Mitigate ARG_MAX/E2BIG by rewriting inline prompt expansion to stdin in AWF agent command

src/docker-manager.test.ts

@@ -1295,6 +1295,94 @@ describe('docker-manager', () => {
       expect(agent.command).toEqual(['/bin/bash', '-c', 'echo $$HOME && echo $${USER}']);
     });
 
+    it('should rewrite inline --prompt $(cat ...) to stdin redirect to avoid ARG_MAX expansion', () => {
+      const configWithInlinePrompt = {
+        ...mockConfig,
+        agentCommand: 'node /tmp/gh-aw/actions/copilot_driver.cjs /usr/local/bin/copilot --prompt "$(cat /tmp/gh-aw/aw-prompts/prompt.txt)" --allow-all-tools',
+      };
+      const result = generateDockerCompose(configWithInlinePrompt, mockNetworkConfig);
+      const agent = result.services.agent;
+
+      expect(agent.command).toEqual([
+        '/bin/bash',
+        '-c',
+        'node /tmp/gh-aw/actions/copilot_driver.cjs /usr/local/bin/copilot --prompt - < /tmp/gh-aw/aw-prompts/prompt.txt --allow-all-tools',
+      ]);
+    });
+
+    it('should rewrite inline --prompt $(cat ...) when cat path is single-quoted', () => {
+      const configWithQuotedPath = {
+        ...mockConfig,
+        agentCommand: 'node /tmp/gh-aw/actions/copilot_driver.cjs /usr/local/bin/copilot --prompt "$(cat \'/tmp/gh-aw/aw-prompts/prompt with spaces.txt\')" --allow-all-tools',
+      };
+      const result = generateDockerCompose(configWithQuotedPath, mockNetworkConfig);
+      const agent = result.services.agent;
+
+      expect(agent.command).toEqual([
+        '/bin/bash',
+        '-c',
+        'node /tmp/gh-aw/actions/copilot_driver.cjs /usr/local/bin/copilot --prompt - < \'/tmp/gh-aw/aw-prompts/prompt with spaces.txt\' --allow-all-tools',
+      ]);
+    });
+
+    it('should rewrite unquoted --prompt $(cat ...) form', () => {
+      const configWithUnquotedInlinePrompt = {
+        ...mockConfig,
+        agentCommand: 'node /tmp/gh-aw/actions/copilot_driver.cjs /usr/local/bin/copilot --prompt $(cat /tmp/gh-aw/aw-prompts/prompt.txt) --allow-all-tools',
+      };
+      const result = generateDockerCompose(configWithUnquotedInlinePrompt, mockNetworkConfig);
+      const agent = result.services.agent;
+
+      expect(agent.command).toEqual([
+        '/bin/bash',
+        '-c',
+        'node /tmp/gh-aw/actions/copilot_driver.cjs /usr/local/bin/copilot --prompt - < /tmp/gh-aw/aw-prompts/prompt.txt --allow-all-tools',
+      ]);
+    });
+
+    it('should not rewrite regular literal --prompt values', () => {
+      const configWithLiteralPrompt = {
+        ...mockConfig,
+        agentCommand: 'copilot --prompt "hello world"',
+      };
+      const result = generateDockerCompose(configWithLiteralPrompt, mockNetworkConfig);
+      const agent = result.services.agent;
+
+      expect(agent.command).toEqual(['/bin/bash', '-c', 'copilot --prompt "hello world"']);
+    });
+
+    it('should preserve shell variable expansion in prompt paths', () => {
+      const configWithVarPath = {
+        ...mockConfig,
+        agentCommand: 'node driver.cjs copilot --prompt "$(cat "$RUNNER_TEMP/prompt.txt")" --allow-all-tools',
+      };
+      const result = generateDockerCompose(configWithVarPath, mockNetworkConfig);
+      const agent = result.services.agent;
+
+      // Env-var path must NOT be single-quoted; $RUNNER_TEMP must expand at runtime
+      expect(agent.command).toEqual([
+        '/bin/bash',
+        '-c',
+        'node driver.cjs copilot --prompt - < "$$RUNNER_TEMP/prompt.txt" --allow-all-tools',
+      ]);
+    });
+
+    it('should preserve compound command semantics when rewriting prompt', () => {
+      const configWithPipeline = {
+        ...mockConfig,
+        agentCommand: 'node driver.cjs copilot --prompt "$(cat /tmp/prompt.txt)" --allow-all-tools 2>&1 | tee -a /tmp/agent-stdio.log',
+      };
+      const result = generateDockerCompose(configWithPipeline, mockNetworkConfig);
+      const agent = result.services.agent;
+
+      // Input redirection is in-place; the trailing pipeline is preserved
+      expect(agent.command).toEqual([
+        '/bin/bash',
+        '-c',
+        'node driver.cjs copilot --prompt - < /tmp/prompt.txt --allow-all-tools 2>&1 | tee -a /tmp/agent-stdio.log',
+      ]);
+    });
+
     it('should pass through GITHUB_TOKEN when present in environment', () => {
       const originalEnv = process.env.GITHUB_TOKEN;
       process.env.GITHUB_TOKEN = 'ghp_testtoken123';

src/docker-manager.ts

@@ -51,6 +51,78 @@ let agentExternallyKilled = false;
  */
 let awfDockerHostOverride: string | undefined;
 
