diff --git a/src/main/github/client-pr-check-details.test.ts b/src/main/github/client-pr-check-details.test.ts
index ff210f7bc7e..df924954886 100644
--- a/src/main/github/client-pr-check-details.test.ts
+++ b/src/main/github/client-pr-check-details.test.ts
@@ -1,4 +1,5 @@
 import { beforeEach, describe, expect, it, vi } from 'vitest'
+import type * as GithubEnterpriseRepositoryModule from './github-enterprise-repository'
 
 const { ghExecFileAsyncMock, getOwnerRepoMock, rateLimitGuardMock } = vi.hoisted(() => ({
   ghExecFileAsyncMock: vi.fn(),
@@ -26,6 +27,11 @@ vi.mock('../git/runner', () => ({
   gitExecFileAsync: vi.fn()
 }))
 
+vi.mock('./github-enterprise-repository', async (importOriginal) => ({
+  ...(await importOriginal<typeof GithubEnterpriseRepositoryModule>()),
+  isGitHubHostAuthenticated: vi.fn().mockResolvedValue(true)
+}))
+
 vi.mock('./rate-limit', () => ({
   rateLimitGuard: rateLimitGuardMock,
   noteRateLimitSpend: vi.fn(),
diff --git a/src/main/github/client-pr-local-runtime.test.ts b/src/main/github/client-pr-local-runtime.test.ts
index c5e28ce0fed..d54db52aaa1 100644
--- a/src/main/github/client-pr-local-runtime.test.ts
+++ b/src/main/github/client-pr-local-runtime.test.ts
@@ -442,6 +442,9 @@ describe('GitHub PR local runtime routing', () => {
     await expect(
       getWorkItemByOwnerRepo('/remote/repo', enterpriseRepo, 7, 'pr', 'ssh-1')
     ).resolves.toMatchObject({ number: 7, title: 'Enterprise PR' })
+    await expect(
+      getWorkItemByOwnerRepo('/remote/repo', { owner: 'team', repo: 'orca' }, 7, 'pr', 'ssh-1')
+    ).resolves.toMatchObject({ number: 7, title: 'Enterprise PR' })
     await expect(
       getPRComments('/remote/repo', 7, { prRepo: enterpriseRepo }, 'ssh-1')
     ).resolves.toEqual([])
diff --git a/src/main/github/client.ts b/src/main/github/client.ts
index 01b460d3ee0..0bd5e56ae19 100644
--- a/src/main/github/client.ts
+++ b/src/main/github/client.ts
@@ -81,6 +81,7 @@ import {
   githubHostExecOptions,
   githubRepositorySlugArg,
   githubRepositoryWebHost,
+  resolveGitHubApiRepository,
   resolveGitHubApiRepositoryCandidates,
   resolveGitHubRepoExecution,
   resolveIssueGitHubApiRepositorySource,
@@ -2156,12 +2157,19 @@ export async function getWorkItemByOwnerRepo(
   connectionId?: string | null,
   localGitOptions: LocalGitExecOptions = {}
 ): Promise<MainWorkItem | null> {
+  const requestedHost = ownerRepo.host?.trim().toLowerCase()
+  const requestedRepository = requestedHost
+    ? { ...ownerRepo, host: requestedHost }
+    : await resolveGitHubApiRepository(repoPath, ownerRepo, connectionId, localGitOptions)
+  if (!requestedRepository) {
+    return null
+  }
   const { candidates } = await resolveGitHubApiRepositoryCandidates(
     repoPath,
     connectionId,
     localGitOptions
   )
-  const requestedKey = githubRepoIdentityKey(ownerRepo)
+  const requestedKey = githubRepoIdentityKey(requestedRepository)
   const matchedRepository = candidates.find(
     (candidate) => githubRepoIdentityKey(candidate) === requestedKey
   )
diff --git a/src/main/github/github-api-repository.test.ts b/src/main/github/github-api-repository.test.ts
index 64ff0f8ead1..e3fd4666c7d 100644
--- a/src/main/github/github-api-repository.test.ts
+++ b/src/main/github/github-api-repository.test.ts
@@ -1,22 +1,36 @@
 import { beforeEach, describe, expect, it, vi } from 'vitest'
 import type * as GitHubEnterpriseRepository from './github-enterprise-repository'
+import type * as GhUtils from './gh-utils'
 
-const { isGitHubHostAuthenticatedMock } = vi.hoisted(() => ({
-  isGitHubHostAuthenticatedMock: vi.fn()
+const { getEnterpriseGitHubRepoSlugMock, getOwnerRepoMock, isGitHubHostAuthenticatedMock } =
+  vi.hoisted(() => ({
+    getEnterpriseGitHubRepoSlugMock: vi.fn(),
+    getOwnerRepoMock: vi.fn(),
+    isGitHubHostAuthenticatedMock: vi.fn()
+  }))
+
+vi.mock('./gh-utils', async (importOriginal) => ({
+  ...(await importOriginal<typeof GhUtils>()),
+  getOwnerRepo: getOwnerRepoMock
 }))
 
 vi.mock('./github-enterprise-repository', async (importOriginal) => ({
   ...(await importOriginal<typeof GitHubEnterpriseRepository>()),
+  getEnterpriseGitHubRepoSlug: getEnterpriseGitHubRepoSlugMock,
   isGitHubHostAuthenticated: isGitHubHostAuthenticatedMock
 }))
 
 import {
+  _resetOriginGitHubApiRepositoryCache,
   githubHostExecOptions,
   resolveGitHubApiRepository,
   resolveGitHubRepoExecution
 } from './github-api-repository'
 
 beforeEach(() => {
+  _resetOriginGitHubApiRepositoryCache()
+  getEnterpriseGitHubRepoSlugMock.mockReset().mockResolvedValue(null)
+  getOwnerRepoMock.mockReset().mockResolvedValue(null)
   isGitHubHostAuthenticatedMock.mockReset().mockResolvedValue(false)
 })
 
