamespaceHostIdentity,
   sshHostIdentity
diff --git a/src/main/persistence/leasing-ssh-ptys/ssh-target-state.ts b/src/main/persistence/leasing-ssh-ptys/ssh-target-state.ts
index 9d97a86330a..f7a21997dcd 100644
--- a/src/main/persistence/leasing-ssh-ptys/ssh-target-state.ts
+++ b/src/main/persistence/leasing-ssh-ptys/ssh-target-state.ts
@@ -1,7 +1,7 @@
 import type { PersistedState } from '../../../shared/persisted-state-types'
 import type { RemovedSshTargetTombstone, SshTarget } from '../../../shared/ssh-types'
-import type { ProtectedSecretPersistence } from '../../protected-secret-persistence'
-import { sshPtyOwnerLeaseSecretSlot } from '../../protected-secret-persistence'
+import type { ProtectedSecretPersistence } from '../../credentials/protected-secret-persistence'
+import { sshPtyOwnerLeaseSecretSlot } from '../../credentials/protected-secret-persistence'
 import {
   MAX_REMOVED_SSH_TARGET_TOMBSTONES,
   capRemovedSshTargetTombstones,
diff --git a/src/main/persistence/loading-store/legacy-opencode-go-api-key-migration.test.ts b/src/main/persistence/loading-store/legacy-opencode-go-api-key-migration.test.ts
index 019330f25a1..f94c8a85821 100644
--- a/src/main/persistence/loading-store/legacy-opencode-go-api-key-migration.test.ts
+++ b/src/main/persistence/loading-store/legacy-opencode-go-api-key-migration.test.ts
@@ -8,7 +8,8 @@ const secretStore = vi.hoisted(() => ({
 
 vi.mock('../../../shared/secret-store', () => ({ getSecretStore: () => secretStore }))
 
-const { ProtectedSecretPersistence } = await import('../../protected-secret-persistence')
+const { ProtectedSecretPersistence } =
+  await import('../../credentials/protected-secret-persistence')
 const {
   LEGACY_OPENCODE_GO_API_KEY_SLOT,
   migrateLegacyOpenCodeGoApiKey,
diff --git a/src/main/persistence/loading-store/legacy-opencode-go-api-key-migration.ts b/src/main/persistence/loading-store/legacy-opencode-go-api-key-migration.ts
index aae3491bc7c..6fedf5601e9 100644
--- a/src/main/persistence/loading-store/legacy-opencode-go-api-key-migration.ts
+++ b/src/main/persistence/loading-store/legacy-opencode-go-api-key-migration.ts
@@ -1,4 +1,4 @@
-import type { ProtectedSecretPersistence } from '../../protected-secret-persistence'
+import type { ProtectedSecretPersistence } from '../../credentials/protected-secret-persistence'
 
 // Only migration reads the former encrypted settings slot.
 export const LEGACY_OPENCODE_GO_API_KEY_SLOT = 'settings.opencodeGoApiKey'
diff --git a/src/main/persistence/loading-store/loaded-state-parsing.ts b/src/main/persistence/loading-store/loaded-state-parsing.ts
index 6b8dc2ebc1d..cf8eb39ae81 100644
--- a/src/main/persistence/loading-store/loaded-state-parsing.ts
+++ b/src/main/persistence/loading-store/loaded-state-parsing.ts
@@ -13,7 +13,7 @@ import { logStartupMilestone } from '../../startup/startup-diagnostics'
 import {
   PROTECTED_SECRET_SLOT,
   sshPtyOwnerLeaseSecretSlot
-} from '../../protected-secret-persistence'
+} from '../../credentials/protected-secret-persistence'
 import {
   isLegacyOpenCodeSessionCookie,
   isLegacySshPtyOwnerLease
diff --git a/src/main/persistence/loading-store/profile-state-selective-serialization.test.ts b/src/main/persistence/loading-store/profile-state-selective-serialization.test.ts
index 3ddb82eaa94..309dc1fe115 100644
--- a/src/main/persistence/loading-store/profile-state-selective-serialization.test.ts
+++ b/src/main/persistence/loading-store/profile-state-selective-serialization.test.ts
@@ -1,6 +1,6 @@
 import { afterEach, describe, expect, it, vi } from 'vitest'
 import { getDefaultPersistedState } from '../../../shared/constants'
-import { ProtectedSecretPersistence } from '../../protected-secret-persistence'
+import { ProtectedSecretPersistence } from '../../credentials/protected-secret-persistence'
 import { serializeSelectiveProfileStateDomains } from './profile-state-authority-writes'
 import { StateSerializationSecretHandlingOperations } from './state-serialization-secret-handling'
 
diff --git a/src/main/persistence/loading-store/profile-state-selective-write.ts b/src/main/persistence/loading-store/profile-state-selective-write.ts
index 286626c33c2..08468ff2f89 100644
--- a/src/main/persistence/loading-store/profile-state-selective-write.ts
+++ b/src/main/persistence/loading-store/profile-state-selective-write.ts
@@ -1,4 +1,4 @@
-import type { ProtectedSecretRetentionUpdate } from '../../protected-secret-persistence'
+import type { ProtectedSecretRetentionUpdate } from '../../credentials/protected-secret-persistence'
 import type {
   ProfileStateAuthority,
   ProfileStateDomainReplacement,
diff --git a/src/main/persistence/loading-store/profile-state-temp-cleanup-lifetime.test.ts b/src/main/persistence/loading-store/profile-state-temp-cleanup-lifetime.test.ts
index 006d64efa39..343cc541992 100644
--- a/src/main/persistence/loading-store/profile-state-temp-cleanup-lifetime.test.ts
+++ b/src/main/persistence/loading-store/profile-state-temp-cleanup-lifetime.test.ts
@@ -3,7 +3,7 @@ import { tmpdir } from 'node:os'
 import { basename, join } from 'node:path'
 import { afterEach, expect, it, vi } from 'vitest'
 import { removeTreeSync } from '../../../shared/windows-transient-lock-removal'
-import * as durableFileWrite from '../../durable-file-write'
+import * as durableFileWrite from '../../filesystem/durable-file-write'
 import { STALE_DURABLE_WRITE_TEMP_AGE_MS } from '../tracking-repos/worktree-metadata-normalization'
 import {
   createWorkerMaintenanceFixture,
diff --git a/src/main/persistence/loading-store/state-serialization-secret-handling.ts b/src/main/persistence/loading-store/state-serialization-secret-handling.ts
index dbb19cc6228..2ad4a087e17 100644
--- a/src/main/persistence/loading-store/state-serialization-secret-handling.ts
+++ b/src/main/persistence/loading-store/state-serialization-secret-handling.ts
@@ -10,7 +10,7 @@ import {
   PROTECTED_SECRET_SLOT,
   sshPtyOwnerLeaseSecretSlot,
   type ProtectedSecretRetentionUpdate
-} from '../../protected-secret-persistence'
+} from '../../credentials/protected-secret-persistence'
 import { stripRetiredGlobalSettings } from '../applying-settings/terminal-settings-migrations'
 import { LEGACY_OPENCODE_GO_API_KEY_SLOT } from './legacy-opencode-go-api-key-migration'
 import { omitDefaultWorktreeMetaFieldsInMap } from '../../../shared/worktree/meta-persisted-defaults'
diff --git a/src/main/persistence/loading-store/store-runtime-state.ts b/src/main/persistence/loading-store/store-runtime-state.ts
index 771ec32455f..9f59b7edc35 100644
--- a/src/main/persistence/loading-store/store-runtime-state.ts
+++ b/src/main/persistence/loading-store/store-runtime-state.ts
@@ -1,4 +1,4 @@
-import { removeStaleDurableWriteTempFiles } from '../../durable-file-write'
+import { removeStaleDurableWriteTempFiles } from '../../filesystem/durable-file-write'
 import type { GlobalSettings } from '../../../shared/global-settings-types'
 import type { PersistedState } from '../../../shared/persisted-state-types'
 import type {
@@ -13,7 +13,7 @@ import {
   getProfileTerminalScrollbackSnapshotRoot,
   type TerminalScrollbackSnapshotStorage
 } from '../../terminal-scrollback-snapshots'
-import { ProtectedSecretPersistence } from '../../protected-secret-persistence'
+import { ProtectedSecretPersistence } from '../../credentials/protected-secret-persistence'
 import { getDataFile, getGithubCacheFile } from './user-data-path'
 import { dirname, join } from 'node:path'
 import { STALE_DURABLE_WRITE_TEMP_AGE_MS } from '../tracking-repos/worktree-metadata-normalization'
diff --git a/src/main/persistence/loading-store/write-flush-barriers.ts b/src/main/persistence/loading-store/write-flush-barriers.ts
index 666fd759fa8..bb302fcdadb 100644
--- a/src/main/persistence/loading-store/write-flush-barriers.ts
+++ b/src/main/persistence/loading-store/write-flush-barriers.ts
@@ -1,6 +1,6 @@
 import { writeFileSync, renameSync, unlinkSync } from 'node:fs'
 import { rename, rm, writeFile } from 'node:fs/promises'
-import { durableWriteTempPath } from '../../durable-file-write'
+import { durableWriteTempPath } from '../../filesystem/durable-file-write'
 import { getGithubCacheFile } from './user-data-path'
 
 import type { StoreRuntimeState } from './store-runtime-state'
diff --git a/src/main/persistence/migrating-orcad-catalog/migration-journal-directory.ts b/src/main/persistence/migrating-orcad-catalog/migration-journal-directory.ts
index 9fe407afb51..4743ef1c27e 100644
--- a/src/main/persistence/migrating-orcad-catalog/migration-journal-directory.ts
+++ b/src/main/persistence/migrating-orcad-catalog/migration-journal-directory.ts
@@ -4,7 +4,7 @@ import { join } from 'node:path'
 import { writeSecureJsonFileWithinLimit } from '../../../shared/bounded-secure-json-file'
 import { errorMessage } from '../../../shared/error-message'
 import { readNodeFileSyncWithinLimit } from '../../../shared/node-bounded-file-reader'
-import { syncDirectoryDurablySync } from '../../durable-file-write'
+import { syncDirectoryDurablySync } from '../../filesystem/durable-file-write'
 
