feat(cli): --repo, and teach the review skill to find the repository and the PR

packages/cli/src/index.ts

@@ -1,5 +1,7 @@
 import { Command } from 'commander';
 import { createHash } from 'node:crypto';
+import { existsSync, statSync } from 'node:fs';
+import { resolve } from 'node:path';
 import { createRequire } from 'node:module';
 import open from 'open';
 import pc from 'picocolors';
@@ -31,13 +33,35 @@ const pkg = require('../package.json');
 
 const program = new Command();
 
+// Project directories often hold several worktrees as subdirectories, so the repository to
+// review is not always the directory the command was run from. Everything downstream resolves
+// against the working directory, so switching it here is enough.
+function applyRepoOption(repo: unknown): void {
+  if (typeof repo !== 'string' || !repo) {
+    return;
+  }
+
+  const target = resolve(repo);
+  if (!existsSync(target) || !statSync(target).isDirectory()) {
+    console.error(pc.red(`Error: --repo is not a directory: ${repo}`));
+    process.exit(1);
+  }
+
+  process.chdir(target);
+}
+
+program.hook('preAction', (thisCommand) => {
+  applyRepoOption(thisCommand.opts().repo);
+});
+
 program
   .name('diffity')
   .description('GitHub-style git diff viewer in the browser')
   .version(pkg.version)
   .enablePositionalOptions()
   .passThroughOptions()
   .option('--skills-hash', 'Print skills hash and exit', false)
+  .option('--repo <path>', 'Repository to work on, when the current directory is not one')
   .argument('[refs...]', 'Git refs to diff')
   .option('--base <ref>', 'Base ref to compare from (e.g. main, HEAD~3, v1.0.0)')
   .option('--compare <ref>', 'Ref to compare against base (default: working tree)')

packages/skills/diffity-resolve/SKILL.md

@@ -33,7 +33,15 @@ You are reading open review comments and resolving them by making the requested
 ## Prerequisites
 
 1. Check that `{{binary}}` is available: run `which {{binary}}`. If not found, {{install_hint}}.
-2. Check that a review session exists: run `{{binary}} agent list`. If this fails with "No active review session", tell the user to start diffity first (e.g. `{{binary}}` or **{{slash}}diff**).
+2. **Work out which repository to use.** A project directory often holds several worktrees as
+   subdirectories rather than being a repository itself, so the current directory may not be one.
+   - If the current directory is a git repository (`git rev-parse --show-toplevel` succeeds), use it.
+   - Otherwise look one level down for directories containing a `.git` entry. Exactly one → use it.
+     Several → **ask the user which one**, listing them with their current branch, and stop until
+     they answer. Guessing here reviews the wrong branch, which wastes the whole review.
+   - Pass the chosen directory to every `{{binary}}` call as `--repo <path>`, before any positional
+     argument. Do not `cd`.
+3. Check that a review session exists: run `{{binary}} agent list`. If this fails with "No active review session", tell the user to start diffity first (e.g. `{{binary}}` or **{{slash}}diff**).
 
 ## Instructions
 

packages/skills/diffity-review/SKILL.md

@@ -10,7 +10,10 @@ You are reviewing a diff and leaving inline comments using the `{{binary}} agent
 
 ## Arguments
 
-- `ref` (optional): Git ref to review (e.g. `main..feature`, `HEAD~3`). Defaults to working tree changes. When both `ref` and `focus` are provided, use both (e.g. `/diffity-review main..feature security`).
+- `ref` (optional): Git ref to review (e.g. `main..feature`, `HEAD~3`). When both `ref` and `focus` are provided, use both (e.g. `/diffity-review main..feature security`).
+  With no `ref`, review **the pull request for the current branch** if there is one, and the working
+  tree otherwise — see Step 0. "Review my draft PR" with everything committed means the pull
+  request, not the empty set of uncommitted changes.
 - `focus` (optional): Focus the review on a specific area. One of: `security`, `performance`, `naming`, `errors`, `types`, `logic`. If omitted, review everything.
 
 ## CLI Reference
@@ -38,9 +41,35 @@ You are reviewing a diff and leaving inline comments using the `{{binary}} agent
 ## Prerequisites
 
 1. Check that `{{binary}}` is available: run `which {{binary}}`. If not found, {{install_hint}}.
+2. **Work out which repository to use.** A project directory often holds several worktrees as
+   subdirectories rather than being a repository itself, so the current directory may not be one.
+   - If the current directory is a git repository (`git rev-parse --show-toplevel` succeeds), use it.
+   - Otherwise look one level down for directories containing a `.git` entry. Exactly one → use it.
+     Several → **ask the user which one**, listing them with their current branch, and stop until
+     they answer. Guessing here reviews the wrong branch, which wastes the whole review.
+   - Pass the chosen directory to every `{{binary}}` call as `--repo <path>`, before any positional
+     argument. Do not `cd`.
+
 