@@ -80,6 +94,20 @@ describe('resolveGitHubRepoExecution', () => {
     )
   })
 
+  it.each([
+    { owner: 'acme%2Fadmin', repo: 'widgets' },
+    { owner: 'acme', repo: '..' }
+  ])('rejects repository overrides that could alter a gh REST path: %o', async (repository) => {
+    await expect(
+      resolveGitHubApiRepository('/repo', {
+        ...repository,
+        host: 'github.com'
+      })
+    ).resolves.toBeNull()
+
+    expect(isGitHubHostAuthenticatedMock).not.toHaveBeenCalled()
+  })
+
   it('normalizes github.com without spending an auth inventory probe', async () => {
     await expect(
       resolveGitHubApiRepository('/repo', {
@@ -92,14 +120,48 @@ describe('resolveGitHubRepoExecution', () => {
     expect(isGitHubHostAuthenticatedMock).not.toHaveBeenCalled()
   })
 
-  it('uses a caller-specific repository resolver without changing its identity', async () => {
+  it('backfills the origin host for a host-less caller-specific resolver', async () => {
     const ownerRepo = { owner: 'upstream', repo: 'widgets' }
+    getOwnerRepoMock.mockResolvedValue({ owner: 'fork', repo: 'widgets' })
 
-    await expect(
-      resolveGitHubRepoExecution('/remote/repo', async () => ownerRepo, 'ssh-1')
-    ).resolves.toEqual({
-      ownerRepo,
-      ghOptions: {}
+    await expect(resolveGitHubRepoExecution('/repo', async () => ownerRepo)).resolves.toEqual({
+      ownerRepo: { ...ownerRepo, host: 'github.com' },
+      ghOptions: { cwd: '/repo', host: 'github.com' }
     })
   })
+
+  it('backfills an Enterprise origin host for a host-less caller-specific resolver', async () => {
+    const ownerRepo = { owner: 'upstream', repo: 'widgets' }
+    getEnterpriseGitHubRepoSlugMock.mockResolvedValue({
+      owner: 'fork',
+      repo: 'widgets',
+      host: 'github.acme-corp.com'
+    })
+
+    await expect(resolveGitHubRepoExecution('/repo', async () => ownerRepo)).resolves.toEqual({
+      ownerRepo: { ...ownerRepo, host: 'github.acme-corp.com' },
+      ghOptions: { cwd: '/repo', host: 'github.acme-corp.com' }
+    })
+  })
+
+  it('rejects a host-less caller-specific resolver for a connection-backed repository', async () => {
+    await expect(
+      resolveGitHubRepoExecution(
+        '/remote/repo',
+        async () => ({ owner: 'upstream', repo: 'widgets' }),
+        'ssh-1'
+      )
+    ).resolves.toEqual({ ownerRepo: null, ghOptions: {} })
+  })
+
+  it('preserves an authoritative null from a caller-specific resolver', async () => {
+    getOwnerRepoMock.mockResolvedValue({ owner: 'origin', repo: 'widgets' })
+
+    await expect(resolveGitHubRepoExecution('/repo', async () => null)).resolves.toEqual({
+      ownerRepo: null,
+      ghOptions: { cwd: '/repo' }
+    })
+
+    expect(getOwnerRepoMock).not.toHaveBeenCalled()
+  })
 })
diff --git a/src/main/github/github-api-repository.ts b/src/main/github/github-api-repository.ts
index ce342b74f25..1ca1ec9c155 100644
--- a/src/main/github/github-api-repository.ts
+++ b/src/main/github/github-api-repository.ts
@@ -29,6 +29,20 @@ type GitHubApiRepositoryResolution =
   | undefined
   | (() => Promise<GitHubApiRepository | null>)
 
+// Why: renderer/RPC repository overrides are interpolated into REST paths.
+// Reject path syntax before an authenticated gh process can target it.
+const GITHUB_OWNER_SLUG_RE = /^[A-Za-z0-9][A-Za-z0-9-]*$/
+const GITHUB_REPO_SLUG_RE = /^[A-Za-z0-9._-]+$/
+
+function isValidGitHubApiRepository(repository: GitHubApiRepository): boolean {
+  return (
+    GITHUB_OWNER_SLUG_RE.test(repository.owner) &&
+    GITHUB_REPO_SLUG_RE.test(repository.repo) &&
+    repository.repo !== '.' &&
+    repository.repo !== '..'
+  )
+}
+
 // Why: the enterprise branch spawns an uncached `git remote get-url` (an SSH
 // round trip on connection-backed repos) — hot paths like per-file contents
 // and viewed-state toggles resolve per call, so cache like ownerRepoCache does.
@@ -240,6 +254,9 @@ export async function resolveGitHubApiRepository(
   connectionId?: string | null,
   localGitOptions: LocalGitExecOptions = {}
 ): Promise<GitHubApiRepository | null> {
+  if (repository && !isValidGitHubApiRepository(repository)) {
+    return null
+  }
   if (repository?.host) {
     const host = repository.host.trim().toLowerCase()
     if (!host) {
@@ -297,10 +314,18 @@ export async function resolveGitHubRepoExecution(
 ): Promise<GitHubRepoExecution> {
   // Why: issue-scoped paths retain their upstream-first resolver while sharing
   // the same repo-scoped and host-scoped gh execution option construction.
+  const requestedRepository = typeof repository === 'function' ? await repository() : repository
+  // Why: normalize host-less resolver results without replacing an
+  // authoritative null with the generic origin fallback.
   const ownerRepo =
-    typeof repository === 'function'
-      ? await repository()
-      : await resolveGitHubApiRepository(repoPath, repository, connectionId, localGitOptions)
+    typeof repository === 'function' && !requestedRepository
+      ? null
+      : await resolveGitHubApiRepository(
+          repoPath,
+          requestedRepository,
+          connectionId,
+          localGitOptions
+        )
   return {
     ownerRepo,
     ghOptions: {
diff --git a/src/main/github/issues.test.ts b/src/main/github/issues.test.ts
index e510a363cb1..90b090b347a 100644
--- a/src/main/github/issues.test.ts
+++ b/src/main/github/issues.test.ts
@@ -1,5 +1,6 @@
 import { beforeEach, describe, expect, it, vi } from 'vitest'
 import type * as GithubApiRepositoryModule from './github-api-repository'
+import type * as GithubEnterpriseRepositoryModule from './github-enterprise-repository'
 import type * as GhUtils from './gh-utils'
 