 const JOURNAL_FILE = /^[A-Za-z0-9_-]{1,128}\.json$/
 // `<id>.json.<pid>.<ms>.<rand>.tmp`: a durable write that died before its rename.
diff --git a/src/main/persistence/migrating-orcad-catalog/orcad-migration-blob-installers.ts b/src/main/persistence/migrating-orcad-catalog/orcad-migration-blob-installers.ts
index d8a082a0698..ebc946141cf 100644
--- a/src/main/persistence/migrating-orcad-catalog/orcad-migration-blob-installers.ts
+++ b/src/main/persistence/migrating-orcad-catalog/orcad-migration-blob-installers.ts
@@ -9,7 +9,7 @@ import {
   parseOrcadMigrationTerminalRestoreHintsText,
   type OrcadMigrationTerminalRestoreHint
 } from '../../../shared/orcad-migration/orcad-migration-terminal-restore-hints'
-import { syncDirectoryDurablySync } from '../../durable-file-write'
+import { syncDirectoryDurablySync } from '../../filesystem/durable-file-write'
 import {
   getOrcadMigrationReceivedBlobPath,
   stagedOrcadMigrationBlobFiles
diff --git a/src/main/persistence/migrating-orcad-catalog/orcad-migration-blob-staging.ts b/src/main/persistence/migrating-orcad-catalog/orcad-migration-blob-staging.ts
index 4c87a19cc8e..7f21144ce8c 100644
--- a/src/main/persistence/migrating-orcad-catalog/orcad-migration-blob-staging.ts
+++ b/src/main/persistence/migrating-orcad-catalog/orcad-migration-blob-staging.ts
@@ -15,7 +15,7 @@ import {
   type OrcadMigrationBlobUploadState
 } from '../../../shared/orcad-migration/orcad-migration-blob-transfer'
 import type { OrcadMigrationManifest } from '../../../shared/orcad-migration/orcad-migration-manifest'
-import { syncDirectoryDurablySync } from '../../durable-file-write'
+import { syncDirectoryDurablySync } from '../../filesystem/durable-file-write'
 import {
   appendOrcadMigrationStagedChunk,
   ensureOrcadMigrationDirectory,
diff --git a/src/main/persistence/migrating-orcad-catalog/orcad-migration-staged-file.ts b/src/main/persistence/migrating-orcad-catalog/orcad-migration-staged-file.ts
index 951b35ecb2f..5b1370e5468 100644
--- a/src/main/persistence/migrating-orcad-catalog/orcad-migration-staged-file.ts
+++ b/src/main/persistence/migrating-orcad-catalog/orcad-migration-staged-file.ts
@@ -16,7 +16,7 @@ import {
 } from 'node:fs'
 import { join } from 'node:path'
 import type { OrcadMigrationManifest } from '../../../shared/orcad-migration/orcad-migration-manifest'
-import { syncDirectoryDurablySync } from '../../durable-file-write'
+import { syncDirectoryDurablySync } from '../../filesystem/durable-file-write'
 
 export const ORCAD_MIGRATION_STAGING_DIRECTORY = '.orcad-migration-staging'
 
diff --git a/src/main/persistence/migrating-orcad-catalog/orcad-scrollback-snapshot-transfer.ts b/src/main/persistence/migrating-orcad-catalog/orcad-scrollback-snapshot-transfer.ts
index c02720a0142..3b7a1fdbdd0 100644
--- a/src/main/persistence/migrating-orcad-catalog/orcad-scrollback-snapshot-transfer.ts
+++ b/src/main/persistence/migrating-orcad-catalog/orcad-scrollback-snapshot-transfer.ts
@@ -8,7 +8,7 @@ import {
   type OrcadMigrationSnapshotUploadState,
   type OrcadMigrationTerminalScrollbackSnapshot
 } from '../../../shared/orcad-migration/orcad-migration-scrollback'
-import { syncDirectoryDurablySync } from '../../durable-file-write'
+import { syncDirectoryDurablySync } from '../../filesystem/durable-file-write'
 import {
   getTerminalScrollbackSnapshotPath,
   getTerminalScrollbackSnapshotRoot,
diff --git a/src/main/persistence/migrating-orcad-catalog/orcad-shell-history-installer.ts b/src/main/persistence/migrating-orcad-catalog/orcad-shell-history-installer.ts
index 8876a7c59de..7125f723818 100644
--- a/src/main/persistence/migrating-orcad-catalog/orcad-shell-history-installer.ts
+++ b/src/main/persistence/migrating-orcad-catalog/orcad-shell-history-installer.ts
@@ -22,7 +22,7 @@ import {
   durableWriteTempPath,
   syncDirectoryDurablySync,
   writeFileDurableSync
-} from '../../durable-file-write'
+} from '../../filesystem/durable-file-write'
 import { resolveUnixPaneShellPath } from '../../daemon/shell-ready'
 import { resolveUnixShellPath } from '../../providers/local-pty/local-pty-executable-spawn'
 import { readHistoryMeta, resolveShellKind } from '../../terminal-history'
diff --git a/src/main/persistence/migrating-orcad-catalog/orcad-terminal-history-installer.ts b/src/main/persistence/migrating-orcad-catalog/orcad-terminal-history-installer.ts
index f82a95b76d4..ca9e1b2e9a2 100644
--- a/src/main/persistence/migrating-orcad-catalog/orcad-terminal-history-installer.ts
+++ b/src/main/persistence/migrating-orcad-catalog/orcad-terminal-history-installer.ts
@@ -17,7 +17,7 @@ import { parsePaneKey } from '../../../shared/stable-pane-id'
 import { getHistorySessionDirName } from '../../daemon/history-paths'
 import { isTerminalCheckpointFile } from '../../daemon/terminal-history-checkpoint-reader'
 import type { SessionMeta } from '../../daemon/terminal-history-metadata'
-import { syncDirectoryDurablySync } from '../../durable-file-write'
+import { syncDirectoryDurablySync } from '../../filesystem/durable-file-write'
 import {
   getOrcadMigrationReceivedBlobPath,
   listOrcadMigrationReceivedBlobNames
diff --git a/src/main/persistence/migrating-orcad-catalog/orcad-terminal-restore-hint-store.ts b/src/main/persistence/migrating-orcad-catalog/orcad-terminal-restore-hint-store.ts
index fb90abd2816..16b821009c4 100644
--- a/src/main/persistence/migrating-orcad-catalog/orcad-terminal-restore-hint-store.ts
+++ b/src/main/persistence/migrating-orcad-catalog/orcad-terminal-restore-hint-store.ts
@@ -2,7 +2,7 @@
 import { readFileSync } from 'node:fs'
 import { join } from 'node:path'
 import { z } from 'zod'
-import { durableWriteTempPath, writeFileDurableSync } from '../../durable-file-write'
+import { durableWriteTempPath, writeFileDurableSync } from '../../filesystem/durable-file-write'
 import {
   MAX_ORCAD_MIGRATION_TERMINAL_RESTORE_HINTS,
   isOrcadMigrationTerminalRestoreHintCwd,
diff --git a/src/main/persistence/profile-state/legacy-json/profile-state-authority-exports.ts b/src/main/persistence/profile-state/legacy-json/profile-state-authority-exports.ts
index a549ceaaa6f..13ff30a6109 100644
--- a/src/main/persistence/profile-state/legacy-json/profile-state-authority-exports.ts
+++ b/src/main/persistence/profile-state/legacy-json/profile-state-authority-exports.ts
@@ -1,6 +1,6 @@
 import { existsSync, mkdirSync, readFileSync } from 'node:fs'
 import { dirname } from 'node:path'
-import { durableWriteTempPath, writeFileDurableSync } from '../../../durable-file-write'
+import { durableWriteTempPath, writeFileDurableSync } from '../../../filesystem/durable-file-write'
 import { readProfileStateSnapshot } from '../profile-state-documents'
 import {
   stageProfileStateRecoveryJson,
diff --git a/src/main/persistence/profile-state/legacy-json/profile-state-recovery.ts b/src/main/persistence/profile-state/legacy-json/profile-state-recovery.ts
index bd05ad21150..d913fedf5c3 100644
--- a/src/main/persistence/profile-state/legacy-json/profile-state-recovery.ts
+++ b/src/main/persistence/profile-state/legacy-json/profile-state-recovery.ts
@@ -2,7 +2,7 @@ import { profileStateDatabaseFiles } from '../profile-state-storage-classificati
 import { existsSync, mkdirSync, readFileSync, rmSync } from 'node:fs'
 import { dirname } from 'node:path'
 import { parseProfileStateRoot } from '../profile-state-document-validation'
-import { durableWriteTempPath, writeFileDurableSync } from '../../../durable-file-write'
+import { durableWriteTempPath, writeFileDurableSync } from '../../../filesystem/durable-file-write'
 import { bestEffortFsyncDirectorySync } from '../../../../shared/secure-file'
 import {
   quarantineProfileStateDatabase,
diff --git a/src/main/persistence/profile-state/legacy-json/profile-state-versioned-export.test.ts b/src/main/persistence/profile-state/legacy-json/profile-state-versioned-export.test.ts
index edf3050c976..26e2d53d453 100644
--- a/src/main/persistence/profile-state/legacy-json/profile-state-versioned-export.test.ts
+++ b/src/main/persistence/profile-state/legacy-json/profile-state-versioned-export.test.ts
@@ -2,7 +2,7 @@ import * as fs from 'node:fs'
 import { tmpdir } from 'node:os'
 import { basename, join } from 'node:path'
 import { afterEach, describe, expect, it, vi } from 'vitest'
-import { durableWriteTempPath, writeFileDurableSync } from '../../../durable-file-write'
+import { durableWriteTempPath, writeFileDurableSync } from '../../../filesystem/durable-file-write'
 import { profileStateJsonExportPath } from './profile-state-export-path'
 import { writeVersionedProfileStateExport } from './profile-state-versioned-export'
 
diff --git a/src/main/persistence/profile-state/legacy-json/profile-state-versioned-export.ts b/src/main/persistence/profile-state/legacy-json/profile-state-versioned-export.ts
index 674db03ce96..9aa5f051cbc 100644
--- a/src/main/persistence/profile-state/legacy-json/profile-state-versioned-export.ts
+++ b/src/main/persistence/profile-state/legacy-json/profile-state-versioned-export.ts
@@ -1,7 +1,10 @@
 import { lstatSync, mkdirSync, readFileSync, rmSync } from 'node:fs'
 import { dirname } from 'node:path'
 import { bestEffortFsyncDirectorySync, fsyncFileSync } from '../../../../shared/secure-file'
-import { durableWriteTempPath, publishFileDurableSync } from '../../../durable-file-write'
+import {
+  durableWriteTempPath,
+  publishFileDurableSync
+} from '../../../filesystem/durable-file-write'
 import {
   profileStateJsonExportPath,
   profileStateJsonExportPaths
diff --git a/src/main/persistence/profile-state/profile-state-authority-marker-writes.test.ts b/src/main/persistence/profile-state/profile-state-authority-marker-writes.test.ts
index cd1ddc0cfb2..130e3800ab5 100644
--- a/src/main/persistence/profile-state/profile-state-authority-marker-writes.test.ts
+++ b/src/main/persistence/profile-state/profile-state-authority-marker-writes.test.ts
@@ -2,7 +2,7 @@ import { existsSync, mkdirSync, mkdtempSync, readFileSync, rmSync, writeFileSync
 import { tmpdir } from 'node:os'
 import { join } from 'node:path'
 import { afterEach, describe, expect, it, vi } from 'vitest'
-import * as durableFileWrite from '../../durable-file-write'
+import * as durableFileWrite from '../../filesystem/durable-file-write'
 import { prepareProfileProjectDomainChanges } from '../../orca-profiles/profile-project-domain-changes'
 import {
   readProfileProjectTransferState,
diff --git a/src/main/persistence/profile-state/profile-state-authority-marker.test.ts b/src/main/persistence/profile-state/profile-state-authority-marker.test.ts
index 33a84c71c25..95a44786008 100644
--- a/src/main/persistence/profile-state/profile-state-authority-marker.test.ts
+++ b/src/main/persistence/profile-state/profile-state-authority-marker.test.ts
@@ -2,7 +2,7 @@ import * as fs from 'node:fs'
 import { tmpdir } from 'node:os'
 import { join } from 'node:path'
 import { afterEach, describe, expect, it, vi } from 'vitest'
-import * as durableFileWrite from '../../durable-file-write'
+import * as durableFileWrite from '../../filesystem/durable-file-write'
 import { bootstrapProfileStateAuthority } from './profile-state-authority-bootstrap'
 import {
   hasProfileStateAuthorityMarker,
diff --git a/src/main/persistence/profile-state/profile-state-authority-marker.ts b/src/main/persistence/profile-state/profile-state-authority-marker.ts
index 20dff8282ad..baf3536aaa2 100644
--- a/src/main/persistence/profile-state/profile-state-authority-marker.ts
+++ b/src/main/persistence/profile-state/profile-state-authority-marker.ts
@@ -1,5 +1,5 @@
 import { lstatSync } from 'node:fs'
-import { durableWriteTempPath, writeFileDurableSync } from '../../durable-file-write'
+import { durableWriteTempPath, writeFileDurableSync } from '../../filesystem/durable-file-write'
 
