refactor delegation system, add PR summary comments, and improve code quality (#334)

* refactor delegation system and add PR summary comments

Delegation system:
- replace mode-based delegation with select_mode → delegate two-step flow
- orchestrator crafts self-contained subagent prompts (clean context — no system/repo/event instructions leak)
- add role-based tool filtering via FastMCP authenticate hook (?role=subagent hides orchestrator-only tools)
- add select_mode tool for orchestrator guidance per mode
- add ask_question tool for lightweight research subagents
- extract shared subagent lifecycle into subagent.ts (create, complete, stdout, instructions)
- route set_output to per-subagent state when activeSubagentId is set
- track per-subagent state (SubagentState Map) replacing boolean delegationActive flag
- capture and aggregate AgentUsage across all agents (claude, codex, gemini, opencode)
- write usage summary table to GitHub job summary
- block built-in subagent spawning (Task for Claude, Task(*) for Cursor)
- increase activity timeout from 60s to 300s (subagent thinking phases)
- fix gh CLI misguidance in system prompt — explicitly forbid usage

PR summary comments:
- add prSummaryComment trigger (DB schema + migrations + Zod + UI toggle)
- dispatch mini-effort summary job alongside PR review on pr.created
- add update_pull_request_body MCP tool
- add defaultEffort option to webhook dispatch

Hardening:
- rewrite delegate/selectMode tests with simulated state management
- add toolFiltering.test.ts for role extraction, canAccess, set_output routing
- remove non-null assertions for PULLFROG_TEMP_DIR (proper error throws)
- use fetchWithRetry for direct tarball downloads
- DRY fix for rate limit check in test runner

Co-authored-by: Cursor <cursoragent@cursor.com>

* fix: add type keyword to Effort import in handleWebhook.ts

Co-authored-by: Cursor <cursoragent@cursor.com>

* clean up delegation system, improve code quality across the codebase

- simplify delegate tool to instructions + effort params with subagent lifecycle in subagent.ts
- add select_mode and ask_question orchestrator-only tools with canAccess filtering
- replace delegate.test.ts/selectMode.test.ts with toolFiltering.test.ts (live MCP integration)
- add set_output routing for subagent context and AgentUsage tracking across all agents
- add PR summary comment trigger (schema, UI, webhook dispatch with silent flag)
- add update_pull_request_body MCP tool
- fix changed-agents.sh to always include claude canary for non-agent action changes
- fix cursor pagination bug in getSelectedInstallationReposPage
- remove destructuring patterns, inline type definitions, and unsafe type casts
- replace non-null assertions with explicit checks in install.ts
- convert multi-param functions to single param objects (postCleanup, runActionLocal, etc.)
- use isHttpError helper in API routes instead of catch-any patterns
- add adhoc test fixtures for delegation scenarios (context isolation, error handling, synthesis, etc.)

Co-authored-by: Cursor <cursoragent@cursor.com>

* no subagent mutation, one mcp per subagent

* address review feedback: parallel-safe usage tracking, subagent isolation, minor improvements

* fix subagent state isolation: replace Object.freeze with shallow copy

Object.freeze throws TypeErrors when subagent tools (checkout_pr,
report_progress) write scalar properties to toolState. A shallow copy
achieves the same isolation for scalar fields while allowing tools to
work normally. Shared references (subagents Map, usageEntries array)
remain shared for coordination.

---------

Co-authored-by: Cursor <cursoragent@cursor.com>
Co-authored-by: pullfrog[bot] <226033991+pullfrog[bot]@users.noreply.github.com>

test/adhoc/delegateErrorHandling.ts

@@ -0,0 +1,58 @@
+import type { AgentResult, TestRunnerOptions, ValidationCheck } from "../utils.ts";
+import { defineFixture, getAgentOutput, getStructuredOutput } from "../utils.ts";
+
+/**
+ * delegate-error-handling — orchestrator delegates a task that will fail,
+ * then must handle the failure gracefully and report it.
+ *
+ * the subagent is told to read a file that doesn't exist, which will cause
+ * file_read to return an error. the orchestrator should detect the subagent
+ * failure (via the delegate tool's return value) and report it clearly.
+ *
+ * tests error propagation through the delegation system and the orchestrator's
+ * ability to reason about failure modes rather than blindly forwarding results.
+ */
+
+const fixture = defineFixture(
+  {
+    prompt: `You are an orchestrator. This test validates error handling.
+
+1. Select Plan mode via select_mode.
+2. Delegate to a subagent with mini effort. Subagent instructions:
+   "Use gh_pullfrog/file_read to read the file 'this-file-does-not-exist-anywhere.xyz'. Report what you find by calling gh_pullfrog/set_output with the file content. If the file cannot be read, call gh_pullfrog/set_output with 'FILE_NOT_FOUND'."
+3. After the delegation completes, examine the result. The subagent should have reported FILE_NOT_FOUND or an error.
+4. Call set_output with EXACTLY: "ERROR_HANDLED=true,REASON=<brief description of what went wrong>"
+
+If the delegation failed entirely (subagent crashed), still call set_output with "ERROR_HANDLED=true,REASON=delegation_failed".
+
+The point of this test is that you handle the error gracefully and report it — not that you succeed at reading the file.`,
+    effort: "auto",
+    timeout: "8m",
+  },
+  { localOnly: true }
+);
+
+function validator(result: AgentResult): ValidationCheck[] {
+  const output = getStructuredOutput(result);
+  const agentOutput = getAgentOutput(result);
+
+  const setOutputCalled = output !== null;
+  const errorHandled = setOutputCalled && /ERROR_HANDLED=true/i.test(output ?? "");
+  const hasReason = setOutputCalled && /REASON=\S+/i.test(output ?? "");
+  const delegationOccurred = /» delegating subagent=/i.test(agentOutput);
+
+  return [
+    { name: "set_output", passed: setOutputCalled },
+    { name: "error_handled", passed: errorHandled },
+    { name: "reason_provided", passed: hasReason },
+    { name: "delegation_occurred", passed: delegationOccurred },
+  ];
+}
+
+export const test: TestRunnerOptions = {
+  name: "delegate-error-handling",
+  fixture,
+  validator,
+  env: { GITHUB_REPOSITORY: "pullfrog/test-repo" },
+  tags: ["adhoc"],
+};