+function trimMatchingOuterQuotes(value: string): string {
+  const trimmed = value.trim();
+  if (
+    (trimmed.startsWith('\'') && trimmed.endsWith('\'')) ||
+    (trimmed.startsWith('"') && trimmed.endsWith('"'))
+  ) {
+    return trimmed.slice(1, -1);
+  }
+  return trimmed;
+}
+
+function findInlinePromptCatRange(command: string): { start: number; end: number; promptPath: string; rawPromptPath: string } | null {
+  // Variant 1: --prompt "$(cat /path/to/prompt.txt)"
+  const quotedPrefix = '--prompt "$(cat ';
+  const quotedStart = command.indexOf(quotedPrefix);
+  if (quotedStart !== -1) {
+    const pathStart = quotedStart + quotedPrefix.length;
+    const pathEnd = command.indexOf(')"', pathStart);
+    if (pathEnd !== -1) {
+      return {
+        start: quotedStart,
+        end: pathEnd + 2,
+        promptPath: trimMatchingOuterQuotes(command.slice(pathStart, pathEnd)),
+        rawPromptPath: command.slice(pathStart, pathEnd).trim(),
+      };
+    }
+  }
+
+  // Variant 2: --prompt $(cat /path/to/prompt.txt)
+  const unquotedPrefix = '--prompt $(cat ';
+  const unquotedStart = command.indexOf(unquotedPrefix);
+  if (unquotedStart !== -1) {
+    const pathStart = unquotedStart + unquotedPrefix.length;
+    const pathEnd = command.indexOf(')', pathStart);
+    if (pathEnd !== -1) {
+      return {
+        start: unquotedStart,
+        end: pathEnd + 1,
+        promptPath: trimMatchingOuterQuotes(command.slice(pathStart, pathEnd)),
+        rawPromptPath: command.slice(pathStart, pathEnd).trim(),
+      };
+    }
+  }
+
+  return null;
+}
+
+/**
+ * Rewrites inline prompt expansions of the form:
+ *   --prompt "$(cat /path/to/prompt.txt)"
+ * to:
+ *   --prompt - < /path/to/prompt.txt
+ *
+ * Uses in-place input redirection (`< file`) instead of prepending `cat |`,
+ * which preserves shell semantics for compound commands (pipes, `&&`, `;`).
+ * The original path quoting/expansion is preserved so env-var paths like
+ * `"$GH_AW_PROMPT"` continue to expand correctly.
+ */
+function rewriteInlinePromptCatToStdin(agentCommand: string): string {
+  const inlinePrompt = findInlinePromptCatRange(agentCommand);
+  if (!inlinePrompt) return agentCommand;
+
+  const rawPath = inlinePrompt.rawPromptPath;
+  if (!rawPath) return agentCommand;
+
+  const rewrittenCommand = `${agentCommand.slice(0, inlinePrompt.start)}--prompt - < ${rawPath}${agentCommand.slice(inlinePrompt.end)}`;
+  if (rewrittenCommand === agentCommand) return agentCommand;
+
+  logger.warn(`Rewriting inline prompt expansion to stdin redirect to avoid ARG_MAX/E2BIG: ${rawPath}`);
+  return rewrittenCommand;
+}
+
 /**
  * Sets the Docker host to use for AWF's own container operations.
  *
@@ -602,6 +674,7 @@ export function generateDockerCompose(
   squidConfigContent?: string
 ): DockerComposeConfig {
   const projectRoot = path.join(__dirname, '..');
+  const rewrittenAgentCommand = rewriteInlinePromptCatToStdin(config.agentCommand);
 
   // Guard: --build-local requires full repo checkout (not available in standalone bundle)
   if (config.buildLocal) {
@@ -1024,10 +1097,14 @@ export function generateDockerCompose(
   if (config.envAll) {
     const totalEnvBytes = Object.entries(environment)
       .reduce((sum, [k, v]) => sum + k.length + (v?.length ?? 0) + 2, 0); // +2 for '=' and null
-    if (totalEnvBytes > ENV_SIZE_WARNING_THRESHOLD) {
+    const argvBytes = ['/bin/bash', '-c', rewrittenAgentCommand]
+      .reduce((sum, arg) => sum + arg.length + 1, 0); // +1 for each argv null terminator
+    const totalArgvEnvBytes = totalEnvBytes + argvBytes;
+    if (totalArgvEnvBytes > ENV_SIZE_WARNING_THRESHOLD) {
       logger.warn(
-        `⚠️  Total container environment size is ${(totalEnvBytes / 1024).toFixed(0)} KB — ` +
-        'may cause E2BIG (Argument list too long) errors when combined with large command arguments'
+        `⚠️  Estimated argv+env size is ${(totalArgvEnvBytes / 1024).toFixed(0)} KB ` +
+        `(env ${(totalEnvBytes / 1024).toFixed(0)} KB, argv ${(argvBytes / 1024).toFixed(0)} KB) — ` +
+        'may cause E2BIG (Argument list too long) errors'
       );
       logger.warn('   Consider using --exclude-env to remove unnecessary variables');
     }
@@ -1565,7 +1642,7 @@ export function generateDockerCompose(
       start_period: '1s',
     },
     // Escape $ with $$ for Docker Compose variable interpolation
-    command: ['/bin/bash', '-c', config.agentCommand.replace(/\$/g, '$$$$')],
+    command: ['/bin/bash', '-c', rewrittenAgentCommand.replace(/\$/g, '$$$$')],
   };
 
   // Set working directory if specified (overrides Dockerfile WORKDIR)