 export function profileStateAuthorityMarkerPath(databaseFile: string): string {
   return `${databaseFile}.authority`
diff --git a/src/main/persistence/profile-state/profile-state-backup-temporary-files.ts b/src/main/persistence/profile-state/profile-state-backup-temporary-files.ts
index 3e22f9f80f8..1aa593df9ab 100644
--- a/src/main/persistence/profile-state/profile-state-backup-temporary-files.ts
+++ b/src/main/persistence/profile-state/profile-state-backup-temporary-files.ts
@@ -1,6 +1,6 @@
 import { createHash } from 'node:crypto'
 import { lstat, readdir, rm } from 'node:fs/promises'
-import { durableWriteTempPath } from '../../durable-file-write'
+import { durableWriteTempPath } from '../../filesystem/durable-file-write'
 import { profileStateAccessBootIdentity } from './profile-state-access-identity'
 import { profileStateAccessPidNamespace } from './profile-state-access-owner'
 import { basename, dirname, join } from 'node:path'
diff --git a/src/main/persistence/profile-state/profile-state-backup-worker.ts b/src/main/persistence/profile-state/profile-state-backup-worker.ts
index adf62b801e6..6f4d02155d7 100644
--- a/src/main/persistence/profile-state/profile-state-backup-worker.ts
+++ b/src/main/persistence/profile-state/profile-state-backup-worker.ts
@@ -7,7 +7,7 @@ import { Worker } from 'node:worker_threads'
 import {
   currentWorkerEntryLayout,
   resolveWorkerThreadEntryPath
-} from '../../worker-thread-entry-path'
+} from '../../worker-threads/worker-thread-entry-path'
 import { type ProfileStateBackupJob, writeProfileStateBackup } from './profile-state-backup-job'
 import { isRecord } from './profile-state-document-validation'
 
diff --git a/src/main/persistence/profile-state/profile-state-database-publication.ts b/src/main/persistence/profile-state/profile-state-database-publication.ts
index d58ea038cd9..f4c5e9d4b18 100644
--- a/src/main/persistence/profile-state/profile-state-database-publication.ts
+++ b/src/main/persistence/profile-state/profile-state-database-publication.ts
@@ -1,5 +1,5 @@
 import { dirname } from 'node:path'
-import { publishFileDurableSync } from '../../durable-file-write'
+import { publishFileDurableSync } from '../../filesystem/durable-file-write'
 import { profileStatePublicationFailureText } from './profile-state-startup-failure'
 
 class ProfileStateDatabasePublicationError extends Error {
diff --git a/src/main/persistence/profile-state/profile-state-database-quarantine.ts b/src/main/persistence/profile-state/profile-state-database-quarantine.ts
index c8023c4fc17..985cb4e9114 100644
--- a/src/main/persistence/profile-state/profile-state-database-quarantine.ts
+++ b/src/main/persistence/profile-state/profile-state-database-quarantine.ts
@@ -3,7 +3,7 @@ import { randomUUID } from 'node:crypto'
 import { existsSync, mkdirSync, rmSync } from 'node:fs'
 import { basename, dirname, join } from 'node:path'
 import { bestEffortFsyncDirectorySync, fsyncFileSync } from '../../../shared/secure-file'
-import { durableWriteTempPath, writeFileDurableSync } from '../../durable-file-write'
+import { durableWriteTempPath, writeFileDurableSync } from '../../filesystem/durable-file-write'
 import { hardenSqliteDatabaseFiles } from '../../sqlite/harden-database-files'
 import { copyProfileStateRecoveryFiles } from './profile-state-recovery-copy'
 
diff --git a/src/main/persistence/profile-state/profile-state-database-recovery.test.ts b/src/main/persistence/profile-state/profile-state-database-recovery.test.ts
index ebfca9cccfe..544be9161a5 100644
--- a/src/main/persistence/profile-state/profile-state-database-recovery.test.ts
+++ b/src/main/persistence/profile-state/profile-state-database-recovery.test.ts
@@ -12,7 +12,7 @@ import { tmpdir } from 'node:os'
 import { basename, dirname, join } from 'node:path'
 import { afterEach, describe, expect, it, vi } from 'vitest'
 import Database from '../../sqlite/sync-database'
-import * as durableFileWrite from '../../durable-file-write'
+import * as durableFileWrite from '../../filesystem/durable-file-write'
 import {
   openProfileStateDatabase,
   openProfileStateDatabaseReadOnly
diff --git a/src/main/persistence/profile-state/profile-state-database-recovery.ts b/src/main/persistence/profile-state/profile-state-database-recovery.ts
index c44f0f83e51..9a5ec67b392 100644
--- a/src/main/persistence/profile-state/profile-state-database-recovery.ts
+++ b/src/main/persistence/profile-state/profile-state-database-recovery.ts
@@ -1,7 +1,7 @@
 import { profileStateDatabaseFiles } from './profile-state-storage-classification'
 import { existsSync, lstatSync, mkdirSync, rmSync } from 'node:fs'
 import { dirname } from 'node:path'
-import { durableWriteTempPath, renameDurableSync } from '../../durable-file-write'
+import { durableWriteTempPath, renameDurableSync } from '../../filesystem/durable-file-write'
 import { hardenSqliteDatabaseFiles } from '../../sqlite/harden-database-files'
 import { bestEffortFsyncDirectorySync, fsyncFileSync } from '../../../shared/secure-file'
 import { openProfileStateDatabaseReadOnly } from './profile-state-database'
diff --git a/src/main/persistence/profile-state/profile-state-database-snapshot.test.ts b/src/main/persistence/profile-state/profile-state-database-snapshot.test.ts
index 238e067e9a3..236cf80f215 100644
--- a/src/main/persistence/profile-state/profile-state-database-snapshot.test.ts
+++ b/src/main/persistence/profile-state/profile-state-database-snapshot.test.ts
@@ -19,7 +19,7 @@ import {
 import { exportProfileStateJson, importProfileStateJson } from './profile-state-documents'
 import { writeProfileStateDatabaseSnapshotAsync } from './profile-state-database-snapshot'
 import type Database from '../../sqlite/sync-database'
-import * as durableFileWrite from '../../durable-file-write'
+import * as durableFileWrite from '../../filesystem/durable-file-write'
 import * as fsPromises from 'node:fs/promises'
 
 vi.mock('node:fs/promises', async (importOriginal) => {
diff --git a/src/main/persistence/profile-state/profile-state-database-snapshot.ts b/src/main/persistence/profile-state/profile-state-database-snapshot.ts
index 903c2a6644a..fd216434819 100644
--- a/src/main/persistence/profile-state/profile-state-database-snapshot.ts
+++ b/src/main/persistence/profile-state/profile-state-database-snapshot.ts
@@ -3,7 +3,7 @@ import { access, mkdir, open, realpath, rm, stat } from 'node:fs/promises'
 import { basename, dirname, resolve } from 'node:path'
 import Database from '../../sqlite/sync-database'
 import { hardenSqliteDatabaseFiles } from '../../sqlite/harden-database-files'
-import { durableWriteTempPath, renameDurable } from '../../durable-file-write'
+import { durableWriteTempPath, renameDurable } from '../../filesystem/durable-file-write'
 
 /** Caller owns the destination and keeps the source connection open until completion. */
 export async function writeProfileStateDatabaseSnapshotAsync(
diff --git a/src/main/persistence/profile-state/profile-state-recovery-command.ts b/src/main/persistence/profile-state/profile-state-recovery-command.ts
index 214b456ec6f..1912ff7ddc4 100644
--- a/src/main/persistence/profile-state/profile-state-recovery-command.ts
+++ b/src/main/persistence/profile-state/profile-state-recovery-command.ts
@@ -15,7 +15,7 @@ import { restoreProfileStateJsonExport } from './legacy-json/profile-state-recov
 import { restoreProfileStateDatabaseBackup } from './profile-state-database-recovery'
 import { quarantineProfileStateDatabase } from './profile-state-database-quarantine'
 import { ProfileStateSqliteAuthority } from './profile-state-sqlite-authority'
-import { durableWriteTempPath, writeFileDurableSync } from '../../durable-file-write'
+import { durableWriteTempPath, writeFileDurableSync } from '../../filesystem/durable-file-write'
 import { assertProfileStateMaintenance, type ProfileStateMaintenance } from './profile-state-access'
 import {
   openProfileStateDatabaseReadOnly,
diff --git a/src/main/persistence/profile-state/profile-state-startup-authority.test.ts b/src/main/persistence/profile-state/profile-state-startup-authority.test.ts
index 615c15b40e5..efe8684a611 100644
--- a/src/main/persistence/profile-state/profile-state-startup-authority.test.ts
+++ b/src/main/persistence/profile-state/profile-state-startup-authority.test.ts
@@ -1,5 +1,5 @@
 import { build } from 'esbuild'
-import type * as WorkerEntryPath from '../../worker-thread-entry-path'
+import type * as WorkerEntryPath from '../../worker-threads/worker-thread-entry-path'
 import { afterAll, afterEach, beforeAll, describe, expect, it, vi } from 'vitest'
 import { existsSync, mkdtempSync, readFileSync, rmSync, writeFileSync } from 'node:fs'
 import { tmpdir } from 'node:os'
@@ -13,7 +13,7 @@ import {
 import { openProfileStateDatabase, profileStateDatabaseFile } from './profile-state-database'
 
