fix(subagent): expose startup cleanup failure facts

packages/subagent/subagent-claude-code/src/run.ts

@@ -453,9 +453,10 @@ export async function startClaudeCodeRun(
         await disposeClaudeCodeChild(query, child)
       } catch (disposeError: unknown) {
         const failure = startupFailure()
+        const cleanupFailure = thrown(disposeError)
         throw new AggregateError(
-          [failure, thrown(disposeError)],
-          `${failure.message}; startup cleanup also failed`,
+          [failure, cleanupFailure],
+          `${failure.message}; ${cleanupFailure.message}`,
         )
       }
     } else if (query !== undefined) {
@@ -463,15 +464,13 @@ export async function startClaudeCodeRun(
         query.close()
       } catch (disposeError: unknown) {
         const failure = startupFailure()
+        const cleanupFailure = new ClaudeCodeFailure({
+          stage: 'teardown',
+          category: 'unknown',
+        }, thrown(disposeError))
         throw new AggregateError(
-          [
-            failure,
-            new ClaudeCodeFailure({
-              stage: 'teardown',
-              category: 'unknown',
-            }, thrown(disposeError)),
-          ],
-          `${failure.message}; startup cleanup also failed`,
+          [failure, cleanupFailure],
+          `${failure.message}; ${cleanupFailure.message}`,
         )
       }
     }

packages/subagent/subagent-claude-code/tests/subagent-claude-code.spec.ts

@@ -1087,6 +1087,9 @@ describe('run publication, cancellation, and settlement', () => {
     })
     await expect(noChild)
       .rejects.toThrow(expectedFailureDiagnostic('query-start', 'unknown'))
+    await expect(noChild).rejects.toThrow(
+      `${expectedFailureDiagnostic('query-start', 'unknown')}; subagent-claude-code: ${expectedFailureDiagnostic('teardown', 'unknown')}`,
+    )
     await expect(noChild).rejects.toBeInstanceOf(AggregateError)
 
     const startupAbort = new AbortController()
@@ -1129,6 +1132,9 @@ describe('run publication, cancellation, and settlement', () => {
       .rejects.toBeInstanceOf(AggregateError)
     await expect(cancelledCleanupFailure)
       .rejects.toThrow(expectedFailureDiagnostic('query-start', 'unknown'))
+    await expect(cancelledCleanupFailure).rejects.toThrow(
+      `${expectedFailureDiagnostic('query-start', 'unknown')}; subagent-claude-code: ${expectedFailureDiagnostic('teardown', 'unknown', { exitCode: 0, signal: null })}`,
+    )
     await expect(cancelledCleanupFailure)
       .rejects.not.toThrow('SECRET_TOKEN')
 
@@ -1196,6 +1202,9 @@ describe('run publication, cancellation, and settlement', () => {
     const failedStartup = startClaudeCodeRun(request(), failed.spec)
     await expect(failedStartup)
       .rejects.toThrow(expectedFailureDiagnostic('query-start', 'unknown'))
+    await expect(failedStartup).rejects.toThrow(
+      `${expectedFailureDiagnostic('query-start', 'unknown')}; subagent-claude-code: ${expectedFailureDiagnostic('teardown', 'unknown')}`,
+    )
     await expect(failedStartup).rejects.toBeInstanceOf(AggregateError)
     expect(failed.close).toHaveBeenCalledOnce()
   })