docs: add TROUBLESHOOTING.md with common setup and config fixes

Author: TerminalGravity

README.md

@@ -744,6 +744,16 @@ curl http://localhost:11434/api/embed -d '{"model":"all-minilm","input":"test"}'
 
 ---
 
+## Troubleshooting
+
+Having issues? Check **[TROUBLESHOOTING.md](TROUBLESHOOTING.md)** for solutions to common problems including:
+- LanceDB setup and platform issues
+- Embedding provider configuration
+- `.preflight/` config parsing errors
+- Profile selection guide
+
+---
+
 ## Contributing
 
 This project is young and there's plenty to do. Check the [issues](https://github.com/TerminalGravity/preflight/issues) — several are tagged `good first issue`.

TROUBLESHOOTING.md

@@ -0,0 +1,165 @@
+# Troubleshooting
+
+Common issues and fixes for preflight.
+
+---
+
+## Installation & Setup
+
+### `npx preflight-dev-serve` fails with module errors
+
+**Symptoms:** `ERR_MODULE_NOT_FOUND` or `Cannot find module` when running via npx.
+
+**Fix:** Preflight requires **Node 20+**. Check your version:
+```bash
+node --version
+```
+If you're on Node 18 or below, upgrade via [nvm](https://github.com/nvm-sh/nvm):
+```bash
+nvm install 20
+nvm use 20
+```
+
+### Tools don't appear in Claude Code after `claude mcp add`
+
+**Fix:** Restart Claude Code completely after adding the MCP server. The tool list is loaded at startup.
+
+If tools still don't appear, verify the server starts without errors:
+```bash
+npx preflight-dev-serve
+```
+You should see MCP protocol output (JSON on stdout). If you see errors, check the sections below.
+
+---
+
+## LanceDB & Timeline Search
+
+### `Error: Failed to open LanceDB` or LanceDB crashes on startup
+
+**Symptoms:** Timeline tools (`search_timeline`, `index_sessions`, etc.) fail. Other tools work fine.
+
+**Cause:** LanceDB uses native binaries that may not be available for your platform, or the database directory has permission issues.
+
+**Fixes:**
+1. Make sure `~/.preflight/projects/` is writable:
+   ```bash
+   mkdir -p ~/.preflight/projects
+   ls -la ~/.preflight/
+   ```
+2. If on an unsupported platform, use the **minimal** or **standard** profile (no LanceDB required):
+   ```bash
+   npx preflight-dev
+   # Choose "minimal" or "standard" when prompted
+   ```
+3. Clear corrupted LanceDB data:
+   ```bash
+   rm -rf ~/.preflight/projects/*/timeline.lance
+   ```
+   Then re-index with `index_sessions`.
+
+### Timeline search returns no results
+
+**Cause:** Sessions haven't been indexed yet. Preflight doesn't auto-index — you need to run `index_sessions` first.
+
+**Fix:** In Claude Code, run:
+```
+index my sessions
+```
+Or use the `index_sessions` tool directly. Indexing reads your `~/.claude/projects/` session files.
+
+---
+
+## Embeddings
+
+### `OpenAI API key required for openai embedding provider`
+
+**Cause:** You selected OpenAI embeddings but didn't set the API key.
+
+**Fixes:**
+
+Option A — Set the environment variable when adding the MCP server:
+```bash
+claude mcp add preflight \
+  -e OPENAI_API_KEY=sk-... \
+  -- npx -y preflight-dev-serve
+```
+
+Option B — Switch to local embeddings (no API key needed). Create or edit `~/.preflight/config.json`:
+```json
+{
+  "embedding_provider": "local",
+  "embedding_model": "Xenova/all-MiniLM-L6-v2"
+}
+```
+
+### Local embeddings are slow on first run
+
+**Expected.** The model (~80MB) downloads on first use and is cached afterward. Subsequent runs are fast.
+
+---
+
+## `.preflight/` Config
+
+### `warning - failed to parse .preflight/config.yml`
+
+**Cause:** YAML syntax error in your project's `.preflight/config.yml`.
+
+**Fix:** Validate your YAML:
+```bash
+npx yaml-lint .preflight/config.yml
+```
+Or check for common issues: wrong indentation, tabs instead of spaces, missing colons.
+
+### Config changes not taking effect
+
+**Cause:** Preflight reads config at MCP server startup, not on every tool call.
+
+**Fix:** Restart Claude Code after editing `.preflight/config.yml` or `.preflight/triage.yml`.
+
+---
+
+## Profiles
+
+### Which profile should I use?
+
+| Profile | Tools | Best for |
+|---------|-------|----------|
+| **minimal** | 4 | Try it out, low overhead |
+| **standard** | 16 | Daily use, no vector search needed |
+| **full** | 20 | Power users who want timeline search |
+
+You can change profiles by re-running the setup wizard:
+```bash
+npx preflight-dev
+```
+
+---
+
+## Platform-Specific
+
+### Apple Silicon (M1/M2/M3/M4): LanceDB build fails
+
+LanceDB ships prebuilt binaries for Apple Silicon. If `npm install` fails on the native module:
+```bash
+# Ensure you're using the ARM64 version of Node
+node -p process.arch   # should print "arm64"
+
+# If it prints "x64", reinstall Node natively (not via Rosetta)
+```
+
+### Linux: Permission denied on `~/.preflight/`
+
+```bash
+chmod -R u+rwX ~/.preflight/
+```
+
+---
+
+## Still stuck?
+
+1. Check [open issues](https://github.com/TerminalGravity/preflight/issues) — someone may have hit the same problem
+2. [Open a new issue](https://github.com/TerminalGravity/preflight/issues/new) with:
+   - Your Node version (`node --version`)
+   - Your OS and architecture (`uname -a`)
+   - The full error message
+   - Which profile you selected