 const bundle = vi.hoisted(() => ({ directory: '' }))
-vi.mock('../../worker-thread-entry-path', async (importOriginal) => {
+vi.mock('../../worker-threads/worker-thread-entry-path', async (importOriginal) => {
   const original = await importOriginal<typeof WorkerEntryPath>()
   return {
     ...original,
diff --git a/src/main/persistence/profile-state/profile-state-writer-worker-path.ts b/src/main/persistence/profile-state/profile-state-writer-worker-path.ts
index d1068eb26b0..0f1d5924977 100644
--- a/src/main/persistence/profile-state/profile-state-writer-worker-path.ts
+++ b/src/main/persistence/profile-state/profile-state-writer-worker-path.ts
@@ -3,7 +3,7 @@ import { dirname, join } from 'node:path'
 import {
   currentWorkerEntryLayout,
   resolveWorkerThreadEntryPath
-} from '../../worker-thread-entry-path'
+} from '../../worker-threads/worker-thread-entry-path'
 
 export function resolveProfileStateWriterWorkerPath(moduleDir = __dirname): string {
   const entry = resolveWorkerThreadEntryPath(
diff --git a/src/main/persistence/restoring-sessions/floating-workspace-normalization.ts b/src/main/persistence/restoring-sessions/floating-workspace-normalization.ts
index d83e5306cc7..25c4c98086f 100644
--- a/src/main/persistence/restoring-sessions/floating-workspace-normalization.ts
+++ b/src/main/persistence/restoring-sessions/floating-workspace-normalization.ts
@@ -1,6 +1,6 @@
 import { realpathSync, statSync } from 'node:fs'
 import { isAbsolute, resolve } from 'node:path'
-import { expandLeadingHomePath } from '../../home-path-expansion'
+import { expandLeadingHomePath } from '../../filesystem/home-path-expansion'
 
 export function resolveFloatingWorkspacePath(input: string, home: string): string {
   const expanded = expandLeadingHomePath(input, home)
diff --git a/src/main/plugins/panels/plugin-source-transpile-client.ts b/src/main/plugins/panels/plugin-source-transpile-client.ts
index 6e6e5e03879..47ff58c995c 100644
--- a/src/main/plugins/panels/plugin-source-transpile-client.ts
+++ b/src/main/plugins/panels/plugin-source-transpile-client.ts
@@ -3,7 +3,7 @@ import { Worker } from 'node:worker_threads'
 import {
   currentWorkerEntryLayout,
   resolveWorkerThreadEntryPath
-} from '../../worker-thread-entry-path'
+} from '../../worker-threads/worker-thread-entry-path'
 import type {
   PluginSourceTranspiled,
   PluginSourceTranspileRequest,
diff --git a/src/main/plugins/view/plugin-view-renderer-relay.ts b/src/main/plugins/view/plugin-view-renderer-relay.ts
index 1bf50fd342c..4d4e016fc6b 100644
--- a/src/main/plugins/view/plugin-view-renderer-relay.ts
+++ b/src/main/plugins/view/plugin-view-renderer-relay.ts
@@ -1,6 +1,6 @@
 import { randomUUID } from 'node:crypto'
 import { ipcMain, type IpcMainEvent, type WebContents } from 'electron'
-import { addFanoutListener, addFanoutListeners } from '../../event-listener-fanout'
+import { addFanoutListener, addFanoutListeners } from '../../runtime/events/event-listener-fanout'
 import {
   PLUGIN_VIEW_REPLY_CHANNEL,
   PLUGIN_VIEW_REQUEST_CHANNEL,
diff --git a/src/main/ports/port-scan-command-client.ts b/src/main/ports/port-scan-command-client.ts
index 25ff9511560..daafdbc944e 100644
--- a/src/main/ports/port-scan-command-client.ts
+++ b/src/main/ports/port-scan-command-client.ts
@@ -1,12 +1,12 @@
 import { existsSync } from 'node:fs'
 import { Worker } from 'node:worker_threads'
-import type { WorkerThreadFactory } from '../lazy-worker-thread-host'
+import type { WorkerThreadFactory } from '../worker-threads/worker-thread-transport'
 import {
   currentWorkerEntryLayout,
   resolveWorkerThreadEntryPath,
   type WorkerEntryLayout
-} from '../worker-thread-entry-path'
-import { WorkerThreadRequestQueue } from '../worker-thread-request-queue'
+} from '../worker-threads/worker-thread-entry-path'
+import { WorkerThreadRequestQueue } from '../worker-threads/worker-thread-request-queue'
 import {
   PORT_SCAN_COMMAND_TIMEOUT_MS,
   PortScanCommandTimeoutError,
diff --git a/src/main/providers/local-filesystem-provider.ts b/src/main/providers/local-filesystem-provider.ts
index c0e2bba4e02..d46dfb6f44b 100644
--- a/src/main/providers/local-filesystem-provider.ts
+++ b/src/main/providers/local-filesystem-provider.ts
@@ -5,7 +5,7 @@ import {
   readAuthorizedDocPreviewFile,
   readAuthorizedDocPreviewFileChunk
 } from '../../shared/doc-preview-file-access'
-import { renameLocalPathSerializedByDestination } from '../destination-serialized-local-rename'
+import { renameLocalPathSerializedByDestination } from '../filesystem/destination-serialized-local-rename'
 import type { resolveAuthorizedPath as ResolveAuthorizedPath } from '../ipc/filesystem/filesystem-auth'
 import { isENOENT } from '../ipc/filesystem/filesystem-path-containment'
 import {
diff --git a/src/main/rate-limits/gemini-oauth-sources.ts b/src/main/rate-limits/gemini-oauth-sources.ts
index 81d5aa43fd6..ce86f5d9259 100644
--- a/src/main/rate-limits/gemini-oauth-sources.ts
+++ b/src/main/rate-limits/gemini-oauth-sources.ts
@@ -3,7 +3,7 @@ import { homedir } from 'node:os'
 import path from 'node:path'
 import { getMainHttpClient } from '../network/http-client'
 import { extractOAuthClientCredentials } from './gemini-cli-oauth-extractor'
-import { writeCredentialFileAtomic } from '../integration-credential-file'
+import { writeCredentialFileAtomic } from '../credentials/integration-credential-file'
 
 const API_TIMEOUT_MS = 10_000
 const OAUTH_CREDS_PATH = path.join(homedir(), '.gemini', 'oauth_creds.json')
diff --git a/src/main/rate-limits/gemini-usage-fetcher.fallback.test.ts b/src/main/rate-limits/gemini-usage-fetcher.fallback.test.ts
index 6ab5077b63b..34d8636c92f 100644
--- a/src/main/rate-limits/gemini-usage-fetcher.fallback.test.ts
+++ b/src/main/rate-limits/gemini-usage-fetcher.fallback.test.ts
@@ -23,7 +23,7 @@ vi.mock('node:fs/promises', () => ({
 }))
 
 // Refresh must never write the developer's real ~/.gemini.
-vi.mock('../integration-credential-file', () => ({
+vi.mock('../credentials/integration-credential-file', () => ({
   writeCredentialFileAtomic: vi.fn().mockReturnValue(true)
 }))
 
diff --git a/src/main/rate-limits/gemini-usage-fetcher.test.ts b/src/main/rate-limits/gemini-usage-fetcher.test.ts
index 609c815dd2d..b072ea4c0de 100644
--- a/src/main/rate-limits/gemini-usage-fetcher.test.ts
+++ b/src/main/rate-limits/gemini-usage-fetcher.test.ts
@@ -18,7 +18,7 @@ vi.mock('node:fs/promises', () => ({
 }))
 
 // Refresh must never write the developer's real ~/.gemini.
-vi.mock('../integration-credential-file', () => ({
+vi.mock('../credentials/integration-credential-file', () => ({
   writeCredentialFileAtomic: vi.fn().mockReturnValue(true)
 }))
 
diff --git a/src/main/runtime/agent-session/records/agent-session-recovery-capsule.test.ts b/src/main/runtime/agent-session/records/agent-session-recovery-capsule.test.ts
index 0db1984c3f3..9310b2e6e34 100644
--- a/src/main/runtime/agent-session/records/agent-session-recovery-capsule.test.ts
+++ b/src/main/runtime/agent-session/records/agent-session-recovery-capsule.test.ts
@@ -3,7 +3,7 @@ import { tmpdir } from 'node:os'
 import { join } from 'node:path'
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
 import { z } from 'zod'
-import * as durable from '../../../durable-file-write'
+import * as durable from '../../../filesystem/durable-file-write'
 import {
   marker,
   NOW,
diff --git a/src/main/runtime/agent-session/records/agent-session-recovery-capsule.ts b/src/main/runtime/agent-session/records/agent-session-recovery-capsule.ts
index 9a29e4f3c7b..ad565f79c77 100644
--- a/src/main/runtime/agent-session/records/agent-session-recovery-capsule.ts
+++ b/src/main/runtime/agent-session/records/agent-session-recovery-capsule.ts
@@ -8,8 +8,8 @@ import {
   removeStaleDurableWriteTempFiles,
   renameDurable,
   writeTempFileDurable
-} from '../../../durable-file-write'
-import { withFileTransactionLock } from '../../../file-transaction-lock'
+} from '../../../filesystem/durable-file-write'
+import { withFileTransactionLock } from '../../../filesystem/file-transaction-lock'
 import {
   MAX_FAILURE_FIELD_LENGTH,
   normalizeState,
diff --git a/src/main/runtime/agent-session/records/agent-session-runtime-end-record.test.ts b/src/main/runtime/agent-session/records/agent-session-runtime-end-record.test.ts
index 9e1d4514746..38b2abdc221 100644
--- a/src/main/runtime/agent-session/records/agent-session-runtime-end-record.test.ts
+++ b/src/main/runtime/agent-session/records/agent-session-runtime-end-record.test.ts
@@ -5,10 +5,10 @@ import { mkdir, mkdtemp, readdir, rm, utimes, writeFile } from 'node:fs/promises
 import { tmpdir } from 'node:os'
 import { join } from 'node:path'
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
-import type * as DurableFileWrite from '../../../durable-file-write'
+import type * as DurableFileWrite from '../../../filesystem/durable-file-write'
 
 const writes = vi.hoisted(() => ({ fail: false }))
-vi.mock('../../../durable-file-write', async (importOriginal) => {
+vi.mock('../../../filesystem/durable-file-write', async (importOriginal) => {
   const actual = await importOriginal<typeof DurableFileWrite>()
   return {
     ...actual,
diff --git a/src/main/runtime/agent-session/records/agent-session-runtime-end-record.ts b/src/main/runtime/agent-session/records/agent-session-runtime-end-record.ts
index 4991950fb9e..f1f993a98fd 100644
--- a/src/main/runtime/agent-session/records/agent-session-runtime-end-record.ts
+++ b/src/main/runtime/agent-session/records/agent-session-runtime-end-record.ts
@@ -3,7 +3,7 @@
 