 const {
@@ -28,6 +29,11 @@ vi.mock('./gh-utils', async () => {
   }
 })
 
+vi.mock('./github-enterprise-repository', async (importOriginal) => ({
+  ...(await importOriginal<typeof GithubEnterpriseRepositoryModule>()),
+  isGitHubHostAuthenticated: vi.fn().mockResolvedValue(true)
+}))
+
 vi.mock('./github-api-repository', async (importOriginal) => {
   const actual = await importOriginal<typeof GithubApiRepositoryModule>()
   return {
diff --git a/src/main/github/project-view-host-auth.test.ts b/src/main/github/project-view-host-auth.test.ts
index ec426d95319..f243c06ed45 100644
--- a/src/main/github/project-view-host-auth.test.ts
+++ b/src/main/github/project-view-host-auth.test.ts
@@ -36,6 +36,7 @@ vi.mock('./github-enterprise-repository', () => ({
 }))
 
 import { runGraphql, runRest } from './project-view/internals'
+import { _resetProjectViewCachesForTests, resolveProjectRef } from './project-view'
 
 describe('project view host authentication boundary', () => {
   beforeEach(() => {
@@ -44,6 +45,7 @@ describe('project view host authentication boundary', () => {
     ghExecFileAsyncMock.mockReset()
     hostAuthenticatedMock.mockReset()
     noteRepositoryRateLimitSpendMock.mockReset()
+    _resetProjectViewCachesForTests()
   })
 
   it('does not send GraphQL or REST requests to an unconfigured host', async () => {
@@ -90,4 +92,34 @@ describe('project view host authentication boundary', () => {
 
     expect(hostAuthenticatedMock).not.toHaveBeenCalled()
   })
+
+  it('uses a pasted github.com URL instead of the ambient Enterprise host', async () => {
+    ghExecFileAsyncMock.mockImplementation(async (args: string[]) => {
+      const query = args.find((arg) => arg.startsWith('query=')) ?? ''
+      return query.includes('projectV2')
+        ? {
+            stdout: JSON.stringify({
+              data: { organization: { projectV2: { id: 'PVT_7', title: 'Roadmap' } } }
+            }),
+            stderr: ''
+          }
+        : {
+            stdout: JSON.stringify({ data: { organization: { login: 'acme' } } }),
+            stderr: ''
+          }
+    })
+
+    await expect(
+      resolveProjectRef({
+        input: 'https://github.com/orgs/acme/projects/7',
+        host: 'github.corp.example'
+      })
+    ).resolves.toMatchObject({ ok: true, host: 'github.com' })
+
+    expect(ghExecFileAsyncMock).toHaveBeenCalledTimes(2)
+    expect(
+      ghExecFileAsyncMock.mock.calls.every(([, options]) => options.host === 'github.com')
+    ).toBe(true)
+    expect(hostAuthenticatedMock).not.toHaveBeenCalled()
+  })
 })
diff --git a/src/main/github/project-view.test.ts b/src/main/github/project-view.test.ts
index 0c1a7472887..f5f468b7d9b 100644
--- a/src/main/github/project-view.test.ts
+++ b/src/main/github/project-view.test.ts
@@ -136,6 +136,7 @@ describe('parseProjectPaste', () => {
       kind: 'org',
       owner: 'acme',
       number: 42,
+      host: 'github.com',
       viewNumber: 3
     })
   })
@@ -144,7 +145,8 @@ describe('parseProjectPaste', () => {
     expect(parseProjectPaste('https://github.com/users/octocat/projects/1')).toEqual({
       kind: 'user',
       owner: 'octocat',
-      number: 1
+      number: 1,
+      host: 'github.com'
     })
   })
 
@@ -158,13 +160,14 @@ describe('parseProjectPaste', () => {
       kind: 'org',
       owner: 'acme',
       number: 7,
+      host: 'github.corp.example',
       viewNumber: 2
     })
     expect(parseProjectPaste(url)).toBeNull()
     // github.com URLs still parse when a GHES host is supplied.
     expect(
       parseProjectPaste('https://github.com/orgs/acme/projects/7', 'github.corp.example')
-    ).toEqual({ kind: 'org', owner: 'acme', number: 7 })
+    ).toEqual({ kind: 'org', owner: 'acme', number: 7, host: 'github.com' })
   })
 
   it('preserves a GHES custom port while parsing project URLs', () => {
@@ -173,7 +176,12 @@ describe('parseProjectPaste', () => {
         'https://github.corp.example:8443/orgs/acme/projects/7',
         'github.corp.example:8443'
       )
-    ).toEqual({ kind: 'org', owner: 'acme', number: 7 })
+    ).toEqual({
+      kind: 'org',
+      owner: 'acme',
+      number: 7,
+      host: 'github.corp.example:8443'
+    })
   })
 
