feat: inject dependency results into cascade prompts and forward model option by heyhuynhgiabuu · Pull Request #7 · tintinweb/pi-tasks

heyhuynhgiabuu · 2026-03-25T05:07:53Z

Summary

Per issue discussion, I narrowed this PR to keep only the changes that are useful in a clean upstream environment.

The earlier RPC fallback work was solving problems caused by my local multi-handler setup (competing subagent packages + custom bridge), not by pi-tasks itself, so that part has been removed.

Changes kept

1. Cascade data flow

buildTaskPrompt() now injects completed dependency results into cascaded agent prompts.

This helps dependent tasks consume prerequisite outputs directly without needing to call TaskGet.

Behavior:

Includes a ## Prerequisite task results section when blocked-by tasks have metadata.result
Caps each dependency result at 4KB
Adds a truncation note pointing users to TaskGet for full output

2. Model forwarding

Passes model from TaskExecute params / cascadeConfig through to:

direct TaskExecute spawns
auto-cascaded spawns

This makes model selection consistent for both manually launched and cascaded task executions.

Tests

Added integration coverage for:

injected prerequisite result in cascaded prompt
truncation behavior for long dependency output
graceful behavior when dependency has no stored result

Verification

npx vitest run → 148 passing tests
npx tsc --noEmit → passes

Copilot

Pull request overview

This PR addresses subagent RPC robustness and task-execution ergonomics in pi-tasks, primarily to fix Issue #6 (spawn failures due to RPC envelope mismatches and ping handling), and to improve cascading execution by forwarding prerequisite outputs and model overrides.

Changes:

Make rpcCall() accept both { success, data } envelopes and legacy bare payload replies.
Improve checkSubagentsVersion() by ignoring malformed ping replies and debouncing concurrent checks.
Enhance cascade execution by injecting dependency results into prompts and forwarding model to spawned subagents.

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Copilot · 2026-03-25T05:12:10Z

src/index.ts

+      if (!subagentsAvailable) {
        pendingWarning =
-          "@tintinweb/pi-subagents is outdated — please update for task execution support.";
-      } else if (remoteVersion > PROTOCOL_VERSION) {
+          "@tintinweb/pi-subagents did not respond with a compatible RPC envelope. " +
+          "Ensure the extension is loaded and up to date.";
+      }


The timeout warning text no longer matches the existing behavior/tests for legacy handlers that reply with {} (no version). Current tests expect a warning mentioning that pi-subagents is outdated, but this now sets a different message on timeout. Either preserve the previous wording for the legacy/no-version case or update the test expectations + any user-facing docs accordingly.

Copilot · 2026-03-25T05:12:10Z

src/index.ts

@@ -160,8 +184,32 @@ export default function (pi: ExtensionAPI) {
  pi.events.on("subagents:ready", () => checkSubagentsVersion());

  /** Build a prompt for a task being executed by a subagent. */


There are two consecutive JSDoc headers for buildTaskPrompt (the old single-line one plus the new multi-line one). Please remove the duplicate so the documentation isn’t repeated in generated docs / editor hovers.

Suggested change

/** Build a prompt for a task being executed by a subagent. */

Copilot · 2026-03-25T05:12:11Z

src/index.ts

+    // Inject completed dependency results so cascaded agents have full context
+    if (task.blockedBy && task.blockedBy.length > 0) {
+      const depResults: string[] = [];
+      for (const depId of task.blockedBy) {
+        const dep = store.get(depId);
+        if (dep?.metadata?.result) {
+          const result = dep.metadata.result.length > 4000
+            ? dep.metadata.result.slice(0, 4000) + "\n\n[... truncated — use TaskGet for full output]"
+            : dep.metadata.result;
+          depResults.push(`### Task #${depId}: ${dep.subject}\n${result}`);
+        }
+      }
+      if (depResults.length > 0) {
+        prompt += `\n\n## Prerequisite task results\n\n${depResults.join("\n\n")}`;
+      }


New behavior here (injecting prerequisite results into prompts) isn’t covered by the existing integration tests. Please add a test that completes a dependency task with a metadata.result and verifies the cascaded spawn prompt includes the injected prerequisite section (and truncation behavior for long results).