 import { mkdirSync, readdirSync, rmSync, statSync } from 'node:fs'
 import { join } from 'node:path'
-import { durableWriteTempPath, writeFileDurableSync } from '../../../durable-file-write'
+import { durableWriteTempPath, writeFileDurableSync } from '../../../filesystem/durable-file-write'
 import { readNodeFileSyncWithinLimit } from '../../../../shared/node-bounded-file-reader'
 import type { AgentSessionOrcaStopCause } from '../../../../shared/agent-session/lifecycle/agent-session-orca-stop'
 import {
diff --git a/src/main/in-flight-run-dedupe.ts b/src/main/runtime/concurrency/in-flight-run-dedupe.ts
similarity index 100%
rename from src/main/in-flight-run-dedupe.ts
rename to src/main/runtime/concurrency/in-flight-run-dedupe.ts
diff --git a/src/main/runtime/device-registry.ts b/src/main/runtime/device-registry.ts
index 60b9de61c55..4de5e93e72c 100644
--- a/src/main/runtime/device-registry.ts
+++ b/src/main/runtime/device-registry.ts
@@ -1,7 +1,7 @@
 // Per-device revocable tokens isolate compromises; persist with hardened metadata-style permissions.
 import { join } from 'node:path'
 import type { DeviceScope } from '../../shared/runtime-types'
-import { removeStaleDurableWriteTempFiles } from '../durable-file-write'
+import { removeStaleDurableWriteTempFiles } from '../filesystem/durable-file-write'
 import { DEVICE_REGISTRY_FILENAME } from './mobile-pairing-files'
 import { mintTokenDevice } from './device-credential'
 import { planDeviceKeyFork } from './device-key-fork'
diff --git a/src/main/event-listener-fanout.test.ts b/src/main/runtime/events/event-listener-fanout.test.ts
similarity index 100%
rename from src/main/event-listener-fanout.test.ts
rename to src/main/runtime/events/event-listener-fanout.test.ts
diff --git a/src/main/event-listener-fanout.ts b/src/main/runtime/events/event-listener-fanout.ts
similarity index 100%
rename from src/main/event-listener-fanout.ts
rename to src/main/runtime/events/event-listener-fanout.ts
diff --git a/src/main/runtime/host-descriptor.ts b/src/main/runtime/host-descriptor.ts
index 1105c296153..a38087c82d6 100644
--- a/src/main/runtime/host-descriptor.ts
+++ b/src/main/runtime/host-descriptor.ts
@@ -6,7 +6,7 @@ import {
   type RuntimeHostDescriptor
 } from '../../shared/runtime-host-descriptor'
 import { profileStateAccessMachineIdentity } from '../persistence/profile-state/profile-state-access-identity'
-import { withFileTransactionLock } from '../file-transaction-lock'
+import { withFileTransactionLock } from '../filesystem/file-transaction-lock'
 import type { RuntimeSourceStamp } from '../../shared/runtime-source-env'
 
 export const HOST_INSTALLATION_FILENAME = 'host-installation.json'
diff --git a/src/main/runtime/rpc/dispatcher-request-parsing.ts b/src/main/runtime/rpc/dispatcher-request-parsing.ts
index 35d213f9d79..fb4b6b7e5a4 100644
--- a/src/main/runtime/rpc/dispatcher-request-parsing.ts
+++ b/src/main/runtime/rpc/dispatcher-request-parsing.ts
@@ -1,4 +1,4 @@
-import { getCompiledSchema } from '../../zod-schema-compilation'
+import { getCompiledSchema } from '../../schema-validation/zod-schema-compilation'
 import {
   formatZodError,
   type RpcAnyMethodDeclaration,
diff --git a/src/main/runtime/runtime-failed-local-worktree-removal.test.ts b/src/main/runtime/runtime-failed-local-worktree-removal.test.ts
index d85d4b8885e..e4c8a7233e3 100644
--- a/src/main/runtime/runtime-failed-local-worktree-removal.test.ts
+++ b/src/main/runtime/runtime-failed-local-worktree-removal.test.ts
@@ -12,8 +12,8 @@ import type { Repo } from '../../shared/repo-types'
 import type { GitPushTarget } from '../../shared/worktree/types'
 import { removeTree } from '../../shared/windows-transient-lock-removal'
 import type { Store } from '../persistence/loading-store/store'
-import type * as HostTreeRemoval from '../host-tree-removal'
-import { removeHostTree } from '../host-tree-removal'
+import type * as HostTreeRemoval from '../filesystem/host-tree-removal'
+import { removeHostTree } from '../filesystem/host-tree-removal'
 import { listWorktreesStrict, removeWorktree } from '../git/worktree'
 import { areWorktreePathsEqual } from '../git/worktree-path-comparison'
 import { acquireWatcherRemovalGate, beginTerminalInstall } from '../ipc/watcher-removal-gate'
@@ -40,7 +40,7 @@ import type { RuntimeStore } from './runtime-store-contract'
 vi.mock('../project-runtime-git-options', () => ({
   getLocalProjectWorktreeGitOptions: () => ({})
 }))
-vi.mock('../host-tree-removal', async (importOriginal) => {
+vi.mock('../filesystem/host-tree-removal', async (importOriginal) => {
   const actual = await importOriginal<typeof HostTreeRemoval>()
   return { ...actual, removeHostTree: vi.fn(actual.removeHostTree) }
 })
diff --git a/src/main/runtime/runtime-interrupted-local-worktree-removal.test.ts b/src/main/runtime/runtime-interrupted-local-worktree-removal.test.ts
index 85a4f3e9ce2..1551d3aeeff 100644
--- a/src/main/runtime/runtime-interrupted-local-worktree-removal.test.ts
+++ b/src/main/runtime/runtime-interrupted-local-worktree-removal.test.ts
@@ -15,9 +15,9 @@ import { buildDetectedGitWorktrees } from '../ipc/worktrees/listing/ssh-worktree
 import { removeTree } from '../../shared/windows-transient-lock-removal'
 import type { RemoveWorktreeResult } from '../../shared/worktree/create-types'
 import type { Store } from '../persistence/loading-store/store'
-import type * as HostTreeRemoval from '../host-tree-removal'
-import { removeHostTree } from '../host-tree-removal'
-import * as nativeFs from '../asar-transparent-fs'
+import type * as HostTreeRemoval from '../filesystem/host-tree-removal'
+import { removeHostTree } from '../filesystem/host-tree-removal'
+import * as nativeFs from '../filesystem/asar-transparent-fs'
 import * as diskFs from 'node:fs/promises'
 import * as nativeRemoval from '../git/windows-worktree-removal'
 import * as graphReader from '../git/worktree-list-reader'
@@ -63,7 +63,7 @@ vi.mock('node:fs/promises', async (importOriginal) => {
 vi.mock('../project-runtime-git-options', () => ({
   getLocalProjectWorktreeGitOptions: vi.fn(() => ({}))
 }))
-vi.mock('../host-tree-removal', async (importOriginal) => {
+vi.mock('../filesystem/host-tree-removal', async (importOriginal) => {
   const actual = await importOriginal<typeof HostTreeRemoval>()
   return { ...actual, removeHostTree: vi.fn(actual.removeHostTree) }
 })
diff --git a/src/main/zod-schema-compilation.test.ts b/src/main/schema-validation/zod-schema-compilation.test.ts
similarity index 100%
rename from src/main/zod-schema-compilation.test.ts
rename to src/main/schema-validation/zod-schema-compilation.test.ts
diff --git a/src/main/zod-schema-compilation.ts b/src/main/schema-validation/zod-schema-compilation.ts
similarity index 100%
rename from src/main/zod-schema-compilation.ts
rename to src/main/schema-validation/zod-schema-compilation.ts
diff --git a/src/main/skills/skill-package-tar.ts b/src/main/skills/skill-package-tar.ts
index 99fad1417cb..c4d58db0ec0 100644
--- a/src/main/skills/skill-package-tar.ts
+++ b/src/main/skills/skill-package-tar.ts
@@ -7,7 +7,11 @@ import { pipeline } from 'node:stream/promises'
 import { createGunzip } from 'node:zlib'
 import { SKILL_PACKAGE_MAX_COMPRESSED_BYTES } from '../../shared/skill-package-manifest'
 import { createDeterministicGzipStore } from './skill-package-deterministic-gzip'
-import { buildUstarEntryHeader, USTAR_BLOCK_BYTES, ustarPaddingBytes } from '../ustar-entry-header'
+import {
+  buildUstarEntryHeader,
+  USTAR_BLOCK_BYTES,
+  ustarPaddingBytes
+} from '../archive/ustar-entry-header'
 
 const TAR_BLOCK_BYTES = USTAR_BLOCK_BYTES
 const TAR_EXPANDED_LIMIT = 40 * 1024 * 1024
diff --git a/src/main/speech/openai-api-key-store.ts b/src/main/speech/openai-api-key-store.ts
index 66c943a35a1..e93a2eb9577 100644
--- a/src/main/speech/openai-api-key-store.ts
+++ b/src/main/speech/openai-api-key-store.ts
@@ -1,5 +1,5 @@
 import { getSecretStore } from '../../shared/secret-store'
-import { readCredentialFileProtection } from '../credential-file-protection'
+import { readCredentialFileProtection } from '../credentials/credential-file-protection'
 import {
   classifyUnenvelopedCredential,
   type SecretAtRestProtection
diff --git a/src/main/speech/stt-worker-paths.ts b/src/main/speech/stt-worker-paths.ts
index 96964f05277..90a6c8432f0 100644
--- a/src/main/speech/stt-worker-paths.ts
+++ b/src/main/speech/stt-worker-paths.ts
@@ -5,7 +5,10 @@ import {
   SPEECH_RECOGNIZER_DIR_ENV,
   speechRecognizerPackageName
 } from '../../shared/speech-recognizer-package'
-import { currentWorkerEntryLayout, resolveWorkerThreadEntryPath } from '../worker-thread-entry-path'
+import {
+  currentWorkerEntryLayout,
+  resolveWorkerThreadEntryPath
+} from '../worker-threads/worker-thread-entry-path'
 
 /** Mobile maps voice_model_not_ready: to host-supported model setup, including hosts with no recognizer. */
 export const LOCAL_SPEECH_UNAVAILABLE_ERROR = 'voice_model_not_ready:unavailable'
diff --git a/src/main/ssh/legacy-relay/legacy-relay-cli-call-limits.ts b/src/main/ssh/legacy-relay/legacy-relay-cli-call-limits.ts
index 02e33739d78..9c983a3e9f3 100644
--- a/src/main/ssh/legacy-relay/legacy-relay-cli-call-limits.ts
+++ b/src/main/ssh/legacy-relay/legacy-relay-cli-call-limits.ts
@@ -12,7 +12,7 @@ import {
   readPromptBasePayloadHash,
   replayStableCallerParams
 } from '../../runtime/rpc/orchestration-mutation-receipt'
-import { getCompiledSchema } from '../../zod-schema-compilation'
+import { getCompiledSchema } from '../../schema-validation/zod-schema-compilation'
 import type { LegacyRelayCliCall } from './legacy-relay-cli-caller'
 