   it('rejects credentials and paths that only begin like a Project URL', () => {
diff --git a/src/main/github/project-view.ts b/src/main/github/project-view.ts
index 2cd220c2b5d..d0a47b9a8aa 100644
--- a/src/main/github/project-view.ts
+++ b/src/main/github/project-view.ts
@@ -1612,8 +1612,8 @@ export async function listAccessibleProjects(
 // ─── resolveProjectRef ─────────────────────────────────────────────────
 
 type ParsedPaste =
-  | { kind: 'org'; owner: string; number: number; viewNumber?: number }
-  | { kind: 'user'; owner: string; number: number; viewNumber?: number }
+  | { kind: 'org'; owner: string; number: number; host: string; viewNumber?: number }
+  | { kind: 'user'; owner: string; number: number; host: string; viewNumber?: number }
   | { kind: 'bare'; owner: string; number: number }
 
 export function parseProjectPaste(input: string, host?: string): ParsedPaste | null {
@@ -1656,6 +1656,7 @@ export function parseProjectPaste(input: string, host?: string): ParsedPaste | n
       kind: parts[0] === 'orgs' ? 'org' : 'user',
       owner: parts[1],
       number,
+      host: url.host.toLowerCase(),
       ...(viewNumber !== undefined ? { viewNumber } : {})
     }
   } catch {
@@ -1785,8 +1786,11 @@ export async function resolveProjectRef(
   }
   const preferred: GitHubProjectOwnerType | null =
     parsed.kind === 'org' ? 'organization' : parsed.kind === 'user' ? 'user' : null
+  // Why: a pasted URL is authoritative. The ambient host only applies to
+  // owner/number shorthand; otherwise same-number Projects can cross hosts.
+  const executionHost = parsed.kind === 'bare' ? githubProjectHost(args.host) : parsed.host
   // Verify by fetching project title.
-  const ownerRes = await resolveOwnerType(parsed.owner, preferred, args.host)
+  const ownerRes = await resolveOwnerType(parsed.owner, preferred, executionHost)
   if (!ownerRes.ok) {
     return { ok: false, error: ownerRes.error }
   }
@@ -1799,7 +1803,7 @@ export async function resolveProjectRef(
   `
   const res = await runGraphql<
     Record<string, { projectV2?: { id?: string; title?: string } | null } | null>
-  >(query, { owner: parsed.owner, num: parsed.number }, projectGhExecOptions(args.host))
+  >(query, { owner: parsed.owner, num: parsed.number }, projectGhExecOptions(executionHost))
   if (!res.ok) {
     return { ok: false, error: res.error }
   }
@@ -1813,7 +1817,7 @@ export async function resolveProjectRef(
     ownerType,
     number: parsed.number,
     title: p.title ?? '',
-    host: githubProjectHost(args.host),
+    host: executionHost,
     // Why: forward the parsed view number from /views/{n} URLs so the
     // renderer can skip the view-pick step. parsed.kind === 'bare' has no
     // viewNumber (owner/number shorthand carries no view).
diff --git a/src/main/github/work-item-details-pr-files.test.ts b/src/main/github/work-item-details-pr-files.test.ts
index fc86f204c8e..93c524ae888 100644
--- a/src/main/github/work-item-details-pr-files.test.ts
+++ b/src/main/github/work-item-details-pr-files.test.ts
@@ -1,5 +1,9 @@
 import { beforeEach, describe, expect, it, vi } from 'vitest'
 
+type RateLimitGuardResult =
+  | { blocked: false }
+  | { blocked: true; remaining: number; limit: number; resetAt: number }
+
 const {
   ghExecFileAsyncMock,
   getOwnerRepoMock,
@@ -28,7 +32,7 @@ const {
       repository: { host?: string } | null | undefined,
       bucket: string,
       options?: { cwd?: string; host?: string }
-    ) => { blocked: false }
+    ) => RateLimitGuardResult
   >(() => ({ blocked: false }))
 }))
 
@@ -65,7 +69,7 @@ vi.mock('./rate-limit', () => ({
   noteRepositoryRateLimitSpend: noteRepositoryRateLimitSpendMock
 }))
 
-import { getWorkItemDetails } from './work-item-details'
+import { getPRFileContents, getWorkItemDetails } from './work-item-details'
 
 import { _resetOriginGitHubApiRepositoryCache } from './github-api-repository'
 
@@ -126,7 +130,8 @@ describe('getWorkItemDetails PR file listing', () => {
     getPRCommentsMock.mockReset()
     getPRCommentsMock.mockResolvedValue([])
     noteRepositoryRateLimitSpendMock.mockReset()
-    repositoryRateLimitGuardMock.mockClear()
+    repositoryRateLimitGuardMock.mockReset()
+    repositoryRateLimitGuardMock.mockReturnValue({ blocked: false })
   })
 
