fix(agents): cap embedded runner retry loop

src/agents/pi-embedded-runner/run.overflow-compaction.test.ts

@@ -1,5 +1,6 @@
 import "./run.overflow-compaction.mocks.shared.js";
 import { beforeEach, describe, expect, it, vi } from "vitest";
+import { pickFallbackThinkingLevel } from "../pi-embedded-helpers.js";
 import { compactEmbeddedPiSessionDirect } from "./compact.js";
 import { runEmbeddedPiAgent } from "./run.js";
 import { makeAttemptResult, mockOverflowRetrySuccess } from "./run.overflow-compaction.fixture.js";
@@ -16,6 +17,7 @@ const mockedSessionLikelyHasOversizedToolResults = vi.mocked(sessionLikelyHasOve
 const mockedTruncateOversizedToolResultsInSession = vi.mocked(
   truncateOversizedToolResultsInSession,
 );
+const mockedPickFallbackThinkingLevel = vi.mocked(pickFallbackThinkingLevel);
 
 describe("runEmbeddedPiAgent overflow compaction trigger routing", () => {
   beforeEach(() => {
@@ -106,4 +108,29 @@ describe("runEmbeddedPiAgent overflow compaction trigger routing", () => {
     expect(mockedRunEmbeddedAttempt).toHaveBeenCalledTimes(4);
     expect(result.meta.error?.kind).toBe("context_overflow");
   });
+
+  it("returns retry_limit when repeated retries never converge", async () => {
+    mockedRunEmbeddedAttempt.mockReset();
+    mockedCompactDirect.mockReset();
+    mockedPickFallbackThinkingLevel.mockReset();
+    mockedRunEmbeddedAttempt.mockResolvedValue(
+      makeAttemptResult({ promptError: new Error("unsupported reasoning mode") }),
+    );
+    mockedPickFallbackThinkingLevel.mockReturnValue("low");
+
+    const result = await runEmbeddedPiAgent({
+      sessionId: "test-session",
+      sessionKey: "test-key",
+      sessionFile: "/tmp/session.json",
+      workspaceDir: "/tmp/workspace",
+      prompt: "hello",
+      timeoutMs: 30000,
+      runId: "run-1",
+    });
+
+    expect(mockedRunEmbeddedAttempt).toHaveBeenCalledTimes(24);
+    expect(mockedCompactDirect).not.toHaveBeenCalled();
+    expect(result.meta.error?.kind).toBe("retry_limit");
+    expect(result.payloads?.[0]?.isError).toBe(true);
+  });
 });

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

@@ -102,6 +102,9 @@ function createCompactionDiagId(): string {
   return `ovf-${Date.now().toString(36)}-${Math.random().toString(36).slice(2, 8)}`;
 }
 
+// Defensive guard for the outer run loop across all retry branches.
+const MAX_RUN_RETRY_ITERATIONS = 24;
+
 const hasUsageValues = (
   usage: ReturnType<typeof normalizeUsage>,
 ): usage is NonNullable<ReturnType<typeof normalizeUsage>> =>
@@ -475,13 +478,42 @@ export async function runEmbeddedPiAgent(
       }
 
       const MAX_OVERFLOW_COMPACTION_ATTEMPTS = 3;
+      const MAX_RUN_LOOP_ITERATIONS = MAX_RUN_RETRY_ITERATIONS;
       let overflowCompactionAttempts = 0;
       let toolResultTruncationAttempted = false;
       const usageAccumulator = createUsageAccumulator();
       let lastRunPromptUsage: ReturnType<typeof normalizeUsage> | undefined;
       let autoCompactionCount = 0;
+      let runLoopIterations = 0;
       try {
         while (true) {
+          if (runLoopIterations >= MAX_RUN_LOOP_ITERATIONS) {
+            const message = `Exceeded retry limit after ${runLoopIterations} attempts.`;
+            log.error(
+              `[run-retry-limit] sessionKey=${params.sessionKey ?? params.sessionId} ` +
+                `provider=${provider}/${modelId} attempts=${runLoopIterations}`,
+            );
+            return {
+              payloads: [
+                {
+                  text:
+                    "Request failed after repeated internal retries. " +
+                    "Please try again, or use /new to start a fresh session.",
+                  isError: true,
+                },
+              ],
+              meta: {
+                durationMs: Date.now() - started,
+                agentMeta: {
+                  sessionId: params.sessionId,
+                  provider,
+                  model: model.id,
+                },
+                error: { kind: "retry_limit", message },
+              },
+            };
+          }
+          runLoopIterations += 1;
           attemptedThinking.add(thinkLevel);
           await fs.mkdir(resolvedWorkspace, { recursive: true });
 

src/agents/pi-embedded-runner/types.ts

@@ -36,7 +36,12 @@ export type EmbeddedPiRunMeta = {
   aborted?: boolean;
   systemPromptReport?: SessionSystemPromptReport;
   error?: {
-    kind: "context_overflow" | "compaction_failure" | "role_ordering" | "image_size";
+    kind:
+      | "context_overflow"
+      | "compaction_failure"
+      | "role_ordering"
+      | "image_size"
+      | "retry_limit";
     message: string;
   };
   /** Stop reason for the agent run (e.g., "completed", "tool_calls"). */