fix(agents): suppress exec/bash exit code errors from user display

Exec/bash tool errors with non-zero exit codes (e.g., grep no matches,
command not found) are now treated as internal/recoverable errors and
not displayed to users.

These errors are expected workflow results that the model should handle
internally, not technical failures that need user attention.

Fixes #3765

src/agents/pi-embedded-runner/run/payloads.test.ts

@@ -171,10 +171,41 @@ describe("buildEmbeddedRunPayloads", () => {
       toolResultFormat: "plain",
     });
 
-    expect(payloads).toHaveLength(1);
-    expect(payloads[0]?.isError).toBe(true);
-    expect(payloads[0]?.text).toContain("Exec");
-    expect(payloads[0]?.text).toContain("code 1");
+    // Exec exit code errors are now suppressed as internal/recoverable errors
+    expect(payloads).toHaveLength(0);
+  });
+
+  it("suppresses exec exit code errors (grep no matches, etc.)", () => {
+    const payloads = buildEmbeddedRunPayloads({
+      assistantTexts: [],
+      toolMetas: [],
+      lastAssistant: undefined,
+      lastToolError: { toolName: "exec", error: "Command exited with code 1" },
+      sessionKey: "session:telegram",
+      inlineToolResultsAllowed: false,
+      verboseLevel: "off",
+      reasoningLevel: "off",
+      toolResultFormat: "plain",
+    });
+
+    // Exec/bash exit code errors should not be sent to the user
+    expect(payloads).toHaveLength(0);
+  });
+
+  it("suppresses bash exit code errors", () => {
+    const payloads = buildEmbeddedRunPayloads({
+      assistantTexts: [],
+      toolMetas: [],
+      lastAssistant: undefined,
+      lastToolError: { toolName: "bash", error: "Command exited with code 127" },
+      sessionKey: "session:telegram",
+      inlineToolResultsAllowed: false,
+      verboseLevel: "off",
+      reasoningLevel: "off",
+      toolResultFormat: "plain",
+    });
+
+    expect(payloads).toHaveLength(0);
   });
 
   it("suppresses recoverable tool errors containing 'required'", () => {

src/agents/pi-embedded-runner/run/payloads.ts

@@ -182,7 +182,13 @@ export function buildEmbeddedRunPayloads(params: {
     // Check if this is a recoverable/internal tool error that shouldn't be shown to users
     // when there's already a user-facing reply (the model should have retried).
     const errorLower = (params.lastToolError.error ?? "").toLowerCase();
+    const toolNameLower = (params.lastToolError.toolName ?? "").toLowerCase();
+    const isExecTool = toolNameLower === "exec" || toolNameLower === "bash";
+    // Exec/bash non-zero exit codes are internal errors (e.g., grep no matches) that
+    // the model should handle, not surface to users.
+    const isExecExitCodeError = isExecTool && errorLower.includes("exited with code");
     const isRecoverableError =
+      isExecExitCodeError ||
       errorLower.includes("required") ||
       errorLower.includes("missing") ||
       errorLower.includes("invalid") ||