   it('loads files beyond the first 100-result REST page', async () => {
@@ -217,4 +222,77 @@ describe('getWorkItemDetails PR file listing', () => {
     expect(details?.filesUnavailable).toBe(false)
     expect(details?.files).toEqual([])
   })
+
+  it('uses the selected upstream GitHub Enterprise repo for both PR file sides', async () => {
+    const prRepo = {
+      owner: 'team',
+      repo: 'orca',
+      host: 'github.acme-corp.com'
+    }
+    ghExecFileAsyncMock.mockImplementation(async (args: string[]) => {
+      const endpoint = args.find((arg) => arg.startsWith('repos/')) ?? ''
+      if (endpoint === 'repos/team/orca/contents/src/path%23with%3Fchars.ts?ref=base-sha') {
+        return { stdout: 'base content' }
+      }
+      if (endpoint === 'repos/team/orca/contents/src/path%23with%3Fchars.ts?ref=head-sha') {
+        return { stdout: 'head content' }
+      }
+      throw new Error(`unexpected gh call: ${args.join(' ')}`)
+    })
+
+    const contents = await getPRFileContents({
+      repoPath: '/repo-root',
+      prRepo,
+      prNumber: 7,
+      path: 'src/path#with?chars.ts',
+      status: 'modified',
+      headSha: 'head-sha',
+      baseSha: 'base-sha'
+    })
+
+    expect(contents).toMatchObject({
+      original: 'base content',
+      modified: 'head content',
+      originalIsBinary: false,
+      modifiedIsBinary: false
+    })
+    const apiCalls = ghExecFileAsyncMock.mock.calls.map(([args]) => args as string[])
+    expect(apiCalls).toHaveLength(2)
+    expect(apiCalls.every((args) => !args.includes('--hostname'))).toBe(true)
+    expect(
+      ghExecFileAsyncMock.mock.calls.every(
+        ([, options]) => options?.host === 'github.acme-corp.com'
+      )
+    ).toBe(true)
+    expect(
+      repositoryRateLimitGuardMock.mock.calls.filter(([, bucket]) => bucket === 'core')
+    ).toHaveLength(2)
+    expect(
+      noteRepositoryRateLimitSpendMock.mock.calls.filter(([, bucket]) => bucket === 'core')
+    ).toHaveLength(2)
+  })
+
+  it('does not fetch raw PR file contents while the repository core budget is blocked', async () => {
+    repositoryRateLimitGuardMock.mockReturnValue({
+      blocked: true,
+      remaining: 0,
+      limit: 5000,
+      resetAt: 1_800_000_000
+    })
+
+    await expect(
+      getPRFileContents({
+        repoPath: '/repo-root',
+        prRepo: { owner: 'team', repo: 'orca', host: 'github.acme-corp.com' },
+        prNumber: 7,
+        path: 'src/file.ts',
+        status: 'modified',
+        headSha: 'head-sha',
+        baseSha: 'base-sha'
+      })
+    ).resolves.toMatchObject({ original: '', modified: '' })
+
+    expect(ghExecFileAsyncMock).not.toHaveBeenCalled()
+    expect(noteRepositoryRateLimitSpendMock).not.toHaveBeenCalled()
+  })
 })
diff --git a/src/main/github/work-item-details.test.ts b/src/main/github/work-item-details.test.ts
index cf9f2b86fef..5d939eda1f2 100644
--- a/src/main/github/work-item-details.test.ts
+++ b/src/main/github/work-item-details.test.ts
@@ -30,7 +30,13 @@ const {
   getWorkItemByOwnerRepoMock: vi.fn(),
   getPRChecksMock: vi.fn(),
   getPRCommentsMock: vi.fn(),
-  repositoryRateLimitGuardMock: vi.fn<() => RateLimitGuardResult>(() => ({ blocked: false })),
+  repositoryRateLimitGuardMock: vi.fn<
+    (
+      repository: { host?: string } | null | undefined,
+      bucket: 'core' | 'graphql' | 'search',
+      options?: { cwd?: string; wslDistro?: string }
+    ) => RateLimitGuardResult
+  >(() => ({ blocked: false })),
   noteRepositoryRateLimitSpendMock: vi.fn(),
   ghRepoExecOptionsMock: vi.fn((context) =>
     context.connectionId
@@ -74,7 +80,7 @@ vi.mock('./rate-limit', () => ({
   noteRepositoryRateLimitSpend: noteRepositoryRateLimitSpendMock
 }))
 
-import { getPRFileContents, getWorkItemDetails } from './work-item-details'
+import { getWorkItemDetails } from './work-item-details'
 
 import { _resetOriginGitHubApiRepositoryCache } from './github-api-repository'
 
@@ -252,6 +258,17 @@ describe('getWorkItemDetails', () => {
       1,
       { cwd: '/repo-root', host: 'github.com' }
     )
+    expect(repositoryRateLimitGuardMock).toHaveBeenCalledWith(
+      { owner: 'acme', repo: 'widgets', host: 'github.com' },
+      'core',
+      { cwd: '/repo-root', host: 'github.com' }
+    )
+    expect(noteRepositoryRateLimitSpendMock).toHaveBeenCalledWith(
+      { owner: 'acme', repo: 'widgets', host: 'github.com' },
+      'core',
+      1,
+      { cwd: '/repo-root', host: 'github.com' }
+    )
   })
 
   it('scopes collapsed issue GraphQL accounting to an implicit WSL UNC runtime', async () => {
@@ -486,12 +503,16 @@ describe('getWorkItemDetails', () => {
   })
 
   it('skips optional GraphQL issue detail calls when the cached GraphQL budget is low', async () => {
-    repositoryRateLimitGuardMock.mockReturnValue({
-      blocked: true,
-      remaining: 3,
-      limit: 5000,
-      resetAt: 1_800_000_000
-    })
+    repositoryRateLimitGuardMock.mockImplementation((_repository, bucket) =>
+      bucket === 'graphql'
+        ? {
+            blocked: true,
+            remaining: 3,
+            limit: 5000,
+            resetAt: 1_800_000_000
+          }
+        : { blocked: false }
+    )
     getWorkItemMock.mockResolvedValueOnce({
       id: 'issue:923',
       type: 'issue',
@@ -513,7 +534,15 @@ describe('getWorkItemDetails', () => {
 