 /** Enough for a coordinator and its workers' waits; past it a host is flooding this desktop. */
diff --git a/src/main/ssh/ssh-host-key-store.ts b/src/main/ssh/ssh-host-key-store.ts
index 077f36394ca..75dd8fdecca 100644
--- a/src/main/ssh/ssh-host-key-store.ts
+++ b/src/main/ssh/ssh-host-key-store.ts
@@ -2,7 +2,7 @@
 import { createHash } from 'node:crypto'
 import { mkdir, readFile } from 'node:fs/promises'
 import { dirname, join } from 'node:path'
-import { withSidecarSnapshotQueue, writeSidecarSnapshot } from '../sidecar-snapshot-file'
+import { withSidecarSnapshotQueue, writeSidecarSnapshot } from '../filesystem/sidecar-snapshot-file'
 import {
   formatHostKeyFingerprint,
   readHostKeyType,
diff --git a/src/main/startup/http1-compatibility-marker.ts b/src/main/startup/http1-compatibility-marker.ts
index 968d805bc84..2ad797cf3a4 100644
--- a/src/main/startup/http1-compatibility-marker.ts
+++ b/src/main/startup/http1-compatibility-marker.ts
@@ -1,6 +1,6 @@
 import { readFileSync, rmSync } from 'node:fs'
 import { join } from 'node:path'
-import { durableWriteTempPath, writeFileDurableSync } from '../durable-file-write'
+import { durableWriteTempPath, writeFileDurableSync } from '../filesystem/durable-file-write'
 import { bestEffortFsyncDirectorySync } from '../../shared/secure-file'
 
 /** A tiny profile-scoped marker selects HTTP/2 before the first Electron session without reparsing multi-MB settings before Store startup. Profile identity prevents cross-profile reuse. */
diff --git a/src/main/startup/main-process-ready-identity-write.test.ts b/src/main/startup/main-process-ready-identity-write.test.ts
index bc79f45d03c..b17c962d15a 100644
--- a/src/main/startup/main-process-ready-identity-write.test.ts
+++ b/src/main/startup/main-process-ready-identity-write.test.ts
@@ -2,7 +2,7 @@ import { mkdtempSync, writeFileSync } from 'node:fs'
 import { tmpdir } from 'node:os'
 import { join } from 'node:path'
 import { afterEach, beforeAll, beforeEach, describe, expect, it, vi } from 'vitest'
-import type * as DurableFileWrite from '../durable-file-write'
+import type * as DurableFileWrite from '../filesystem/durable-file-write'
 import { JIRA_IMAGE_SCHEME } from '../../shared/jira/jira-attachment-image'
 
 const ORIGINAL_PLATFORM = process.platform
@@ -31,7 +31,7 @@ const mocks = vi.hoisted(() => ({
   writeFileDurableSync: vi.fn()
 }))
 
-vi.mock('../durable-file-write', async (importOriginal) => {
+vi.mock('../filesystem/durable-file-write', async (importOriginal) => {
   const actual = await importOriginal<typeof DurableFileWrite>()
   return {
     ...actual,
diff --git a/src/main/terminal-config-import/preview.ts b/src/main/terminal-config-import/preview.ts
index c2559db15b4..70f48fa757d 100644
--- a/src/main/terminal-config-import/preview.ts
+++ b/src/main/terminal-config-import/preview.ts
@@ -3,7 +3,7 @@ import type { WebContents } from 'electron'
 import type { GlobalSettings } from '../../shared/global-settings-types'
 import type { TerminalConfigImportPreview } from '../../shared/terminal-config-import-preview'
 import type { Store } from '../persistence/loading-store/store'
-import { validateImportSource } from '../import-source-validation'
+import { validateImportSource } from '../configuration-import/import-source-validation'
 import { chooseTerminalConfigFile } from './choose-config-file'
 import { settingsChanges } from './settings-changes'
 
diff --git a/src/main/terminal-history-deletion.ts b/src/main/terminal-history-deletion.ts
index d0409591021..fe05fc42365 100644
--- a/src/main/terminal-history-deletion.ts
+++ b/src/main/terminal-history-deletion.ts
@@ -1,7 +1,7 @@
 import { basename, dirname, join } from 'node:path'
 import { existsSync, mkdirSync, renameSync } from 'node:fs'
 import { readdir } from 'node:fs/promises'
-import { removeHostTree } from './host-tree-removal'
+import { removeHostTree } from './filesystem/host-tree-removal'
 import { deleteFishHistoryFile, resolveFishHistoryDir } from './fish-history-session'
 import { readHistoryMeta } from './terminal-history'
 import {
diff --git a/src/main/terminal-history-gc-fs-call-count.test.ts b/src/main/terminal-history-gc-fs-call-count.test.ts
index 4e367ac41c2..362f38eae7f 100644
--- a/src/main/terminal-history-gc-fs-call-count.test.ts
+++ b/src/main/terminal-history-gc-fs-call-count.test.ts
@@ -19,7 +19,7 @@ const { fsCalls, removeHostTreeMock } = vi.hoisted(() => ({
   removeHostTreeMock: vi.fn<(dir: string) => Promise<void>>()
 }))
 
-vi.mock('./host-tree-removal', () => ({ removeHostTree: removeHostTreeMock }))
+vi.mock('./filesystem/host-tree-removal', () => ({ removeHostTree: removeHostTreeMock }))
 
 // Count real filesystem calls so the measured I/O still reaches disk.
 vi.mock('node:fs/promises', async () => {
diff --git a/src/main/terminal-history-gc.test.ts b/src/main/terminal-history-gc.test.ts
index b4b09cf8917..50275b1fc2f 100644
--- a/src/main/terminal-history-gc.test.ts
+++ b/src/main/terminal-history-gc.test.ts
@@ -17,7 +17,7 @@ const { removeHostTreeMock } = vi.hoisted(() => ({
 }))
 
 // The stub must delete tombstones: reporting success while leaving them on disk loops the drain.
-vi.mock('./host-tree-removal', () => ({
+vi.mock('./filesystem/host-tree-removal', () => ({
   removeHostTree: removeHostTreeMock
 }))
 
diff --git a/src/main/terminal-history-tombstone-retry.test.ts b/src/main/terminal-history-tombstone-retry.test.ts
index ef860aafaea..df9ef097303 100644
--- a/src/main/terminal-history-tombstone-retry.test.ts
+++ b/src/main/terminal-history-tombstone-retry.test.ts
@@ -11,7 +11,7 @@ const { removeHostTreeMock, deleteWslFishHistoryFileMock } = vi.hoisted(() => ({
   deleteWslFishHistoryFileMock: vi.fn<(distro: string, session: string) => Promise<string | void>>()
 }))
 
-vi.mock('./host-tree-removal', () => ({
+vi.mock('./filesystem/host-tree-removal', () => ({
   removeHostTree: removeHostTreeMock
 }))
 
diff --git a/src/main/terminal-history-tombstone-scan-cost.test.ts b/src/main/terminal-history-tombstone-scan-cost.test.ts
index 5abbe290a33..91840bba812 100644
--- a/src/main/terminal-history-tombstone-scan-cost.test.ts
+++ b/src/main/terminal-history-tombstone-scan-cost.test.ts
@@ -30,7 +30,7 @@ vi.mock('node:fs/promises', async (importOriginal) => {
   }
 })
 
-vi.mock('./host-tree-removal', () => ({ removeHostTree: removeHostTreeMock }))
+vi.mock('./filesystem/host-tree-removal', () => ({ removeHostTree: removeHostTreeMock }))
 
 import {
   cancelPendingHistoryTreeRemovalRetries,
diff --git a/src/main/usage-cache-snapshot-writer.ts b/src/main/usage-cache-snapshot-writer.ts
index 08faf228351..a7908fa0d89 100644
--- a/src/main/usage-cache-snapshot-writer.ts
+++ b/src/main/usage-cache-snapshot-writer.ts
@@ -4,7 +4,7 @@ import {
   durableWriteTempPath,
   removeStaleDurableWriteTempFiles,
   writeFileDurableIfCurrent
-} from './durable-file-write'
+} from './filesystem/durable-file-write'
 
 // Serialize durable writes per store and skip superseded snapshots.
 export class UsageCacheSnapshotWriter {
diff --git a/src/main/usage/usage-scan-worker-cache-cleanup.test.ts b/src/main/usage/usage-scan-worker-cache-cleanup.test.ts
index aabf7d13b35..7e011fe775f 100644
--- a/src/main/usage/usage-scan-worker-cache-cleanup.test.ts
+++ b/src/main/usage/usage-scan-worker-cache-cleanup.test.ts
@@ -5,7 +5,7 @@ import { join, resolve } from 'node:path'
 import { Worker } from 'node:worker_threads'
 import { build } from 'esbuild'
 import { afterAll, beforeAll, describe, expect, it } from 'vitest'
-import { durableWriteTempPath } from '../durable-file-write'
+import { durableWriteTempPath } from '../filesystem/durable-file-write'
 import { createUsageScanWorkerTransport } from './usage-scan-worker-cache-cleanup'
 import type { UsageScanWorkerRequest } from './usage-scan-worker-protocol'
 import { usageSourceCachePath } from './usage-source-cache-file'
diff --git a/src/main/usage/usage-scan-worker-cache-cleanup.ts b/src/main/usage/usage-scan-worker-cache-cleanup.ts
index 9476d2b7a1a..d7486a62400 100644
--- a/src/main/usage/usage-scan-worker-cache-cleanup.ts
+++ b/src/main/usage/usage-scan-worker-cache-cleanup.ts
@@ -1,5 +1,8 @@
-import type { WorkerRequestTransport, WorkerThreadFactory } from '../lazy-worker-thread-host'
-import { removeStaleDurableWriteTempFiles } from '../durable-file-write'
+import type {
+  WorkerRequestTransport,
+  WorkerThreadFactory
+} from '../worker-threads/worker-thread-transport'
+import { removeStaleDurableWriteTempFiles } from '../filesystem/durable-file-write'
 import type { UsageScanWorkerRequest } from './usage-scan-worker-protocol'
 import { usageSourceCachePath } from './usage-source-cache-file'
 
diff --git a/src/main/usage/usage-scan-worker-client.ts b/src/main/usage/usage-scan-worker-client.ts
index 47b2bbea439..78940cfe1c0 100644
--- a/src/main/usage/usage-scan-worker-client.ts
+++ b/src/main/usage/usage-scan-worker-client.ts
@@ -1,5 +1,5 @@
-import { WorkerThreadRequestQueue } from '../worker-thread-request-queue'
-import type { WorkerThreadFactory } from '../lazy-worker-thread-host'
+import { WorkerThreadRequestQueue } from '../worker-threads/worker-thread-request-queue'
+import type { WorkerThreadFactory } from '../worker-threads/worker-thread-transport'
 import type { ClaudeUsageDailyAggregate, ClaudeUsageSession } from '../claude-usage/types'
 import type { CodexUsageDailyAggregate, CodexUsageSession } from '../codex-usage/types'
 import type { OpenCodeUsageDailyAggregate, OpenCodeUsageSession } from '../opencode-usage/types'
diff --git a/src/main/usage/usage-scan-worker-spawn.ts b/src/main/usage/usage-scan-worker-spawn.ts
index f49c1ded8d6..80711efdbf6 100644
--- a/src/main/usage/usage-scan-worker-spawn.ts
+++ b/src/main/usage/usage-scan-worker-spawn.ts
@@ -1,7 +1,10 @@
 import { claudeProfileTranscriptDirs } from '../claude-usage/transcript-file-discovery'
 import { existsSync } from 'node:fs'
 import { Worker } from 'node:worker_threads'
-import { currentWorkerEntryLayout, resolveWorkerThreadEntryPath } from '../worker-thread-entry-path'
+import {
+  currentWorkerEntryLayout,
+  resolveWorkerThreadEntryPath
+} from '../worker-threads/worker-thread-entry-path'
 import type { ClaudeUsageDailyAggregate, ClaudeUsageSession } from '../claude-usage/types'
 import type { CodexUsageDailyAggregate, CodexUsageSession } from '../codex-usage/types'
 import type { OpenCodeUsageDailyAggregate, OpenCodeUsageSession } from '../opencode-usage/types'
diff --git a/src/main/usage/usage-source-cache-file.ts b/src/main/usage/usage-source-cache-file.ts
index ae66cd36310..9c23a6c0db9 100644
--- a/src/main/usage/usage-source-cache-file.ts
+++ b/src/main/usage/usage-source-cache-file.ts
@@ -5,7 +5,7 @@ import {
   durableWriteTempPath,
   removeStaleDurableWriteTempFiles,
   writeFileDurable
-} from '../durable-file-write'
+} from '../filesystem/durable-file-write'
 
