docs: Add Bird CLI integration design

Adds design doc for integrating Bird CLI as an alternative X/Twitter
search source. Bird uses browser cookies (free, no API key) and
provides direct GraphQL access to X.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docs/plans/2026-02-03-bird-cli-integration-design.md

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+# Bird CLI Integration Design
+
+**Date:** 2026-02-03
+**Status:** Approved
+
+## Overview
+
+Add Bird CLI as an alternative X/Twitter search source for the last30days skill. Bird uses browser cookie authentication (free, no API key) and provides direct access to X's GraphQL API.
+
+## Goals
+
+- Provide free X search without requiring xAI API key
+- Seamless fallback: Bird → xAI → WebSearch
+- Interactive onboarding for users without Bird installed
+- Output parity with existing xAI implementation
+
+## Detection & Priority Flow
+
+```
+On startup:
+1. Check: Is Bird installed? (`which bird`)
+   ├─ No → Offer to install: "Bird CLI not found. Install for free X search? (y/n)"
+   │        ├─ Yes → Run `npm install -g @steipete/bird`
+   │        └─ No → Continue to step 2
+   │
+   └─ Yes → Check: Is Bird authenticated? (`bird whoami`)
+            ├─ Success → Use Bird for X searches
+            └─ Fail → Show: "Bird auth failed. Run `bird check` to diagnose."
+                      Continue to step 2
+
+2. Fall back to xAI if XAI_API_KEY exists
+3. Fall back to WebSearch if nothing else available
+```
+
+**Priority order:** Bird → xAI → WebSearch
+
+## New Module: `scripts/lib/bird_x.py`
+
+### Functions
+
+- `is_bird_installed()` → checks `which bird`, returns bool
+- `is_bird_authenticated()` → runs `bird whoami`, returns username or None
+- `install_bird()` → runs `npm install -g @steipete/bird`, returns success bool
+- `search_x(topic, from_date, to_date, depth)` → runs `bird search` with JSON output
+- `parse_bird_response(json)` → converts to same format as `xai_x.parse_x_response()`
+
+### Search Command
+
+```bash
+bird search "Claude Code skills" --since 2026-01-04 -n 30 --json
+```
+
+- `--since` filters to last 30 days
+- `-n 30` controls result count (maps to depth: quick=12, default=30, deep=60)
+- `--json` gives machine-readable output
+
+### Output Mapping
+
+| Bird field | Our field |
+|------------|-----------|
+| `text` | `text` |
+| `permanent_url` | `url` |
+| `user.screen_name` | `author_handle` |
+| `created_at` | `date` (parse to YYYY-MM-DD) |
+| `like_count` | `engagement.likes` |
+| `retweet_count` | `engagement.reposts` |
+| `reply_count` | `engagement.replies` |
+| `quote_count` | `engagement.quotes` |
+
+Relevance: Default to 0.7, let `score.py` re-rank based on engagement.
+
+## Modified Files
+
+| File | Change |
+|------|--------|
+| `env.py` | Add `get_x_source()` → returns `'bird'`, `'xai'`, or `None` |
+| `last30days.py` | Check Bird availability with interactive install prompt before research |
+| `last30days.py` | In `_search_x()`, dispatch to `bird_x` or `xai_x` based on source |
+| `ui.py` | Add `prompt_bird_install()` and `show_bird_auth_help()` |
+
+## Unchanged Files
+
+- `normalize.py` - Bird output matches xAI format after parsing
+- `score.py` - Same scoring logic applies
+- `dedupe.py` - Same deduplication logic
+- `render.py` - X results labeled as "X" regardless of backend
+
+## Error Handling
+
+| Scenario | Behavior |
+|----------|----------|
+| Bird installed but no browser cookies | Show `bird check` guidance, fall back to xAI |
+| Bird search returns 0 results | Retry with simplified query (same as xAI logic) |
+| Bird search times out | Fall back to xAI if available, else WebSearch |
+| npm not installed (can't install Bird) | Skip Bird, continue with xAI/WebSearch |
+| User declines Bird install | Remember for session, don't ask again |
+
+**Timeout:** 30 seconds for Bird commands
+
+## Output Labels
+
+Results labeled as "X" regardless of whether Bird or xAI was used. Users care about the data, not the backend.