     expect(ghExecFileAsyncMock).toHaveBeenCalledTimes(3)
     expect(ghExecFileAsyncMock.mock.calls.some((call) => call[0][1] === 'graphql')).toBe(false)
-    expect(noteRepositoryRateLimitSpendMock).not.toHaveBeenCalled()
+    expect(
+      noteRepositoryRateLimitSpendMock.mock.calls.some(([, bucket]) => bucket === 'graphql')
+    ).toBe(false)
+    expect(noteRepositoryRateLimitSpendMock).toHaveBeenCalledWith(
+      { owner: 'acme', repo: 'widgets', host: 'github.com' },
+      'core',
+      2,
+      { cwd: '/repo-root', host: 'github.com' }
+    )
     expect(details?.body).toBe('Issue body')
     expect(details?.participants).toEqual([])
   })
@@ -847,50 +876,6 @@ describe('getWorkItemDetails', () => {
     expect(ghExecFileAsyncMock).not.toHaveBeenCalled()
   })
 
-  it('uses the selected upstream GitHub Enterprise repo for both PR file sides', async () => {
-    getOwnerRepoMock.mockResolvedValue({ owner: 'fork', repo: 'orca' })
-    const prRepo = {
-      owner: 'team',
-      repo: 'orca',
-      host: 'github.acme-corp.com'
-    }
-    ghExecFileAsyncMock.mockImplementation(async (args: string[]) => {
-      const endpoint = args.find((arg) => arg.startsWith('repos/')) ?? ''
-      if (endpoint === 'repos/team/orca/contents/src/path%23with%3Fchars.ts?ref=base-sha') {
-        return { stdout: 'base content' }
-      }
-      if (endpoint === 'repos/team/orca/contents/src/path%23with%3Fchars.ts?ref=head-sha') {
-        return { stdout: 'head content' }
-      }
-      throw new Error(`unexpected gh call: ${args.join(' ')}`)
-    })
-
-    const contents = await getPRFileContents({
-      repoPath: '/repo-root',
-      prRepo,
-      prNumber: 7,
-      path: 'src/path#with?chars.ts',
-      status: 'modified',
-      headSha: 'head-sha',
-      baseSha: 'base-sha'
-    })
-
-    expect(contents).toMatchObject({
-      original: 'base content',
-      modified: 'head content',
-      originalIsBinary: false,
-      modifiedIsBinary: false
-    })
-    const apiCalls = ghExecFileAsyncMock.mock.calls.map(([args]) => args as string[])
-    expect(apiCalls).toHaveLength(2)
-    expect(apiCalls.every((args) => !args.includes('--hostname'))).toBe(true)
-    expect(
-      ghExecFileAsyncMock.mock.calls.every(
-        ([, options]) => options?.host === 'github.acme-corp.com'
-      )
-    ).toBe(true)
-  })
-
   // Why: a rate-limited/auth-failed file fetch must not render as an empty PR;
   // the Files tab keys its retry state off details.filesUnavailable.
   it('flags filesUnavailable when the PR file fetch fails but leaves the PR empty otherwise intact', async () => {
diff --git a/src/main/github/work-item-details.ts b/src/main/github/work-item-details.ts
index 94df5d33123..c5cc9f5a479 100644
--- a/src/main/github/work-item-details.ts
+++ b/src/main/github/work-item-details.ts
@@ -296,6 +296,10 @@ async function getIssueTimelineItems(
   try {
     const items: GitHubIssueTimelineItem[] = []
     for (let page = 1; items.length < MAX_ISSUE_TIMELINE_ITEMS; page += 1) {
+      if (repositoryRateLimitGuard(ownerRepo, 'core', ghOptions).blocked) {
+        return items
+      }
+      noteRepositoryRateLimitSpend(ownerRepo, 'core', 1, ghOptions)
       const { stdout } = await ghExecFileAsync(
         [
           'api',
@@ -728,6 +732,12 @@ async function getIssueBodyAndComments(
   }
   try {
     if (ownerRepo) {
+      if (repositoryRateLimitGuard(ownerRepo, 'core', ghOptions).blocked) {
+        return { body: '', comments: [], assignees: [], timelineItems: [] }
+      }
+      // Why: the fallback starts the issue and comments reads together; debit
+      // both before spawning so a failed response cannot leave quota overstated.
+      noteRepositoryRateLimitSpend(ownerRepo, 'core', 2, ghOptions)
       const [issueResult, commentsResult, timelineItems] = await Promise.all([
         ghExecFileAsync(
           [
@@ -1258,7 +1268,16 @@ async function fetchContentAtRef(args: {
   path: string
   ref: string
 }): Promise<{ content: string; isBinary: boolean; tooLarge?: boolean }> {
+  const ghOptions = {
+    ...ghRepoExecOptions(githubRepoContext(args.repoPath, args.connectionId, args.localGitOptions)),
+    ...githubHostExecOptions(args.ownerRepo),
+    maxBuffer: GITHUB_RAW_CONTENT_MAX_BUFFER_BYTES
+  }
+  if (repositoryRateLimitGuard(args.ownerRepo, 'core', ghOptions).blocked) {
+    return { content: '', isBinary: false }
+  }
   try {
+    noteRepositoryRateLimitSpend(args.ownerRepo, 'core', 1, ghOptions)
     const { stdout } = await ghExecFileAsync(
       [
         'api',
@@ -1268,13 +1287,7 @@ async function fetchContentAtRef(args: {
         'Accept: application/vnd.github.raw',
         `repos/${args.ownerRepo.owner}/${args.ownerRepo.repo}/contents/${encodeGitHubContentPath(args.path)}?ref=${encodeURIComponent(args.ref)}`
       ],
-      {
-        ...ghRepoExecOptions(
-          githubRepoContext(args.repoPath, args.connectionId, args.localGitOptions)
-        ),
-        ...githubHostExecOptions(args.ownerRepo),
-        maxBuffer: GITHUB_RAW_CONTENT_MAX_BUFFER_BYTES
-      }
+      ghOptions
     )
     // Raw content response: Electron's execFile returns string in utf-8. If the
     // file is binary, the string will contain replacement characters — we treat
diff --git a/src/renderer/src/components/github-item-dialog-source-boundary.test.ts b/src/renderer/src/components/github-item-dialog-source-boundary.test.ts
index 6851fdb3a2a..f8b83e2d453 100644
--- a/src/renderer/src/components/github-item-dialog-source-boundary.test.ts
+++ b/src/renderer/src/components/github-item-dialog-source-boundary.test.ts
@@ -41,7 +41,7 @@ describe('GitHubItemDialog source host boundaries', () => {
     )
     expect(section).toContain("'github.requestPRReviewers'")
     expect(section).toContain("'github.removePRReviewers'")
-    expect(section).toContain('{ repo: runtimeRepo, prNumber: item.number, reviewers: logins }')
+    expect(section.match(/prRepo: item\.prRepo \?\? reviewSlug/g)).toHaveLength(4)
     expect(section).toContain('notifyWorkItemDetailsMutation(')
     expect(section).toContain('{ local: false }')
   })
diff --git a/src/renderer/src/components/github-project/ProjectPicker.tsx b/src/renderer/src/components/github-project/ProjectPicker.tsx
index b1dd25f0f28..8322a5d8134 100644
--- a/src/renderer/src/components/github-project/ProjectPicker.tsx
+++ b/src/renderer/src/components/github-project/ProjectPicker.tsx
@@ -3,7 +3,7 @@
 // header tab strip). Pinned + Recent come from settings; Browse all lazy-loads
 // from `listAccessibleProjects` and is cached for 5 minutes. Paste-to-add
 // accepts org/user project URLs and `owner/number` shorthand.
-import React, { useCallback, useEffect, useMemo, useState } from 'react'
+import React, { useCallback, useEffect, useMemo, useRef, useState } from 'react'
 import { AlertTriangle, ChevronDown, Loader, Pin, Search } from 'lucide-react'
 import { toast } from 'sonner'
 import { GhAuthErrorHelp } from '@/components/github-project/GhAuthErrorHelp'
@@ -61,17 +61,20 @@ type Props = {
 }
 
