fix(browse): scope test 5's PowerShell assertion to the owner; identify a win32 agent by generation when readers disagree

Review of d4f0ea3c (specialist + outside voice, confirmed by Windows Free
Tests 40699973746 shard 3): test 5's fake child pid cannot be opened, so its
start time falls back to the PowerShell query; only the owner must skip it.
Adversarial note: the Bun reader and the Node daemon's PowerShell reader can
disagree for a process created in a DST-ambiguous hour; on win32 a live
process carrying the record's --agent-gen is still the agent, so it is
stopped, never treated as gone beside a second agent.

Co-authored-by: capy-ai[bot] <230910855+capy-ai[bot]@users.noreply.github.com>

browse/src/terminal-agent-control.ts

@@ -368,7 +368,8 @@ function agentStatus(record: AgentRecord, ownerPid?: number): 'owned' | 'gone' |
   if (ownerPid !== undefined && (record.ownerPid !== ownerPid || record.ownerStartTime !== readAgentStartTime(ownerPid))) return 'unknown';
   const actual = agentProcessInfo(record.pid);
   if (!actual.startTime) return isAgentRecordLive(record) ? 'unknown' : 'gone';
-  if (actual.startTime !== record.startTime) return 'gone';
+  const ownsGeneration = actual.commandLine.split(/\s+/).some(arg => arg.replace(/^['"]|['"]$/g, '') === `--agent-gen=${record.gen}`);
+  if (actual.startTime !== record.startTime && !(process.platform === 'win32' && ownsGeneration)) return 'gone';
   try {
     let state: string | undefined;
     if (process.platform === 'linux') {
@@ -380,8 +381,7 @@ function agentStatus(record: AgentRecord, ownerPid?: number): 'owned' | 'gone' |
     if (state === 'Z') return 'gone';
   } catch {}
   if (!isAgentRecordLive(record)) return 'gone';
-  return actual.commandLine.split(/\s+/).some(arg => arg.replace(/^['"]|['"]$/g, '') === `--agent-gen=${record.gen}`)
-    ? 'owned' : 'unknown';
+  return ownsGeneration ? 'owned' : 'unknown';
 }
 
 export function isOurAgent(record: AgentRecord, ownerPid?: number): boolean {

browse/test/process-liveness-windows.test.ts

@@ -151,7 +151,8 @@ describe('process liveness probe (Windows terminal-agent leak)', () => {
       if (process.platform === 'win32') {
         expect(captured.env.BROWSE_OWNER_START_TIME).toMatch(/^\/Date\(\d+\)\/$/);
         expect(captured.env.BROWSE_OWNER_START_TIME).toBe(readAgentStartTime(process.pid));
-        expect(powershellCalls).toEqual([]);
+        expect(powershellCalls.filter(call => call.includes(`ProcessId = ${process.pid}'`))).toEqual([]);
+        expect(powershellCalls.every(call => call.includes("ProcessId = 2147483647'"))).toBe(true);
       } else {
         expect(captured.env.BROWSE_OWNER_START_TIME).toBe('fixture-owner-start');
       }
@@ -252,12 +253,22 @@ describe('win32 terminal-agent identity (GSTA-139)', () => {
         expect(calls.signals).toEqual([]);
       });
     }
-    onWin32({ ffi: '/Date(1761600000124)/', powershell: { status: 0, creationDate: birth, commandLine: ownedCommand } }, calls => {
+    onWin32({ ffi: '/Date(1761600000124)/', powershell: { status: 0, creationDate: birth, commandLine: 'bun run unrelated.ts' } }, calls => {
       expect(isAgentRecordGone(record())).toBe(true);
       expect(calls.signals).toEqual([]);
     });
   });
 
+  test('a start time that disagrees across readers still identifies the live agent by its generation, so no second agent starts', () => {
+    const daemonRecorded = '/Date(1761596400123)/';
+    onWin32({ ffi: birth, powershell: { status: 0, creationDate: daemonRecorded, commandLine: ownedCommand } }, calls => {
+      expect(isAgentRecordGone(record(daemonRecorded))).toBe(false);
+      expect(isOurAgent(record(daemonRecorded))).toBe(true);
+      expect(stopAgentByRecord(record(daemonRecorded), 0)).toBe(true);
+      expect(calls.signals).toEqual(['SIGTERM']);
+    });
+  });
+
   test('an unreadable start time is unknown: never signalled and never treated as gone', () => {
     onWin32({ ffi: undefined, powershell: { status: null } }, calls => {
       expect(readAgentStartTime(pid)).toBe('');