U9: Document agent and editorial safety guidance

[breadback00-dev]

What is the work

Create app-owned guidance for the agent intake lane and editorial safety rules around Bristol/local-media event content.

Planned areas:

• docs/agent-guidance/events-roundup-intake.md
• docs/agent-guidance/editorial-safety.md
• README.md

Why does it matter

The app will use agent behavior for intake, but local event details are factual and time-sensitive. Guidance needs to be product-owned and reviewable rather than hidden in one-off prompts.

What does done mean

• Intake guidance documents how to parse Events Roundup content.
• Editorial safety guidance covers ambiguity, factual caution, missing fields, source URLs, Bristol/local tone, and slide constraints.
• README points future contributors to the guidance.
• Guidance is clear that editor review remains required.

Acceptance criteria

• Events Roundup intake guidance exists.
• Editorial safety guidance exists.
• Guidance covers ambiguous facts, missing fields, source preservation, and no silent invention.
• README links to or describes the guidance.
• Guidance does not create a Codex skill file unless a later plan explicitly chooses that mechanism.

Blockers

• Blocked by U4: Build agent intake guidance and parser adapter #4.

What can make this fail

• Agent rules remain implicit in implementation prompts.
• Guidance describes final publishing behavior rather than review-first intake.
• The docs overfit to one sample event list and fail to generalize.
• The repo accidentally adds a Codex skill when app-owned guidance is enough.

How should Codex verify it

• Read the guidance docs for alignment with the requirements and plan.
• Confirm guidance is referenced from README or contributor-facing docs.
• No automated tests required unless implementation imports the guidance directly.
• Check git status for duplicate or empty docs.