Plan step C4 (docs/upstream-sync/domain-reorg/reorg-build-plan.md, approved
decisions 1-2): split the 2,590-line agent/webapp.py monolith into
agent/webhooks/common.py (shared verify/dispatch helpers), agent/api/app.py
(composition), agent/api/health.py (/health + /webhooks/run-complete), and
per-source {github,linear,slack,jira,confluence}_routes.py. Atlassian
Connect lifecycle + descriptor routes (/connect/*) fold into
confluence_routes.py; webapp.py becomes the upstream-shaped compatibility
shim (from .api.app import app). langgraph.json http.app stays
agent.webapp:app via the shim.
Fork content, upstream layout: linear/slack route files verified
content-identical to upstream 8356eb34 and taken verbatim; github_routes is
upstream + the fork's CI auto-fix trigger wiring; jira/confluence routes are
fork-only, transformed to the same common.X / service.X module-attribute
style. All signature verification (GitHub HMAC, Slack, Linear
timestamp-freshness, verify_jira_secret + opt-in HMAC/timestamp/IP
allowlist, Connect JWT/qsh), token-attribution gating, TID-COLLIDE-01 repo
binding, _is_repo_auto_review_enabled gates, and public-repo org gate move
unchanged.
Handlers rewired from webapp.X to common.X; test monkeypatch sites across
26 files + conftest.py + e2e/harness.py retargeted to
webhook_common/handler/route modules per upstream's pattern. Residual
agent.webapp importers: only the shim, langgraph.json http.app, Makefile
uvicorn target, and docs (doc-path updates land in C7).
Gates: ruff check + format, pytest --co, full unit (1637 passed), full
Playwright E2E vs real langgraph dev (9/9), residual-importer sweep.
