fix(sandbox): round 6 bind spawn provenance

packages/bash/bash-sandbox/src/helpers.ts

@@ -23,10 +23,11 @@ function isUsableWorkdir(path: string): boolean {
 }
 
 /**
- * Attribute only executable-class failures with Node spawn provenance after
- * independently ruling out the caller-owned cwd. With a usable cwd, these
- * codes describe resolution, permissions, or loading of the provider's
- * argv[0], including a script whose shebang interpreter is unavailable.
+ * Attribute only executable-class failures with positive Node argv[0]
+ * provenance after independently ruling out the caller-owned cwd. A supplied
+ * error path must exactly identify the runner; without one, the syscall must.
+ * With a usable cwd, these codes describe resolution, permissions, or loading
+ * of that argv[0], including a script whose shebang interpreter is unavailable.
  * @param error - the original spawn rejection.
  * @param runnerProgram - provider argv[0], the executable that establishes confinement.
  * @param workdir - the caller-owned spawn cwd, checked independently for usability.
@@ -41,9 +42,11 @@ export function isRunnerSpawnFailure(
   if (typeof error !== 'object' || error === null) return false
   const { code, path, syscall } = error as { code?: unknown; path?: unknown; syscall?: unknown }
   if (typeof code !== 'string' || !EXECUTABLE_SPAWN_CODES.has(code)) return false
-  if (typeof syscall !== 'string' || (syscall !== 'spawn' && !syscall.startsWith('spawn '))) return false
-  if (path !== undefined && (typeof path !== 'string' || (path.length > 0 && path !== runnerProgram))) return false
-  return true
+  if (typeof syscall !== 'string') return false
+  const exactSyscall = `spawn ${runnerProgram}`
+  if (path === undefined) return syscall === exactSyscall
+  if (typeof path !== 'string' || path.length === 0 || path !== runnerProgram) return false
+  return syscall === 'spawn' || syscall === exactSyscall
 }
 
 /** Fatal runner evidence retained for infrastructure-error detail. */

packages/bash/bash-sandbox/tests/sandbox.spec.ts

@@ -384,6 +384,8 @@ describe('isRunnerSpawnFailure', () => {
     const missingRunner = join(spillDir, 'definitely-missing-runner')
     const spawnError = (code: unknown, syscall: unknown = `spawn ${missingRunner}`, path: unknown = missingRunner) =>
       Object.assign(new Error('spawn failed'), { code, syscall, path })
+    const spawnErrorWithoutPath = (syscall: string) =>
+      Object.assign(new Error('spawn failed'), { code: 'ENOENT', syscall })
 
     expect(isRunnerSpawnFailure(spawnError('EMFILE'), missingRunner, process.cwd())).toBe(false)
     expect(isRunnerSpawnFailure(spawnError('ENOMEM'), missingRunner, process.cwd())).toBe(false)
@@ -392,12 +394,24 @@ describe('isRunnerSpawnFailure', () => {
     expect(isRunnerSpawnFailure(spawnError('ENOENT', 1), missingRunner, process.cwd())).toBe(false)
     expect(isRunnerSpawnFailure(spawnError('ENOENT', 'spawn', process.execPath), missingRunner, process.cwd())).toBe(false)
     expect(isRunnerSpawnFailure(spawnError('ENOENT', 'spawn', 1), missingRunner, process.cwd())).toBe(false)
-    expect(isRunnerSpawnFailure(spawnError('ENOENT', 'spawn', ''), missingRunner, process.cwd())).toBe(true)
-    expect(isRunnerSpawnFailure(spawnError('ENOENT', 'spawn', undefined), missingRunner, process.cwd())).toBe(true)
+    expect(isRunnerSpawnFailure(spawnError('ENOENT', 'spawn', ''), missingRunner, process.cwd())).toBe(false)
+    expect(isRunnerSpawnFailure(spawnErrorWithoutPath('spawn'), missingRunner, process.cwd())).toBe(false)
+    expect(isRunnerSpawnFailure(spawnErrorWithoutPath('spawn other-runner'), missingRunner, process.cwd())).toBe(false)
     expect(isRunnerSpawnFailure(undefined, missingRunner, process.cwd())).toBe(false)
     expect(isRunnerSpawnFailure(null, missingRunner, process.cwd())).toBe(false)
     expect(isRunnerSpawnFailure(spawnError('ENOENT'), undefined, process.cwd())).toBe(false)
   })
+
+  it('accepts only syscall provenance compatible with the exact runner program', () => {
+    const runner = join(spillDir, 'runner with spaces')
+    const spawnError = (syscall: string, path?: string) =>
+      Object.assign(new Error('spawn failed'), { code: 'ENOEXEC', syscall, path })
+
+    expect(isRunnerSpawnFailure(spawnError('spawn', runner), runner, process.cwd())).toBe(true)
+    expect(isRunnerSpawnFailure(spawnError(`spawn ${runner}`, runner), runner, process.cwd())).toBe(true)
+    expect(isRunnerSpawnFailure(spawnError(`spawn ${runner}`), runner, process.cwd())).toBe(true)
+    expect(isRunnerSpawnFailure(spawnError('spawn other-runner', runner), runner, process.cwd())).toBe(false)
+  })
 })
 
 describe('classifyRunnerFailure', () => {