docs: add TODO.md with custodian integration notes

Documents C-17 git push warning, AGENTS.md as primary instruction file,
active workplan pointer, and custodian tooling improvements made during
onboarding.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

TODO.md

@@ -0,0 +1,76 @@
+# TODO — Custodian Integration Notes
+
+These notes are for the Codex agent working in this repository. They document the
+current state of the Custodian State Hub integration and what to be aware of.
+
+---
+
+## Git Push Credentials (C-17 Warning)
+
+The Custodian consistency checker warns when local commits have not been pushed to
+the remote. The onboarding commit (AGENTS.md, SCOPE.md, ADR-001 workplans) is
+currently unpushed because Gitea HTTP credentials are not configured in this
+environment.
+
+This does not block normal work, but the checker will warn at each run.
+
+To resolve, either configure HTTP credentials:
+
+```bash
+git config credential.helper store
+git push   # prompts once, then stores
+```
+
+Or switch the remote to SSH (if an SSH key is registered on Gitea):
+
+```bash
+git remote set-url origin git@92.205.130.254:coulomb/repo-registry.git
+git push
+```
+
+Until resolved, the consistency checker will log C-17 and skip file write-backs.
+Task statuses you update in workplan files will still be visible locally; they will
+sync to the hub DB once the push succeeds.
+
+---
+
+## AGENTS.md
+
+`AGENTS.md` at the repo root is your primary instruction file for interacting with
+the Custodian State Hub. Read it at the start of each session. It documents:
+
+- State Hub HTTP API endpoints (orient, inbox, progress logging)
+- Session protocol (start / during / close)
+- Workplan file convention (ADR-001 format)
+- How to create new workplans and notify the hub
+
+---
+
+## Active Workplan
+
+`workplans/RREG-WP-0002-production-hardening.md` is the current active workplan.
+Six tasks remain open (T01–T06). Start with T01 (P0: Update Safety and Change Review)
+as the highest-priority item.
+
+---
+
+## Custodian Tooling Improvements (2026-04-26)
+
+The following improvements were made to the Custodian registration tooling as a
+result of onboarding this repository as the first Codex-based repo:
+
+1. **`register_project.sh --codex` flag** — new flag skips MCP registration check
+   (Claude Code-specific) and generates `AGENTS.md` from an HTTP-API-based template
+   instead of `CLAUDE.md` and `.claude/rules/`. Future Codex repos can use:
+   ```bash
+   cd ~/the-custodian/state-hub
+   make register-codex-project DOMAIN=<domain> PROJECT_PATH=/path/to/repo
+   ```
+
+2. **`agents-codex.template`** — new parameterised template in
+   `state-hub/scripts/project_rules/` that produces the HTTP REST session protocol
+   for Codex agents (this file was used to generate `AGENTS.md` in this repo).
+
+These changes are committed in `the-custodian`. If the tooling needs further
+refinement based on how Codex works with this integration, note it here and the
+custodian operator will update the templates.