fix(antigravity): use managed prompt file and update tests

Author: AadiyKhan

apps/daemon/src/runtimes/defs/antigravity.ts

@@ -5,7 +5,7 @@ import {
   writeFileSync,
 } from 'node:fs';
 import { readFile as fsReadFile } from 'node:fs/promises';
-import { homedir, tmpdir } from 'node:os';
+import { homedir } from 'node:os';
 import { dirname, join } from 'node:path';
 
 import { DEFAULT_MODEL_OPTION } from './shared.js';
@@ -217,22 +217,22 @@ export const antigravityAgentDef = {
     }
     // We no longer use `-p -` because recent `agy` versions treat `-` as a literal 
     // prompt string instead of reading from stdin (see issue #5495).
-    // Instead, we write the full transcript to a temporary file and instruct 
-    // `agy` to read and execute it, avoiding Windows command-line length limits.
-    // We use a PID-bound filename so it safely overwrites itself on each turn
-    // without bloating the OS temp directory over time.
-    const tempFile = join(tmpdir(), `od_agy_prompt_${process.pid}.md`);
-    writeFileSync(tempFile, _prompt);
+    // Instead, we use `promptViaFile: true` so the daemon securely prepares a 
+    // managed temp file per-run and cleans it up after the agent exits.
+    if (!runtimeContext.promptFilePath) {
+      throw new Error('antigravity requires runtimeContext.promptFilePath when promptViaFile is true');
+    }
 
     const args: string[] = [];
     if (runtimeContext.agentLogFilePath) {
       args.push('--log-file', runtimeContext.agentLogFilePath);
     }
     args.push('-p');
-    args.push(`Read the system instructions, conversation history, and user request from the file ${tempFile}. Follow the instructions strictly and provide the final response to the user's latest request.`);
+    args.push(`Read the system instructions, conversation history, and user request from the file ${runtimeContext.promptFilePath}. Follow the instructions strictly and provide the final response to the user's latest request.`);
     return args;
   },
   promptViaStdin: false,
+  promptViaFile: true,
   streamFormat: 'plain',
   installUrl: 'https://antigravity.google/cli',
   docsUrl: 'https://antigravity.google/docs/cli-overview',

apps/daemon/tests/runtimes/agent-args.test.ts

@@ -534,18 +534,28 @@ test('qwen args check promptViaStdin, base args, model args and exclude `-` sent
 // the daemon would render the resulting empty reply as a "successful"
 // agent response — exactly the failure mode the auth/quota guard at
 // server.ts ~12090 is meant to catch but for the wrong reason.
-test('antigravity pipes prompt via stdin via -p flag (print mode)', () => {
+test('antigravity delivers prompt via managed temp file instead of stdin', () => {
   assert.equal(antigravity.bin, 'agy');
   assert.equal(antigravity.streamFormat, 'plain');
-  assert.equal(antigravity.promptViaStdin, true);
+  assert.equal(antigravity.promptViaStdin, false);
+  assert.equal(antigravity.promptViaFile, true);
 
-  const args = antigravity.buildArgs('write hello world', [], [], {}, {});
-  assert.deepEqual(args, ['-p', '-']);
+  assert.throws(() => {
+    antigravity.buildArgs('hello', [], [], {}, {});
+  }, /requires runtimeContext\.promptFilePath/);
+
+  const expectedFileText = 'Read the system instructions, conversation history, and user request from the file /tmp/managed-prompt.md. Follow the instructions strictly and provide the final response to the user\'s latest request.';
+
+  const args = antigravity.buildArgs('write hello world', [], [], {}, {
+    promptFilePath: '/tmp/managed-prompt.md'
+  });
+  assert.deepEqual(args, ['-p', expectedFileText]);
 
   const argsWithLog = antigravity.buildArgs('write hello world', [], [], {}, {
     agentLogFilePath: '/tmp/od-agy-test.log',
+    promptFilePath: '/tmp/managed-prompt.md'
   });
-  assert.deepEqual(argsWithLog, ['--log-file', '/tmp/od-agy-test.log', '-p', '-']);
+  assert.deepEqual(argsWithLog, ['--log-file', '/tmp/od-agy-test.log', '-p', expectedFileText]);
 
   // No `--model` flag exists upstream, so buildArgs argv must stay the
   // same regardless of which label the user picks.
@@ -558,9 +568,10 @@ test('antigravity pipes prompt via stdin via -p flag (print mode)', () => {
     }, {
       agentLogFilePath: '/tmp/od-agy-test.log',
       antigravitySettingsPath: join(settingsDir, 'settings.json'),
+      promptFilePath: '/tmp/managed-prompt.md'
     });
     assert.equal(withModel.includes('--model'), false);
-    assert.deepEqual(withModel, ['--log-file', '/tmp/od-agy-test.log', '-p', '-']);
+    assert.deepEqual(withModel, ['--log-file', '/tmp/od-agy-test.log', '-p', expectedFileText]);
   } finally {
     rmSync(settingsDir, { recursive: true, force: true });
   }
@@ -575,14 +586,16 @@ test('antigravity pipes prompt via stdin via -p flag (print mode)', () => {
   // same regression.
   const followUp = antigravity.buildArgs('next message', [], [], {}, {
     hasPriorAssistantTurn: true,
+    promptFilePath: '/tmp/managed-prompt.md'
   });
-  assert.deepEqual(followUp, ['-p', '-']);
+  assert.deepEqual(followUp, ['-p', expectedFileText]);
   assert.equal(followUp.includes('-c'), false);
 
   const firstTurn = antigravity.buildArgs('first', [], [], {}, {
     hasPriorAssistantTurn: false,
+    promptFilePath: '/tmp/managed-prompt.md'
   });
-  assert.deepEqual(firstTurn, ['-p', '-']);
+  assert.deepEqual(firstTurn, ['-p', expectedFileText]);
   assert.equal(antigravity.resumesSessionViaCli, undefined);
 
   assert.equal(antigravity.maxPromptArgBytes, undefined);