Restore TODO.md and move TODO content out of README

TODO.md

@@ -0,0 +1,75 @@
+# Workflow
+
+* branch (from `main`)
+* do the work in Next Step
+* move Next Step to the top of Completed Steps
+* move the top item of Future Steps into Next Step
+* commit (`TODO.md` changes in the same commit as the work)
+* merge to `main` if the branch is not protected, otherwise open a PR
+* push
+
+# Status
+
+pre-1.0. No git tags exist. main (afe88c6) is a working webhook proxy
+with auth, CSRF/SSRF protections, login rate limiting, Slack target,
+policy compliance (#6), and pinned lint tooling (#55). Note: TODO.md was
+deliberately deleted from this repo in f9a9569 (2026-03-01, #6); its
+content was folded into the README TODO section, which this draft
+reconstructs as of 2026-07-06.
+
+# Next Step
+
+Implement automatic event retention cleanup based on retention_days: a
+periodic maintenance job that deletes Events, Deliveries, and
+DeliveryResults older than the parent webhook's retention_days from each
+per-webhook event database. The field exists on the Webhook model and
+the README promises the behavior, but nothing enforces it, so event
+databases currently grow without bound.
+
+# Completed Steps
+
+- 2026-03-25 pin golangci-lint Docker image for linting (#55)
+- 2026-03-18 CSRF middleware detects TLS per-request, fixing login over
+  plain HTTP and behind reverse proxies (#54)
+- 2026-03-17 root path redirects based on auth state (#52)
+- 2026-03-17 CSRF protection, SSRF prevention for HTTP delivery targets
+  with DNS rebinding defense, and per-IP login rate limiting (#42)
+- 2026-03-17 Slack target type for incoming webhook notifications (#47)
+- 2026-03-17 Dockerfile absolute paths and static linking (#49);
+  absolute dev DATA_DIR default and clarified env docs (#46)
+- 2026-03-05 security headers middleware, session regeneration on
+  login, request body size limits (#41)
+- 2026-03-04 tests for delivery, middleware, and session packages
+  (#32); removed globals.Buildarch (#31)
+- 2026-03-04 1.0 MVP merge: Webhook/Entrypoint/Target rename, core
+  delivery engine with bounded worker pool and circuit breaker,
+  parallel fan-out, per-webhook event databases, management UI (#16)
+- 2026-03-01 repo brought to REPO_POLICIES standards; TODO.md folded
+  into README (#6)
+
+# Future Steps
+
+- Manual event redelivery from the web UI (replay is a core promised
+  capability in the README rationale)
+- Delivery status and retry management UI
+- Per-webhook rate limiting in the receiver handler (per-webhook config
+  plus handler enforcement; global limits must not apply to receiver
+  endpoints)
+- Webhook signature verification for GitHub and Stripe HMAC formats
+- API key authentication for programmatic access (APIKey model exists;
+  Bearer token middleware does not)
+- REST API v1
+    - CRUD for webhooks, entrypoints, targets
+    - event viewing and filtering endpoints
+    - event redelivery endpoint
+    - OpenAPI specification
+- Analytics dashboard: success rates, response times, volume
+- Session expiration tuning and a remember-me option
+- Password change and reset flow
+- Later, nice to have
+    - email delivery target type
+    - SNS and S3 delivery targets
+    - data transformations (e.g. webhook to Slack message formatting)
+    - JSONL file delivery with periodic S3 upload
+    - webhook event search and filtering
+    - multi-user with role-based access control