fix(exec): prevent PATH injection in docker sandbox

docs/tools/exec.md

@@ -67,7 +67,8 @@ Example:
   - macOS: `/opt/homebrew/bin`, `/usr/local/bin`, `/usr/bin`, `/bin`
   - Linux: `/usr/local/bin`, `/usr/bin`, `/bin`
 - `host=sandbox`: runs `sh -lc` (login shell) inside the container, so `/etc/profile` may reset `PATH`.
-  Clawdbot prepends `env.PATH` after profile sourcing; `tools.exec.pathPrepend` applies here too.
+  Clawdbot prepends `env.PATH` after profile sourcing via an internal env var (no shell interpolation);
+  `tools.exec.pathPrepend` applies here too.
 - `host=node`: only env overrides you pass are sent to the node. `tools.exec.pathPrepend` only applies
   if the exec call already sets `env.PATH`. Headless node hosts accept `PATH` only when it prepends
   the node host PATH (no replacement). macOS nodes drop `PATH` overrides entirely.

src/agents/bash-tools.shared.ts

@@ -60,11 +60,18 @@ export function buildDockerExecArgs(params: {
   for (const [key, value] of Object.entries(params.env)) {
     args.push("-e", `${key}=${value}`);
   }
+  const hasCustomPath = typeof params.env.PATH === "string" && params.env.PATH.length > 0;
+  if (hasCustomPath) {
+    // Avoid interpolating PATH into the shell command; pass it via env instead.
+    args.push("-e", `CLAWDBOT_PREPEND_PATH=${params.env.PATH}`);
+  }
   // Login shell (-l) sources /etc/profile which resets PATH to a minimal set,
   // overriding both Docker ENV and -e PATH=... environment variables.
   // Prepend custom PATH after profile sourcing to ensure custom tools are accessible
   // while preserving system paths that /etc/profile may have added.
-  const pathExport = params.env.PATH ? `export PATH="${params.env.PATH}:$PATH"; ` : "";
+  const pathExport = hasCustomPath
+    ? 'export PATH="${CLAWDBOT_PREPEND_PATH}:$PATH"; unset CLAWDBOT_PREPEND_PATH; '
+    : "";
   args.push(params.containerName, "sh", "-lc", `${pathExport}${params.command}`);
   return args;
 }

src/agents/bash-tools.test.ts

@@ -318,9 +318,30 @@ describe("buildDockerExecArgs", () => {
     });
 
     const commandArg = args[args.length - 1];
-    expect(commandArg).toContain('export PATH="/custom/bin:/usr/local/bin:/usr/bin:$PATH"');
+    expect(args).toContain("CLAWDBOT_PREPEND_PATH=/custom/bin:/usr/local/bin:/usr/bin");
+    expect(commandArg).toContain('export PATH="${CLAWDBOT_PREPEND_PATH}:$PATH"');
     expect(commandArg).toContain("echo hello");
-    expect(commandArg).toBe('export PATH="/custom/bin:/usr/local/bin:/usr/bin:$PATH"; echo hello');
+    expect(commandArg).toBe(
+      'export PATH="${CLAWDBOT_PREPEND_PATH}:$PATH"; unset CLAWDBOT_PREPEND_PATH; echo hello',
+    );
+  });
+
+  it("does not interpolate PATH into the shell command", () => {
+    const injectedPath = "$(touch /tmp/clawdbot-path-injection)";
+    const args = buildDockerExecArgs({
+      containerName: "test-container",
+      command: "echo hello",
+      env: {
+        PATH: injectedPath,
+        HOME: "/home/user",
+      },
+      tty: false,
+    });
+
+    const commandArg = args[args.length - 1];
+    expect(args).toContain(`CLAWDBOT_PREPEND_PATH=${injectedPath}`);
+    expect(commandArg).not.toContain(injectedPath);
+    expect(commandArg).toContain("CLAWDBOT_PREPEND_PATH");
   });
 
   it("does not add PATH export when PATH is not in env", () => {