From a9b9dfbe99b7b809a5e2435a6270fafa17a3173e Mon Sep 17 00:00:00 2001
From: Brennan Benson <79079362+brennanb2025@users.noreply.github.com>
Date: Sat, 1 Aug 2026 05:29:50 -0700
Subject: [PATCH] fix(pty): preserve byte-exact reservation paths

---
 src/shared/stable-pane-id.test.ts | 58 ++++++++++++++++++++++++-------
 src/shared/stable-pane-id.ts      | 22 ++++++++----
 2 files changed, 62 insertions(+), 18 deletions(-)

diff --git a/src/shared/stable-pane-id.test.ts b/src/shared/stable-pane-id.test.ts
index 5d8557feff7..0336ef696a4 100644
--- a/src/shared/stable-pane-id.test.ts
+++ b/src/shared/stable-pane-id.test.ts
@@ -9,6 +9,20 @@ import {
 } from './stable-pane-id'
 
 const LEAF_ID = '11111111-1111-4111-8111-111111111111'
+const PANE_KEY = makePaneKey('tab-1', LEAF_ID)
+
+function reservationKey(
+  workspaceId: string,
+  scope: { connectionId?: string; executionRuntime?: string } = {}
+) {
+  return makePaneSpawnReservationKey({
+    paneKey: PANE_KEY,
+    providerId: 'provider-1',
+    workspaceId,
+    sessionId: 'session-1',
+    ...scope
+  })
+}
 
 describe('stable pane ids', () => {
   it('recognizes UUID leaf ids as stable pane ids', () => {
@@ -57,30 +71,50 @@ describe('stable pane ids', () => {
     expect(parseLegacyNumericPaneKey('tab:1:12')).toBeNull()
   })
 
-  it('canonicalizes worktree aliases without collapsing independent PTY scopes', () => {
-    const paneKey = makePaneKey('tab-1', LEAF_ID)
+  it.each([
+    ['local', { executionRuntime: 'native' }],
+    ['SSH', { connectionId: 'ssh-1' }]
+  ])('keeps NFC and NFD POSIX workspace paths distinct on %s', (_label, scope) => {
+    expect(reservationKey('repo-1::/workspaces/café', scope)).not.toBe(
+      reservationKey('repo-1::/workspaces/cafe\u0301', scope)
+    )
+  })
+
+  it.each([
+    ['drive', 'repo-1::C:\\Work\\Project\\', 'repo-1::c:/work/project'],
+    ['UNC', 'repo-1::\\\\Server\\Share\\Project\\', 'repo-1:://server/share/project'],
+    [
+      'WSL UNC',
+      'repo-1::\\\\wsl.localhost\\Ubuntu\\home\\Project',
+      'repo-1:://wsl$/ubuntu/home/Project'
+    ]
+  ])('canonicalizes equivalent Windows %s paths', (_label, left, right) => {
+    expect(reservationKey(left)).toBe(reservationKey(right))
+  })
+
+  it('canonicalizes raw and worktree-scoped aliases', () => {
+    expect(reservationKey('repo-1::/workspaces/project')).toBe(
+      reservationKey('worktree:repo-1::/workspaces/project')
+    )
+  })
+
+  it('does not collapse independent PTY scopes', () => {
     const base = {
-      paneKey,
+      paneKey: PANE_KEY,
       providerId: 'provider-1',
       connectionId: 'ssh-1',
       executionRuntime: 'wsl:Ubuntu',
-      workspaceId: 'worktree:repo-1::C:\\Work\\Project\\',
+      workspaceId: 'worktree:repo-1::/workspaces/project',
       sessionId: 'session-1'
     }
     const canonical = makePaneSpawnReservationKey(base)
 
-    expect(canonical).toBe(
-      makePaneSpawnReservationKey({
-        ...base,
-        workspaceId: 'repo-1::c:/work/project'
-      })
-    )
     for (const distinct of [
       { providerId: 'provider-2' },
       { connectionId: 'ssh-2' },
       { executionRuntime: 'native' },
-      { workspaceId: 'repo-1::C:\\Work\\Other' },
-      { workspaceId: 'folder:repo-1::C:\\Work\\Project' },
+      { workspaceId: 'repo-1::/workspaces/other' },
+      { workspaceId: 'folder:repo-1::/workspaces/project' },
       { sessionId: 'session-2' }
     ]) {
       expect(makePaneSpawnReservationKey({ ...base, ...distinct })).not.toBe(canonical)
diff --git a/src/shared/stable-pane-id.ts b/src/shared/stable-pane-id.ts
index 3d1480c2c2d..858d6c95ffb 100644
--- a/src/shared/stable-pane-id.ts
+++ b/src/shared/stable-pane-id.ts
@@ -1,4 +1,4 @@
-import { normalizeRuntimePathForComparison } from './cross-platform-path'
+import { isWindowsAbsolutePathLike, normalizeRuntimePathSeparators } from './cross-platform-path'
 import { parseWorkspaceKey } from './workspace-scope'
 import { splitWorktreeId } from './worktree-id'
 
@@ -37,22 +37,32 @@ export function makePaneKey(tabId: string, stableLeafId: string): PaneKey {
   return `${tabId}:${stableLeafId}` as PaneKey
 }
 
+function canonicalPaneReservationWorkspacePath(worktreePath: string): string {
+  // Why: POSIX and SSH paths can be byte-sensitive; fold only syntactically proven Windows paths.
+  if (!isWindowsAbsolutePathLike(worktreePath)) {
+    return worktreePath
+  }
+  const normalized = normalizeRuntimePathSeparators(worktreePath)
+  const trimmed = /^[A-Za-z]:\/$/.test(normalized) ? normalized : normalized.replace(/\/+$/, '')
+  const wslUnc = trimmed.match(/^\/\/(?:wsl\.localhost|wsl\$)\/([^/]+)(\/[\s\S]*)?$/i)
+  return wslUnc ? `//wsl/${wslUnc[1].toLowerCase()}${wslUnc[2] ?? ''}` : trimmed.toLowerCase()
+}
+
 function canonicalWorkspaceIdentity(workspaceId: string): readonly string[] | null {
-  const trimmed = workspaceId.trim()
-  if (!trimmed || trimmed.length > 1024) {
+  if (!workspaceId.trim() || workspaceId.length > 1024) {
     return null
   }
-  const scope = parseWorkspaceKey(trimmed)
+  const scope = parseWorkspaceKey(workspaceId)
   const kind = scope?.type ?? 'worktree'
   const unscopedId =
     scope?.type === 'worktree'
       ? scope.worktreeId
       : scope?.type === 'folder'
         ? scope.folderWorkspaceId
-        : trimmed
+        : workspaceId
   const parsed = splitWorktreeId(unscopedId)
   return parsed
-    ? [kind, parsed.repoId, normalizeRuntimePathForComparison(parsed.worktreePath)]
+    ? [kind, parsed.repoId, canonicalPaneReservationWorkspacePath(parsed.worktreePath)]
     : [kind, unscopedId]
 }