Copilot · 2026-03-25T05:12:11Z

src/index.ts

+    if (versionCheckInFlight) return;
+    versionCheckInFlight = true;
    const requestId = randomUUID();
-    const timer = setTimeout(() => { unsub(); }, 5_000);
-    const unsub = pi.events.on(`subagents:rpc:ping:reply:${requestId}`, (raw: unknown) => {
-      unsub(); clearTimeout(timer);
-      const remoteVersion = (raw as any)?.data?.version as number | undefined;
-      if (remoteVersion === undefined) {
+    const channel = `subagents:rpc:ping:reply:${requestId}`;
+    const timer = setTimeout(() => {
+      unsub();
+      versionCheckInFlight = false;
+      if (!subagentsAvailable) {
        pendingWarning =
-          "@tintinweb/pi-subagents is outdated — please update for task execution support.";
-      } else if (remoteVersion > PROTOCOL_VERSION) {
+          "@tintinweb/pi-subagents did not respond with a compatible RPC envelope. " +
+          "Ensure the extension is loaded and up to date.";
+      }
+    }, 5_000);


versionCheckInFlight prevents subagents:ready from triggering a new ping if an earlier ping is already in-flight (e.g., extension loads after init ping was sent but before the 5s timeout). In that case the ready event is effectively dropped and subagentsAvailable can stay false until another ready event happens. Consider queueing a follow-up check (e.g., versionCheckQueued flag) or restarting the ping when subagents:ready arrives during an in-flight check.

heyhuynhgiabuu · 2026-03-25T07:26:26Z

please help me double check it @tintinweb. thanks

…l option - Inject completed dependency results (up to 4KB per dep) into buildTaskPrompt - Forward model option to direct spawn and auto-cascade spawn calls - Add integration tests covering injected prerequisite context and truncation All tests pass.

heyhuynhgiabuu · 2026-03-25T11:17:13Z

Thanks — I reviewed your issue comment and narrowed the PR accordingly.

You were right: the RPC failure was caused by my local environment (multiple handlers / custom bridge), not by pi-tasks itself. I removed the legacy RPC fallback and version-check changes from this PR.

The PR now only contains two feature additions that should be useful independently in a clean upstream setup:

Cascade data flow — inject completed dependency results into cascaded agent prompts
Model forwarding — pass model through direct + cascaded spawns

I also kept targeted integration tests for the cascade prompt behavior.

Current verification:

vitest run ✅ (148 passing)
tsc --noEmit ✅

Sorry again for the initial misattribution.

Copilot AI review requested due to automatic review settings March 25, 2026 05:07

Copilot started reviewing on behalf of heyhuynhgiabuu March 25, 2026 05:08 View session

Copilot AI reviewed Mar 25, 2026

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heyhuynhgiabuu force-pushed the fix/rpc-compatibility-and-cascade-improvements branch from a47d534 to c8e75b0 Compare March 25, 2026 11:16

heyhuynhgiabuu changed the title ~~fix: RPC backward compatibility, ping resilience, cascade data flow, and model forwarding~~ feat: inject dependency results into cascade prompts and forward model option Mar 25, 2026

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heyhuynhgiabuu commented Mar 25, 2026 •

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		@@ -160,8 +184,32 @@ export default function (pi: ExtensionAPI) {
		pi.events.on("subagents:ready", () => checkSubagentsVersion());

		/** Build a prompt for a task being executed by a subagent. */

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heyhuynhgiabuu commented Mar 25, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Summary

Changes kept

1. Cascade data flow

2. Model forwarding

Tests

Verification

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Pull request overview

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heyhuynhgiabuu commented Mar 25, 2026

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heyhuynhgiabuu commented Mar 25, 2026 •

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