 // Only scans need bulky per-source records; worker-owned sidecars keep them off main.
 
diff --git a/src/main/warp-themes/index.ts b/src/main/warp-themes/index.ts
index da01eeb792d..f203a7f0df5 100644
--- a/src/main/warp-themes/index.ts
+++ b/src/main/warp-themes/index.ts
@@ -14,7 +14,7 @@ import {
   type PreviewOperationBudget,
   type WarpThemePreviewOptions
 } from './preview-operation-budget'
-import { validateImportSource } from '../import-source-validation'
+import { validateImportSource } from '../configuration-import/import-source-validation'
 import { filesFromAutoDirectories } from './auto-discovered-theme-files'
 import { filesFromDirectory, type ThemeSourceSelection } from './theme-source-selection'
 import {
diff --git a/src/main/window/project-move-pause.ts b/src/main/window/project-move-pause.ts
index 034a0089474..76121bdcf7d 100644
--- a/src/main/window/project-move-pause.ts
+++ b/src/main/window/project-move-pause.ts
@@ -7,7 +7,7 @@ import {
   type ProjectMovePauseResponse
 } from '../../shared/project-move-pause'
 import type { WorkspaceSleepOutcome, WorkspaceSleepRequest } from '../../shared/workspace-sleep'
-import { addFanoutListener, addFanoutListeners } from '../event-listener-fanout'
+import { addFanoutListener, addFanoutListeners } from '../runtime/events/event-listener-fanout'
 
 type SleepRuntime = {
   sleepWorkspaces: (request: WorkspaceSleepRequest) => Promise<WorkspaceSleepOutcome[]>
diff --git a/src/main/window/session-tab-close-request-relay.ts b/src/main/window/session-tab-close-request-relay.ts
index 834da75f24f..e9564342bdc 100644
--- a/src/main/window/session-tab-close-request-relay.ts
+++ b/src/main/window/session-tab-close-request-relay.ts
@@ -7,7 +7,7 @@ import type {
   SessionTabCloseResponse
 } from '../../shared/session-tab-close'
 import { SESSION_TAB_CLOSE_TIMEOUT_ERROR } from '../../shared/session-tab-close'
-import { addFanoutListener, addFanoutListeners } from '../event-listener-fanout'
+import { addFanoutListener, addFanoutListeners } from '../runtime/events/event-listener-fanout'
 
 const SESSION_TAB_CLOSE_CONFIRMATION_MS = 5 * 60_000
 const SESSION_TAB_CLOSE_RESPONSE_GRACE_MS = 5_000
diff --git a/src/main/window/terminal-pane-reveal-relay.ts b/src/main/window/terminal-pane-reveal-relay.ts
index 57a4d1871ee..74acc5a80f7 100644
--- a/src/main/window/terminal-pane-reveal-relay.ts
+++ b/src/main/window/terminal-pane-reveal-relay.ts
@@ -6,7 +6,7 @@ import type {
   TerminalPaneRevealReply,
   TerminalPaneRevealTarget
 } from '../../shared/terminal-pane-reveal'
-import { addFanoutListener } from '../event-listener-fanout'
+import { addFanoutListener } from '../runtime/events/event-listener-fanout'
 import { abortWhenRendererGone } from '../ipc/renderer-lifetime-abort'
 import { focusExistingMainWindow } from './focus-existing-window'
 
diff --git a/src/main/window/terminal-tab-close-request-relay.ts b/src/main/window/terminal-tab-close-request-relay.ts
index b3b7d6d7a65..df2d46d0ec5 100644
--- a/src/main/window/terminal-tab-close-request-relay.ts
+++ b/src/main/window/terminal-tab-close-request-relay.ts
@@ -6,7 +6,7 @@ import type {
   TerminalTabCloseRequest,
   TerminalTabCloseResponse
 } from '../../shared/terminal-tab-close'
-import { addFanoutListener, addFanoutListeners } from '../event-listener-fanout'
+import { addFanoutListener, addFanoutListeners } from '../runtime/events/event-listener-fanout'
 
 const TERMINAL_TAB_CLOSE_TIMEOUT_MS = 20_000
 
diff --git a/src/main/worker-thread-child-process/worker-thread-child-process.ts b/src/main/worker-thread-child-process/worker-thread-child-process.ts
index b21c0fec975..f3a6526288b 100644
--- a/src/main/worker-thread-child-process/worker-thread-child-process.ts
+++ b/src/main/worker-thread-child-process/worker-thread-child-process.ts
@@ -1,8 +1,12 @@
 import { EventEmitter } from 'node:events'
 import { existsSync } from 'node:fs'
 import { Worker } from 'node:worker_threads'
-import { LazyWorkerThreadHost, type WorkerThreadFactory } from '../lazy-worker-thread-host'
-import { currentWorkerEntryLayout, resolveWorkerThreadEntryPath } from '../worker-thread-entry-path'
+import { LazyWorkerThreadHost } from '../worker-threads/lazy-worker-thread-host'
+import type { WorkerThreadFactory } from '../worker-threads/worker-thread-transport'
+import {
+  currentWorkerEntryLayout,
+  resolveWorkerThreadEntryPath
+} from '../worker-threads/worker-thread-entry-path'
 import type {
   WorkerThreadChildErrorPayload,
   WorkerThreadChildEvent,
diff --git a/src/main/forked-child-entry-path.ts b/src/main/worker-threads/forked-child-entry-path.ts
similarity index 95%
rename from src/main/forked-child-entry-path.ts
rename to src/main/worker-threads/forked-child-entry-path.ts
index 37e901c702a..3fdbb0e57fc 100644
--- a/src/main/forked-child-entry-path.ts
+++ b/src/main/worker-threads/forked-child-entry-path.ts
@@ -1,6 +1,6 @@
 import { existsSync } from 'node:fs'
 import { join } from 'node:path'
-import { getAppEnvironment, hasAppEnvironment } from '../shared/app-environment'
+import { getAppEnvironment, hasAppEnvironment } from '../../shared/app-environment'
 
 /** Plain-Node entries import this module; the build guard rejects literal Electron requires. */
 export function resolveForkedChildEntryPath(
diff --git a/src/main/lazy-worker-thread-host.ts b/src/main/worker-threads/lazy-worker-thread-host.ts
similarity index 97%
rename from src/main/lazy-worker-thread-host.ts
rename to src/main/worker-threads/lazy-worker-thread-host.ts
index 5b674f1c083..a3a0f5ea464 100644
--- a/src/main/lazy-worker-thread-host.ts
+++ b/src/main/worker-threads/lazy-worker-thread-host.ts
@@ -1,5 +1,4 @@
 import type { WorkerRequestTransport, WorkerThreadFactory } from './worker-thread-transport'
-export type { WorkerRequestTransport, WorkerThreadFactory } from './worker-thread-transport'
 
 /** Clients own request state and must fail queued calls when spawning fails. */
 export class LazyWorkerThreadHost<TResponse> {
diff --git a/src/main/worker-thread-entry-path.ts b/src/main/worker-threads/worker-thread-entry-path.ts
similarity index 94%
rename from src/main/worker-thread-entry-path.ts
rename to src/main/worker-threads/worker-thread-entry-path.ts
index 2673114ad5a..b269fd6dd62 100644
--- a/src/main/worker-thread-entry-path.ts
+++ b/src/main/worker-threads/worker-thread-entry-path.ts
@@ -1,5 +1,5 @@
 import { basename, dirname, join } from 'node:path'
-import { getAppEnvironment, hasAppEnvironment } from '../shared/app-environment'
+import { getAppEnvironment, hasAppEnvironment } from '../../shared/app-environment'
 
 /** Keep this reachable from plain-Node entries; the build guard rejects Electron imports here. */
 export type WorkerEntryLayout = {
diff --git a/src/main/worker-thread-request-queue.test.ts b/src/main/worker-threads/worker-thread-request-queue.test.ts
similarity index 100%
rename from src/main/worker-thread-request-queue.test.ts
rename to src/main/worker-threads/worker-thread-request-queue.test.ts
diff --git a/src/main/worker-thread-request-queue.ts b/src/main/worker-threads/worker-thread-request-queue.ts
similarity index 98%
rename from src/main/worker-thread-request-queue.ts
rename to src/main/worker-threads/worker-thread-request-queue.ts
index 4b4eec256af..702e88a3a82 100644
--- a/src/main/worker-thread-request-queue.ts
+++ b/src/main/worker-threads/worker-thread-request-queue.ts
@@ -1,4 +1,5 @@
-import { LazyWorkerThreadHost, type WorkerThreadFactory } from './lazy-worker-thread-host'
+import { LazyWorkerThreadHost } from './lazy-worker-thread-host'
+import type { WorkerThreadFactory } from './worker-thread-transport'
 
 /** Serialize worker calls; failures must never move their work onto the main thread. */
 
diff --git a/src/main/worker-thread-transport.ts b/src/main/worker-threads/worker-thread-transport.ts
similarity index 100%
rename from src/main/worker-thread-transport.ts
rename to src/main/worker-threads/worker-thread-transport.ts
diff --git a/src/main/workspaces/cleanup/workspace-cleanup-scan-snapshot.test.ts b/src/main/workspaces/cleanup/workspace-cleanup-scan-snapshot.test.ts
index dce2ebd319c..2186205ff05 100644
--- a/src/main/workspaces/cleanup/workspace-cleanup-scan-snapshot.test.ts
+++ b/src/main/workspaces/cleanup/workspace-cleanup-scan-snapshot.test.ts
@@ -12,7 +12,7 @@ const { snapshotWriteSpy, userDataDirHolder } = vi.hoisted(() => ({
   userDataDirHolder: { dir: '' }
 }))
 
