Add README

README.md

@@ -0,0 +1,131 @@
+# pi-perplexity
+
+A [pi](https://github.com/nickarrow/pi-coding-agent) extension that provides web search via a Perplexity Pro/Max subscription. Uses your existing subscription — no API credits consumed.
+
+## Installation
+
+```bash
+pi install pi-perplexity
+```
+
+## Usage
+
+Once installed, the agent gains a `perplexity_search` tool it can call automatically when it needs to look something up. You can also trigger a search by asking the agent to search for something.
+
+### Tool Parameters
+
+| Parameter | Type | Required | Description |
+|-----------|------|----------|-------------|
+| `query` | string | yes | Search query |
+| `recency` | string | no | Filter by age: `hour`, `day`, `week`, `month`, `year` |
+| `limit` | number | no | Max sources to return (1–50) |
+
+### Slash Command
+
+```
+/perplexity-login            # Authenticate and save token
+/perplexity-login --force    # Clear cached token and re-authenticate
+```
+
+## Authentication
+
+The extension tries two auth methods in order:
+
+1. **macOS Desktop App** (automatic) — Borrows the JWT from the Perplexity macOS app if installed and signed in. Zero interaction required.
+
+2. **Email OTP** (interactive fallback) — Prompts for your Perplexity email, sends a one-time code, and prompts for the code.
+
+The token is cached at `~/.config/pi-perplexity/auth.json` (permissions `0600`). On HTTP 401/403, the cached token is automatically cleared so the next search re-authenticates.
+
+### Environment Variables
+
+| Variable | Description |
+|----------|-------------|
+| `PI_AUTH_NO_BORROW=1` | Skip macOS desktop app token extraction |
+| `PI_PERPLEXITY_EMAIL` | Email for OTP auth (skips interactive prompt) |
+| `PI_PERPLEXITY_OTP` | OTP code for non-interactive auth |
+
+## How It Works
+
+The extension calls Perplexity's internal SSE endpoint (`perplexity_ask`) with your subscription credentials. Responses stream as incremental events that are merged into a final result containing an answer and sources.
+
+All queries use `is_incognito: true` — nothing appears in your Perplexity search history.
+
+### Output Format
+
+The tool returns structured text the agent can reason over:
+
+```
+## Answer
+<synthesized answer with inline citations>
+
+## Sources
+3 sources
+[1] Example Article (2d ago)
+    https://example.com/article
+    Brief snippet of the source content...
+
+[2] Another Source (5h ago)
+    https://example.com/other
+    Another snippet preview...
+
+## Meta
+Provider: perplexity (oauth)
+Model: pplx_pro_upgraded
+```
+
+## Development
+
+### Prerequisites
+
+- [Bun](https://bun.sh) runtime
+- pi coding agent (`@mariozechner/pi-coding-agent`)
+
+### Commands
+
+```bash
+bun install             # Install dev dependencies
+bun test                # Run tests (29 tests across 5 files)
+bunx tsc --noEmit       # Type check
+```
+
+### Project Structure
+
+```
+src/
+  index.ts              # Extension entry — registers tool and commands
+  auth/
+    login.ts            # macOS app extraction + email OTP flow
+    storage.ts          # Token persistence (~/.config/pi-perplexity/auth.json)
+  commands/
+    login.ts            # /perplexity-login slash command
+  search/
+    types.ts            # Type definitions (StreamEvent, SearchResult, errors)
+    client.ts           # HTTP POST to SSE endpoint, event merging, result extraction
+    stream.ts           # SSE line parser + incremental event merging
+    format.ts           # SearchResult → LLM-readable text output
+  render/
+    call.ts             # TUI component for tool call display
+    result.ts           # TUI component for tool result display
+    util.ts             # Shared render utilities
+```
+
+### Zero Runtime Dependencies
+
+This extension has **no npm dependencies**. Everything uses platform globals:
+
+- `fetch` — HTTP requests
+- `crypto.randomUUID()` — request IDs
+- `ReadableStream` — SSE parsing
+- `Intl.DateTimeFormat` — timezone detection
+
+Only peer dependencies (`@sinclair/typebox`, `@mariozechner/pi-tui`, `@mariozechner/pi-ai`) are used, provided by pi at runtime.
+
+## Requirements
+
+- Perplexity **Pro** or **Max** subscription
+- macOS (for desktop app token extraction) or interactive terminal (for email OTP)
+
+## License
+
+Private — not published.