 function getProjectPickerRuntimeScope(
-  settings: Parameters<typeof getActiveRuntimeTarget>[0]
+  settings: Parameters<typeof getActiveRuntimeTarget>[0],
+  host: string
 ): string {
   const target = getActiveRuntimeTarget(settings)
-  return target.kind === 'environment' ? `runtime:${target.environmentId}` : 'local'
+  const runtimeScope = target.kind === 'environment' ? `runtime:${target.environmentId}` : 'local'
+  return `${runtimeScope}\0${host.toLowerCase()}`
 }
 
 async function listAccessibleProjectsForRuntime(
-  settings: Parameters<typeof getActiveRuntimeTarget>[0]
+  settings: Parameters<typeof getActiveRuntimeTarget>[0],
+  host: string
 ): Promise<ListAccessibleProjectsResult> {
   const target = getActiveRuntimeTarget(settings)
-  const args = { host: 'github.com' }
+  const args = { host }
   return target.kind === 'environment'
     ? callRuntimeRpc<ListAccessibleProjectsResult>(target, 'github.project.listAccessible', args, {
         timeoutMs: 60_000
@@ -79,6 +82,10 @@ async function listAccessibleProjectsForRuntime(
     : window.api.gh.listAccessibleProjects(args)
 }
 
+export function getProjectPickerBrowseHost(activeProject: { host?: string } | null): string {
+  return githubProjectHost(activeProject?.host).toLowerCase()
+}
+
 async function listProjectViewsForRuntime(
   settings: Parameters<typeof getActiveRuntimeTarget>[0],
   args: {
@@ -131,7 +138,11 @@ export default function ProjectPicker({ activeProject, onSelect }: Props): React
   const [query, setQuery] = useState('')
   const [browseLoading, setBrowseLoading] = useState(false)
   const [browseError, setBrowseError] = useState<GitHubProjectViewError | null>(null)
-  const browseCache = peekProjectPickerBrowseCacheEntry(getProjectPickerRuntimeScope(settings))
+  const browseHost = getProjectPickerBrowseHost(activeProject ?? projectSettings.activeProject)
+  const browseCacheKey = getProjectPickerRuntimeScope(settings, browseHost)
+  const activeBrowseCacheKeyRef = useRef(browseCacheKey)
+  activeBrowseCacheKeyRef.current = browseCacheKey
+  const browseCache = peekProjectPickerBrowseCacheEntry(browseCacheKey)
   const [browseProjects, setBrowseProjects] = useState<GitHubProjectSummary[]>(
     () => browseCache?.projects ?? []
   )
@@ -152,46 +163,52 @@ export default function ProjectPicker({ activeProject, onSelect }: Props): React
   const [viewLoading, setViewLoading] = useState(false)
 