-vi.mock('../../sidecar-snapshot-file', async (importOriginal) => {
+vi.mock('../../filesystem/sidecar-snapshot-file', async (importOriginal) => {
   const actual = await importOriginal<Record<string, unknown>>()
   const writeSidecarSnapshot = actual.writeSidecarSnapshot as (
     file: string,
diff --git a/src/main/workspaces/cleanup/workspace-cleanup-scan-snapshot.ts b/src/main/workspaces/cleanup/workspace-cleanup-scan-snapshot.ts
index 6e54bd68164..78b4a9966d0 100644
--- a/src/main/workspaces/cleanup/workspace-cleanup-scan-snapshot.ts
+++ b/src/main/workspaces/cleanup/workspace-cleanup-scan-snapshot.ts
@@ -9,7 +9,7 @@ import {
   sidecarSnapshotFile,
   withSidecarSnapshotQueue,
   writeSidecarSnapshot
-} from '../../sidecar-snapshot-file'
+} from '../../filesystem/sidecar-snapshot-file'
 import type { ExecutionHostId } from '../../../shared/execution-host'
 import {
   activeWorkspaceSnapshotPruneKeys,
diff --git a/src/main/workspaces/space-analysis/workspace-space-analysis-snapshot.test.ts b/src/main/workspaces/space-analysis/workspace-space-analysis-snapshot.test.ts
index 9fcd07b7b2a..9321a6d62b2 100644
--- a/src/main/workspaces/space-analysis/workspace-space-analysis-snapshot.test.ts
+++ b/src/main/workspaces/space-analysis/workspace-space-analysis-snapshot.test.ts
@@ -12,7 +12,7 @@ const { snapshotWriteSpy, userDataDirHolder } = vi.hoisted(() => ({
   userDataDirHolder: { dir: '' }
 }))
 
-vi.mock('../../sidecar-snapshot-file', async (importOriginal) => {
+vi.mock('../../filesystem/sidecar-snapshot-file', async (importOriginal) => {
   const actual = await importOriginal<Record<string, unknown>>()
   const writeSidecarSnapshot = actual.writeSidecarSnapshot as (
     file: string,
diff --git a/src/main/workspaces/space-analysis/workspace-space-analysis-snapshot.ts b/src/main/workspaces/space-analysis/workspace-space-analysis-snapshot.ts
index f87a8d8bdd0..d1fe7e64181 100644
--- a/src/main/workspaces/space-analysis/workspace-space-analysis-snapshot.ts
+++ b/src/main/workspaces/space-analysis/workspace-space-analysis-snapshot.ts
@@ -7,7 +7,7 @@ import {
   sidecarSnapshotFile,
   withSidecarSnapshotQueue,
   writeSidecarSnapshot
-} from '../../sidecar-snapshot-file'
+} from '../../filesystem/sidecar-snapshot-file'
 import type { ExecutionHostId } from '../../../shared/execution-host'
 import {
   activeWorkspaceSnapshotPruneKeys,
diff --git a/src/main/workspaces/space-analysis/workspace-space-scan-worker-client.ts b/src/main/workspaces/space-analysis/workspace-space-scan-worker-client.ts
index 4f52b7ea3e7..bd81a405c12 100644
--- a/src/main/workspaces/space-analysis/workspace-space-scan-worker-client.ts
+++ b/src/main/workspaces/space-analysis/workspace-space-scan-worker-client.ts
@@ -3,11 +3,11 @@ import { Worker } from 'node:worker_threads'
 import type { Repo } from '../../../shared/repo-types'
 import type { Worktree } from '../../../shared/worktree/types'
 import type { WorkspaceSpaceWorktree } from '../../../shared/workspace-space-types'
-import { WorkerThreadRequestQueue } from '../../worker-thread-request-queue'
+import { WorkerThreadRequestQueue } from '../../worker-threads/worker-thread-request-queue'
 import {
   currentWorkerEntryLayout,
   resolveWorkerThreadEntryPath
-} from '../../worker-thread-entry-path'
+} from '../../worker-threads/worker-thread-entry-path'
 import type {
   WorkspaceSpaceScanWorkerRequest,
   WorkspaceSpaceScanWorkerResponse
diff --git a/src/main/worktree-create-preparation-pool.ts b/src/main/worktree-create-preparation-pool.ts
index 1f8c8ea0ac6..68713b327fc 100644
--- a/src/main/worktree-create-preparation-pool.ts
+++ b/src/main/worktree-create-preparation-pool.ts
@@ -11,7 +11,7 @@ import type { AddWorktreeOptions } from './git/worktree'
 import { prepareWorktreeCreateCheckout } from './git/worktree-create-preparation'
 import { WorktreePreparationLockOwnershipError } from './git/worktree-preparation-lock'
 import { queuePreparedWorktreeTipRefresh } from './worktree-preparation-refresh-queue'
-import { toHostFilesystemPath } from './host-tree-removal'
+import { toHostFilesystemPath } from './filesystem/host-tree-removal'
 import { createPreparationActivity } from './worktree-create-preparation-activity'
 import { profileStateAccessMachineIdentity } from './persistence/profile-state/profile-state-access-identity'
 import type { PreparationActivity } from './worktree-create-preparation-activity'
diff --git a/src/main/worktree-create-preparation.ts b/src/main/worktree-create-preparation.ts
index 0f3e25a5948..24bedb77b3e 100644
--- a/src/main/worktree-create-preparation.ts
+++ b/src/main/worktree-create-preparation.ts
@@ -40,7 +40,7 @@ import {
   recordPreparationConsume,
   resetPreparationConsumeHistoryForTests
 } from './worktree-create-preparation-burst'
-import { toHostFilesystemPath } from './host-tree-removal'
+import { toHostFilesystemPath } from './filesystem/host-tree-removal'
 import type { WorktreeCreateTimingRecorder } from './worktree-create-timing'
 
 export {
diff --git a/src/main/worktree-removal-records.ts b/src/main/worktree-removal-records.ts
index bb739870d81..33c55d9c48e 100644
--- a/src/main/worktree-removal-records.ts
+++ b/src/main/worktree-removal-records.ts
@@ -4,7 +4,7 @@ import {
   sidecarSnapshotFile,
   withSidecarSnapshotQueue,
   writeSidecarSnapshot
-} from './sidecar-snapshot-file'
+} from './filesystem/sidecar-snapshot-file'
 
 const RECORDS_FILE_NAME = 'orca-worktree-removals.json'
 const RECORDS_VERSION = 1
diff --git a/src/main/worktree-trash.ts b/src/main/worktree-trash.ts
index 750840d571f..ae71909bbb3 100644
--- a/src/main/worktree-trash.ts
+++ b/src/main/worktree-trash.ts
@@ -2,7 +2,7 @@
 
 import { lstat, readdir, rmdir } from 'node:fs/promises'
 import { join } from 'node:path'
-import { removeHostTree } from './host-tree-removal'
+import { removeHostTree } from './filesystem/host-tree-removal'
 import { isFolderRepo } from '../shared/repo-kind'
 import { computeWorkspaceRoot, getWorktreePathSettings } from './ipc/worktree-logic'
 import type { GlobalSettings } from '../shared/global-settings-types'
diff --git a/src/main/wsl/wsl-directory-upload.ts b/src/main/wsl/wsl-directory-upload.ts
index 491e8138a6f..0983dbb91a3 100644
--- a/src/main/wsl/wsl-directory-upload.ts
+++ b/src/main/wsl/wsl-directory-upload.ts
@@ -13,7 +13,11 @@ import {
   collectLocalUploadPlan,
   type LocalUploadPlan
 } from '../ssh/system-transport/system-ssh-file-transfer'
-import { buildUstarEntryHeader, USTAR_BLOCK_BYTES, ustarPaddingBytes } from '../ustar-entry-header'
+import {
+  buildUstarEntryHeader,
+  USTAR_BLOCK_BYTES,
+  ustarPaddingBytes
+} from '../archive/ustar-entry-header'
 
 export const WSL_GUEST_SOURCE_UNAVAILABLE = 'ORCA_WSL_GUEST_SOURCE_UNAVAILABLE'
 export const WSL_UPLOAD_PROMOTED = 'ORCA_WSL_UPLOAD_PROMOTED'
diff --git a/src/main/wsl/wsl-distro-holder-record.ts b/src/main/wsl/wsl-distro-holder-record.ts
index 959ec4c7be8..86399d64a2e 100644
--- a/src/main/wsl/wsl-distro-holder-record.ts
+++ b/src/main/wsl/wsl-distro-holder-record.ts
@@ -4,7 +4,7 @@ import {
   durableWriteTempPath,
   removeStaleDurableWriteTempFiles,
   writeFileDurable
-} from '../durable-file-write'
+} from '../filesystem/durable-file-write'
 import { hasErrorCode } from '../daemon/daemon-process-inspection'
 
 /** Per-distro record intentionally survives Orca quit so the next launch can re-adopt the surviving holder. */
diff --git a/src/main/wsl/wsl-drive-unc-conversion-stores.ts b/src/main/wsl/wsl-drive-unc-conversion-stores.ts
index 3673f9a4cbe..722e5d60742 100644
--- a/src/main/wsl/wsl-drive-unc-conversion-stores.ts
+++ b/src/main/wsl/wsl-drive-unc-conversion-stores.ts
@@ -12,7 +12,7 @@ import {
   durableWriteTempPath,
   syncDirectoryDurablySync,
   writeFileDurableSync
-} from '../durable-file-write'
+} from '../filesystem/durable-file-write'
 import { rewriteWslMoveOrchestrationHistoryFile } from '../persistence/moving-wsl-projects/wsl-move-orchestration-history-rewrite'
 import Database from '../sqlite/sync-database'
 import { hashWorktreeId } from '../terminal-history-id'
diff --git a/src/main/wsl/wsl-unc-drive-file-content.test.ts b/src/main/wsl/wsl-unc-drive-file-content.test.ts
index 4d822cbb0aa..056f6c20f66 100644
--- a/src/main/wsl/wsl-unc-drive-file-content.test.ts
+++ b/src/main/wsl/wsl-unc-drive-file-content.test.ts
@@ -85,7 +85,7 @@ vi.mock('node:fs/promises', async (importOriginal) => ({
 import { readLocalFileContent } from '../ipc/filesystem/filesystem-file-content-inspection'
 import { readLocalFileRange } from '../ipc/filesystem/local-file-range-read'
 import { writeLocalTextFileWithDiskPrecondition } from '../ipc/filesystem/local-disk-write-precondition'
-import { renameLocalPathSerializedByDestination } from '../destination-serialized-local-rename'
+import { renameLocalPathSerializedByDestination } from '../filesystem/destination-serialized-local-rename'
 
 const UNC = String.raw`\\wsl.localhost\Ubuntu\mnt\c\src\app`
 const originalPlatform = process.platform
diff --git a/src/shared/windows-private-credential-file.test.ts b/src/shared/windows-private-credential-file.test.ts
index 4ba999dc85f..20536032a38 100644
--- a/src/shared/windows-private-credential-file.test.ts
+++ b/src/shared/windows-private-credential-file.test.ts
@@ -8,7 +8,7 @@ import {
   setWindowsSecurityForTests
 } from './windows-security-addon'
 import { readPrivateWindowsFile } from './secure-path-windows-acl'
-import { writeCredentialFileAtomic } from '../main/integration-credential-file'
+import { writeCredentialFileAtomic } from '../main/credentials/integration-credential-file'
 
 const roots: string[] = []
 afterEach(() => {