Ce Proof

# Proof - Collaborative Markdown Editor

Proof is a collaborative document editor for humans and agents. It supports two modes:

1. **Web API** - Create and edit shared documents via HTTP (no install needed)
2. **Local Bridge** - Drive the macOS Proof app via localhost:9847

## Identity and Attribution

Every write to a Proof doc must be attributed. Two fields carry the agent's identity:

- **Machine ID (`by` on every op, `X-Agent-Id` header):** `ai:compound-engineering` — stable, lowercase-hyphenated, machine-parseable. Appears in marks, events, and the API response.
- **Display name (`name` on `POST /presence`):** `Compound Engineering` — human-readable, shown in Proof's presence chips and comment-author badges.

Set the display name once per doc session by posting to presence with the `X-Agent-Id` header; Proof binds the name to that agent ID for the session. These values are the defaults for any caller of this skill; callers running HITL review (`references/hitl-review.md`) may pass a different `identity` pair if a distinct sub-agent should own the doc. Do not use `ai:compound` or other ad-hoc variants — identity stays uniform unless a caller explicitly overrides it.

## Human-in-the-Loop Review Mode

Human-in-the-loop iteration over an existing local markdown file: upload to Proof, let the user annotate in Proof's web UI, ingest feedback as in-thread replies and tracked edits, and sync the final doc back to disk. Two entry points, identical mechanics — load `references/hitl-review.md` for the full loop spec (invocation contract, mark classification, idempotent ingest passes, exception-based terminal reporting, end-sync atomic write) in either case:

- **Direct user request** — a bare user phrase naming a local markdown file and asking to iterate collaboratively via Proof: "share this to proof so we can iterate", "iterate with proof on this doc", "HITL this file with me", "let's get feedback on this in proof", "open this in proof editor so I can review". The file is whichever markdown the user just created, edited, or referenced; if ambiguous, ask which file. This is a first-class entry point — do not require an upstream caller.
- **Upstream skill handoff** — `ce-brainstorm`, `ce-ideate`, or `ce-plan` finishes a draft and hands it off for human review before the next phase, passing the file path and title explicitly.

## Web API (Primary for Sharing)

### Create a Shared Document

No authentication required. Returns a shareable URL with access token.

```bash
curl -X POST https://www.proofeditor.ai/share/markdown \
  -H "Content-Type: application/json" \
  -d '{"title":"My Doc","markdown":"# Hello\n\nContent here."}'
```

**Response format:**
```json
{
  "slug": "abc123",
  "tokenUrl": "https://www.proofeditor.ai/d/abc123?token=xxx",
  "accessToken": "xxx",
  "ownerSecret": "yyy",
  "_links": {
    "state": "https://www.proofeditor.ai/api/agent/abc123/state",
    "ops": "https://www.proofeditor.ai/api/agent/abc123/ops"
  }
}
```

Use the `tokenUrl` as the shareable link. The `_links` give you the exact API paths.

### Read a Shared Document

```bash
curl -s "https://www.proofeditor.ai/api/agent/{slug}/state" \
  -H "x-share-token: <token>"
```

### Edit a Shared Document

All operations go to `POST https://www.proofeditor.ai/api/agent/{slug}/ops`

**Note:** Use the `/api/agent/{slug}/ops` path (from `_links` in create response), NOT `/api/documents/{slug}/ops`.

**Authentication for protected d