fix(git): preserve SSH review context and worktree ownership (#24945)

* fix(git): preserve SSH arguments and guard background writes

* test(terminal): settle fish fixture startup readiness

* fix(git): preserve bare UNC SSH paths

* fix(git): unescape shell operators in Windows SSH paths

* test(runtime): settle removal writes before fixture cleanup

* test(git): skip optional OpenSSH probe when unavailable

* perf(git): skip equal-tip reads and bound relay discovery

* test(processes): ratchet the removed relay Git spawn

* test(shells): wait for initial zsh output before sending input

* Fix SSH review context and recover Git maintenance cleanup safely

* Keep relay Git compatibility fixtures outside shared client projects

* Fence superseded maintenance and preserve mixed-version session search

* test: model Git child termination and search catalogs

* test: retain catalog authority over history flags

src/main/git/command-runner/git-exec-file.ts

@@ -27,6 +27,7 @@ import { nonInteractiveGitEnv, untranslatedGitOutputEnv } from './git-process-en
 import { acquireGitAdmission } from './git-subprocess-admission'
 import { GitCommandTimeoutError, gitCommandTimeoutMs } from './git-command-timeout'
 import { classifyGitCommand } from '../../../shared/git-command-classification'
+import { createAbortError } from './abort-error'
 
 /**
  * Async git command execution. Drop-in replacement for
@@ -74,7 +75,7 @@ async function gitExecFileAsyncUnlocked(
             cwd: options.cwd,
             wslDistro: options.wslDistro,
             tier: options.admissionTier,
-            signal: options.signal
+            signal: options.admissionSignal ?? options.signal
           })
       span?.setAttribute('git.queue_wait_ms', grant.queueWaitMs)
       const timeoutMs = gitCommandTimeoutMs(args, options.timeout, options.timeoutMsForTest)
@@ -153,6 +154,10 @@ async function gitExecFileAsyncUnlocked(
         }
       }
       try {
+        options.admissionSignal?.throwIfAborted()
+        if (options.canStart?.() === false) {
+          throw createAbortError()
+        }
         return await runCapturedCommand()
       } finally {
         const termination = terminationState.current

src/main/git/command-runner/git-exec-options.ts

@@ -16,6 +16,10 @@ export type GitExecOptions = {
   stdin?: string
   env?: NodeJS.ProcessEnv
   signal?: AbortSignal
+  /** Cancels admission only; a running child still finishes. */
+  admissionSignal?: AbortSignal
+  /** Rechecks owner eligibility after admission, before starting the child. */
+  canStart?: () => boolean
   wslDistro?: string
   preferWslDirectGit?: boolean
   useConfiguredSshCommandForNetwork?: boolean