Plan Canvas

---
name: plan-canvas
description: Open plans and HTML artifacts in a local browser canvas where the human annotates elements, chats, and approves or requests changes without leaving the page. Use when presenting a plan for review, or when feedback like "move this, change that" is easier pointed at than typed.
metadata:
  origin: ECC
version: "1.0.0"
---

# Plan Canvas

Review loop for plans and visual artifacts: you write the artifact, the human
reviews it in the browser — annotating the exact element they mean, chatting,
and delivering an **Approve plan / Request changes** verdict — while you block
on a single CLI call that returns their feedback as JSON.

Inspired by [lavish-axi](https://github.com/kunchenguid/lavish-axi); rebuilt
ECC-native around the `/plan` confirmation gate, with zero dependencies.

## When to Use

- You just wrote a plan artifact (`.claude/plans/*.plan.md` from `/plan`) and
  need the CONFIRM/approve decision — the canvas verdict replaces a typed
  "yes/proceed".
- The user should *point at* what to change: reviewing designs, comparisons,
  reports, or any local `.md` / `.html` artifact.
- The user asks for `/plan-canvas`, a visual review, or "open it in the browser".

Do NOT use for: code review of diffs (`/code-review`), running web apps, or
remote URLs. The canvas serves local artifact files only.

## How It Works

Invoke the CLI as `ecc-plan-canvas` — the bin shipped by the `ecc-universal`
package (on PATH after a global/plugin install; `node "$CLAUDE_PLUGIN_ROOT/scripts/plan-canvas.js"`
also works for plugin installs). Run it from the project you are reviewing in;
it works from any working directory. It manages a detached loopback server
(`127.0.0.1:4517`) shared by all sessions, keyed by artifact path — no session
ids to track.

The workflow is a plain CLI-plus-JSON loop, so it is model- and harness-agnostic:
any agent that can run a shell command and read stdout drives it the same way
(Claude Code, Codex, Cursor, Gemini, OpenCode, Copilot). Trigger it however your
harness surfaces skills — e.g. `/plan-canvas` in Claude Code, `$plan-canvas` in
Codex — or just run the `ecc-plan-canvas` commands directly.

```bash
# 1. Open the artifact in the user's browser (returns immediately)
ecc-plan-canvas open .claude/plans/feature.plan.md

# 2. Block until the human responds. Leave running; re-run if interrupted:
#    queued feedback is never lost.
ecc-plan-canvas await .claude/plans/feature.plan.md
```

### Stay listening, or the human talks to an empty chair

Feedback only reaches you while an `await` is actually parked on the session.
If your turn ends with nothing listening, the message sits in the queue and,
from the human's side of the glass, sending appears to do nothing at all.

So **run `await` as a background task** when your harness supports one (in
Claude Code, a Bash call with `run_in_background: true`). It exits the moment
feedback arrives and the harness hands you the JSON, which keeps the loop alive
across turns instead of dying with the foreground call. A foreground `await`
works too, but only until the harness time-limits it.