fix: show tool error fallback for tool-only replies

CHANGELOG.md

@@ -23,6 +23,8 @@ Docs: https://docs.clawd.bot
 ### Fixes
 - Gateway: compare Linux process start time to avoid PID recycling lock loops; keep locks unless stale. (#1572) Thanks @steipete.
 - Skills: gate bird Homebrew install to macOS. (#1569) Thanks @bradleypriest.
+- Slack: honor open groupPolicy for unlisted channels in message + slash gating. (#1563) Thanks @itsjaydesu.
+- Agents: show tool error fallback when the last assistant turn only invoked tools (prevents silent stops).
 - Agents: ignore IDENTITY.md template placeholders when parsing identity to avoid placeholder replies. (#1556)
 - Agents: drop orphaned OpenAI Responses reasoning blocks on model switches. (#1562) Thanks @roshanasingh4.
 - Docker: update gateway command in docker-compose and Hetzner guide. (#1514)

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

@@ -148,6 +148,35 @@ describe("buildEmbeddedRunPayloads", () => {
     expect(payloads[0]?.text).toBe("All good");
   });
 
+  it("adds tool error fallback when the assistant only invoked tools", () => {
+    const payloads = buildEmbeddedRunPayloads({
+      assistantTexts: [],
+      toolMetas: [],
+      lastAssistant: {
+        stopReason: "toolUse",
+        content: [
+          {
+            type: "toolCall",
+            id: "toolu_01",
+            name: "exec",
+            arguments: { command: "echo hi" },
+          },
+        ],
+      } as AssistantMessage,
+      lastToolError: { toolName: "exec", error: "Command exited with code 1" },
+      sessionKey: "session:telegram",
+      inlineToolResultsAllowed: false,
+      verboseLevel: "off",
+      reasoningLevel: "off",
+      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");
+  });
+
   it("suppresses recoverable tool errors containing 'required'", () => {
     const payloads = buildEmbeddedRunPayloads({
       assistantTexts: [],

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

@@ -169,7 +169,16 @@ export function buildEmbeddedRunPayloads(params: {
   }
 
   if (params.lastToolError) {
-    const hasUserFacingReply = replyItems.length > 0;
+    const lastAssistantHasToolCalls =
+      Array.isArray(params.lastAssistant?.content) &&
+      params.lastAssistant?.content.some((block) =>
+        block && typeof block === "object"
+          ? (block as { type?: unknown }).type === "toolCall"
+          : false,
+      );
+    const lastAssistantWasToolUse = params.lastAssistant?.stopReason === "toolUse";
+    const hasUserFacingReply =
+      replyItems.length > 0 && !lastAssistantHasToolCalls && !lastAssistantWasToolUse;
     // 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();