   const loadBrowse = useCallback(async () => {
-    const cacheKey = getProjectPickerRuntimeScope(settings)
+    const cacheKey = browseCacheKey
     const cached = getProjectPickerBrowseCacheEntry(cacheKey)
     if (cached) {
+      setBrowseLoading(false)
+      setBrowseError(null)
       setBrowseProjects(cached.projects)
       setPartialFailures(cached.partialFailures ?? [])
       return
     }
     setBrowseLoading(true)
     setBrowseError(null)
+    setBrowseProjects([])
+    setPartialFailures([])
     try {
-      const res = await listAccessibleProjectsForRuntime(settings)
+      const res = await listAccessibleProjectsForRuntime(settings, browseHost)
       if (res.ok) {
         rememberProjectPickerBrowseCacheEntry(cacheKey, {
           projects: res.projects,
           partialFailures: res.partialFailures
         })
-        if (!mountedRef.current) {
+        // Why: runtime or active-host changes can leave the prior request in
+        // flight; its scoped cache is useful, but its rows must not cross hosts.
+        if (!mountedRef.current || activeBrowseCacheKeyRef.current !== cacheKey) {
           return
         }
         setBrowseProjects(res.projects)
         setPartialFailures(res.partialFailures ?? [])
       } else {
-        if (!mountedRef.current) {
+        if (!mountedRef.current || activeBrowseCacheKeyRef.current !== cacheKey) {
           return
         }
         setBrowseError(res.error)
       }
     } catch (err) {
-      if (mountedRef.current) {
+      if (mountedRef.current && activeBrowseCacheKeyRef.current === cacheKey) {
         setBrowseError({
           type: 'unknown',
           message: err instanceof Error ? err.message : 'Failed to list projects'
         })
       }
     } finally {
-      if (mountedRef.current) {
+      if (mountedRef.current && activeBrowseCacheKeyRef.current === cacheKey) {
         setBrowseLoading(false)
       }
     }
-  }, [mountedRef, settings])
+  }, [browseCacheKey, browseHost, mountedRef, settings])
 
   useEffect(() => {
     if (open && !viewPickFor) {
@@ -449,7 +466,7 @@ export default function ProjectPicker({ activeProject, onSelect }: Props): React
                 />
               </div>
             </div>
-            {browseError ? <AuthErrorBanner error={browseError} /> : null}
+            {browseError ? <AuthErrorBanner error={browseError} host={browseHost} /> : null}
             {!browseError && partialFailures.length > 0 ? (
               <PartialFailuresBanner failures={partialFailures} />
             ) : null}
@@ -808,13 +825,19 @@ function PartialFailuresBanner({
   )
 }
 
-function AuthErrorBanner({ error }: { error: GitHubProjectViewError }): React.JSX.Element {
+function AuthErrorBanner({
+  error,
+  host
+}: {
+  error: GitHubProjectViewError
+  host: string
+}): React.JSX.Element {
   if (error.type === 'auth_required' || error.type === 'scope_missing') {
     return (
       <GhAuthErrorHelp
         error={error as GitHubProjectViewError & { type: 'auth_required' | 'scope_missing' }}
         variant="banner"
-        host="github.com"
+        host={host}
       />
     )
   }
diff --git a/src/renderer/src/components/github-project/project-picker-input.test.ts b/src/renderer/src/components/github-project/project-picker-input.test.ts
index 358f1947e90..68ae3eb89eb 100644
--- a/src/renderer/src/components/github-project/project-picker-input.test.ts
+++ b/src/renderer/src/components/github-project/project-picker-input.test.ts
@@ -1,5 +1,5 @@
 import { describe, expect, it } from 'vitest'
-import { parseProjectInput } from './ProjectPicker'
+import { getProjectPickerBrowseHost, parseProjectInput } from './ProjectPicker'
 
 describe('ProjectPicker project input', () => {
   it('preserves the host and custom port from a GHES project URL', () => {
@@ -17,6 +17,13 @@ describe('ProjectPicker project input', () => {
     expect(parseProjectInput('acme/7')).toEqual({ owner: 'acme', number: 7 })
   })
 
+  it('browses and reports auth errors against the active project host', () => {
+    expect(getProjectPickerBrowseHost({ host: ' GitHub.Corp.Example:8443 ' })).toBe(
+      'github.corp.example:8443'
+    )
+    expect(getProjectPickerBrowseHost(null)).toBe('github.com')
+  })
+
   it('rejects credentials and malformed Project routes', () => {
     for (const input of [
       'https://user:token@github.corp.example/orgs/acme/projects/7',
diff --git a/src/renderer/src/components/pull-request-page-host-boundary.test.ts b/src/renderer/src/components/pull-request-page-host-boundary.test.ts
index cc83a16e6f8..566ee235f25 100644
--- a/src/renderer/src/components/pull-request-page-host-boundary.test.ts
+++ b/src/renderer/src/components/pull-request-page-host-boundary.test.ts
@@ -36,7 +36,7 @@ describe('PullRequestPage host boundaries', () => {
     )
     expect(section).toContain("'github.requestPRReviewers'")
     expect(section).toContain("'github.removePRReviewers'")
-    expect(section).toContain('{ repo: runtimeRepo, prNumber: item.number, reviewers: logins }')
+    expect(section.match(/prRepo: item\.prRepo \?\? reviewSlug/g)).toHaveLength(4)
     expect(section).toContain('notifyWorkItemDetailsMutation(')
     expect(section).toContain('{ local: false }')
   })
@@ -231,7 +231,9 @@ describe('PullRequestPage host boundaries', () => {
     expect(source).toContain('options.local !== false')
     expect(source).toContain('notifyWorkItemMutated({')
     expect(commentContextSection).toContain('sourceContext?: TaskSourceContext | null')
-    expect(commentContextSection).toContain('sourceContext, prNumber')
+    expect(commentContextSection).toMatch(
+      /loadPRFileContents\(\{\s*repoPath,\s*repoId,\s*sourceContext,\s*prNumber,\s*prRepo,/
+    )
   })
 
   it('routes check actions through the PR source context', () => {