refactor(agents,triggers): extract shared modules to eliminate duplication

[zbigniewsobiecki]

Summary

• Extract ~1,530 lines of duplicated code across 4 agent files and 10 trigger/webhook files into focused shared modules under src/agents/shared/ and src/triggers/shared/
• Net reduction of 436 lines (-1,528 / +1,092) while preserving all existing behavior and test coverage
• All 436 existing tests pass unchanged — no behavioral changes

Agent shared modules (src/agents/shared/)

Module	Replaces	Description
lifecycle.ts	4 × ~155L execution skeleton	Generic executeAgentLifecycle<TContext>() handling logger setup, watchdog, repo init, LLMist client creation, agent loop, and cleanup
builderFactory.ts	4 × ~60L builder chain	createConfiguredBuilder() with full 13-method AgentBuilder chain, AU gadget appending, session state init
syntheticCalls.ts	4 × ~50L injection logic	injectDirectoryListing(), injectContextFiles(), injectAUContext(), injectSyntheticCall()
modelResolution.ts	4 × ~25L config resolution	resolveModelConfig() with configKey support for config sharing
prFormatting.ts	3 × ~15L formatting	formatPRDetails(), formatPRDiff()
repository.ts	4 × ~40L setup	setupRepository() with SetupRepositoryOptions interface

Trigger shared utilities

Module	Replaces	Description
triggers/github/utils.ts	3 × self-auth check, 3 × card validation	isSelfAuthored(), requireTrelloCardId()
triggers/shared/agent-result-handler.ts	2 × ~25L log upload + cost update	handleAgentResultArtifacts() for both webhook handlers

What stays unique per agent

• base.ts: Multi-flow dispatch (Trello/PR/debug), Trello card fetching, prompt builders, status updates, extractPRUrl post-processing
• respond-to-ci.ts: CI log fetching, formatCheckStatus(), pre-flight failed-check verification, acknowledgment comment
• respond-to-review.ts: formatPRComments/Reviews/IssueComments(), review-specific synthetic calls
• review.ts: readPRFileContents() with token limiting, CreatePRReview gadget

Test plan

• npx tsc --noEmit — zero type errors
• npm test — all 436 tests pass (32 test files)
• npm run lint — clean (only 5 pre-existing complexity warnings)
• Pre-commit hooks pass (lint + typecheck + commitlint)
• Pre-push hooks pass (full test suite)

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