feat: add lk docs commands for searching and browsing LiveKit documentation (#774)

* search

* refactor: use official MCP Go SDK, add missing submit-feedback params

Replace hand-rolled MCP streamable HTTP client (~230 lines) with the
official modelcontextprotocol/go-sdk. Also add missing --agent and
--model flags to submit-feedback to match the server's full schema.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* feat: warn when docs MCP server is newer than expected

Check the server's reported version after connecting. If the major or
minor version is newer than what this CLI was built against (currently
1.2.x), print a warning to stderr suggesting the user update lk.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* feat: add hidden --server-url and --vercel-header flags for docs dev

Add hidden flags to `lk docs` for development against staging or preview
deployments of the docs MCP server. Also add a README section documenting
the docs feature and its development options.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* feat: send lk_cli_version and project_id with docs MCP tool calls

Injects lightweight telemetry params into every MCP tool call so the
docs server can track CLI version and optionally the Cloud project ID.
The project ID is resolved silently from the --project flag or default
project config and omitted when no project is configured.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* feat: add request timeout, unit tests, fix hits-per-page default

- Add 30s timeout to all docs MCP requests to prevent hanging if the
  server is unresponsive.
- Remove hardcoded hits-per-page default of 10; let the server default
  to 20 instead.
- Add unit tests for parseMajorMinor, isNotFoundErr, and
  headerTransport.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* feat: add --json flag to docs commands

Adds a --json / -j flag on the docs parent command so all tool-based
subcommands can request JSON output from the MCP server. When set,
sends format: "json" in the tool call arguments.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* feat: switch list-sdks to get_sdks tool, bump expected server to 1.3

Replace the livekit://sdks resource read with the new get_sdks tool
call, which supports all standard params (format, telemetry). Remove
the now-unused callDocsResourceAndPrint helper and encoding/json
import. Bump expectedServerVersion to 1.3.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix: use camelCase for telemetry params (lkCliVersion, projectId)

Match the server-side naming convention.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: bcherry

README.md

@@ -437,6 +437,50 @@ The above simulates 5 concurrent rooms, where each room has:
 Once the specified duration is over (or if the load test is manually stopped), the load test statistics will be displayed in the form of a table.
 
 
+## Browsing documentation
+
+The CLI includes a built-in `lk docs` command that lets you search and browse the LiveKit documentation directly from the terminal. It's powered by the [LiveKit docs MCP server](https://docs.livekit.io/mcp) using the official [MCP Go SDK](https://github.com/modelcontextprotocol/go-sdk).
+
+```shell
+# Get a complete overview of the docs site
+lk docs overview
+
+# Search the docs
+lk docs search "voice agents"
+
+# Fetch a specific page as markdown
+lk docs get-page /agents/start/voice-ai-quickstart
+
+# Search code across LiveKit GitHub repos
+lk docs code-search "class AgentSession" --repo livekit/agents
+
+# Get recent releases for an SDK
+lk docs changelog pypi:livekit-agents
+
+# List all LiveKit SDKs
+lk docs list-sdks
+
+# Submit feedback on the docs
+lk docs submit-feedback --page /agents/build/tools "Missing info about error handling"
+```
+
+Run `lk docs --help` for full details on each subcommand.
+
+### Development options
+
+For development against staging or preview deployments of the docs MCP server, two hidden flags are available on the `lk docs` command:
+
+-   `--server-url URL`: Override the MCP server endpoint (default: `https://docs.livekit.io/mcp/`)
+-   `--vercel-header VALUE`: Set the `x-vercel-protection-bypass` header, required for accessing private Vercel preview deployments
+
+```shell
+# Use a staging server
+lk docs --server-url https://docs-staging.example.com/mcp/ search "agents"
+
+# Access a private Vercel preview deploy
+lk docs --server-url https://docs-abc123.vercel.app/mcp/ --vercel-header <token> overview
+```
+
 ## Additional notes
 
 ### Parameter precedence