 ## Instructions
 
+### Step 0: Decide what to review
+
+Only when no `ref` argument was given:
+
+1. Ask GitHub whether the current branch has a pull request:
+   ```
+   gh pr view --json number,url,isDraft,baseRefName
+   ```
+2. If it returns one, **review the pull request**: use its URL as the ref
+   (`{{binary}} --repo <path> --no-open <pr-url>`). diffity pins the diff to the pull request's base
+   commit, so it matches what GitHub shows — a plain working-tree diff on a branch whose work is
+   committed would be empty. A draft counts; that is the usual case for a review before marking it
+   Ready.
+3. If there is no pull request, or `gh` is unavailable, review the working tree as before.
+
+State which one you chose in your first message, so the user can correct you cheaply.
+
 ### Step 1: Ensure diffity is running for the correct ref (without opening browser)
 
 The review needs a running session whose ref matches the requested ref. A ref mismatch causes "file not in current diff" errors when adding comments.

skills/diffity-resolve/SKILL.md

@@ -33,7 +33,15 @@ diffity agent reply <id> --body "<text>"
 ## Prerequisites
 
 1. Check that `diffity` is available: run `which diffity`. If not found, install it with `npm install -g diffity`.
-2. Check that a review session exists: run `diffity agent list`. If this fails with "No active review session", tell the user to start diffity first (e.g. `diffity` or **/diffity-diff**).
+2. **Work out which repository to use.** A project directory often holds several worktrees as
+   subdirectories rather than being a repository itself, so the current directory may not be one.
+   - If the current directory is a git repository (`git rev-parse --show-toplevel` succeeds), use it.
+   - Otherwise look one level down for directories containing a `.git` entry. Exactly one → use it.
+     Several → **ask the user which one**, listing them with their current branch, and stop until
+     they answer. Guessing here reviews the wrong branch, which wastes the whole review.
+   - Pass the chosen directory to every `diffity` call as `--repo <path>`, before any positional
+     argument. Do not `cd`.
+3. Check that a review session exists: run `diffity agent list`. If this fails with "No active review session", tell the user to start diffity first (e.g. `diffity` or **/diffity-diff**).
 
 ## Instructions
 

skills/diffity-review/SKILL.md

@@ -10,7 +10,10 @@ You are reviewing a diff and leaving inline comments using the `diffity agent` C
 
 ## Arguments
 
-- `ref` (optional): Git ref to review (e.g. `main..feature`, `HEAD~3`). Defaults to working tree changes. When both `ref` and `focus` are provided, use both (e.g. `/diffity-review main..feature security`).
+- `ref` (optional): Git ref to review (e.g. `main..feature`, `HEAD~3`). When both `ref` and `focus` are provided, use both (e.g. `/diffity-review main..feature security`).
+  With no `ref`, review **the pull request for the current branch** if there is one, and the working
+  tree otherwise — see Step 0. "Review my draft PR" with everything committed means the pull
+  request, not the empty set of uncommitted changes.
 - `focus` (optional): Focus the review on a specific area. One of: `security`, `performance`, `naming`, `errors`, `types`, `logic`. If omitted, review everything.
 
 ## CLI Reference
@@ -38,9 +41,35 @@ diffity agent tour-done --tour <id>
 ## Prerequisites
 
 1. Check that `diffity` is available: run `which diffity`. If not found, install it with `npm install -g diffity`.
+2. **Work out which repository to use.** A project directory often holds several worktrees as
+   subdirectories rather than being a repository itself, so the current directory may not be one.
+   - If the current directory is a git repository (`git rev-parse --show-toplevel` succeeds), use it.
+   - Otherwise look one level down for directories containing a `.git` entry. Exactly one → use it.
+     Several → **ask the user which one**, listing them with their current branch, and stop until
+     they answer. Guessing here reviews the wrong branch, which wastes the whole review.
+   - Pass the chosen directory to every `diffity` call as `--repo <path>`, before any positional
+     argument. Do not `cd`.
+
 
 ## Instructions
 
+### Step 0: Decide what to review
+
+Only when no `ref` argument was given:
+
+1. Ask GitHub whether the current branch has a pull request:
+   ```
+   gh pr view --json number,url,isDraft,baseRefName
+   ```
+2. If it returns one, **review the pull request**: use its URL as the ref
+   (`diffity --repo <path> --no-open <pr-url>`). diffity pins the diff to the pull request's base
+   commit, so it matches what GitHub shows — a plain working-tree diff on a branch whose work is
+   committed would be empty. A draft counts; that is the usual case for a review before marking it
+   Ready.
+3. If there is no pull request, or `gh` is unavailable, review the working tree as before.
+
+State which one you chose in your first message, so the user can correct you cheaply.
+
 ### Step 1: Ensure diffity is running for the correct ref (without opening browser)
 
 The review needs a running session whose ref matches the requested ref. A ref mismatch causes "file not in current diff" errors when adding comments.