feat(code-mode): use server names for MCP extensions

[codefromthecrypt]

Summary

Makes code mode usable in ACP and improves extension naming for better LLM accuracy.

Code mode in ACP: Adds --with-builtin arg so ACP clients can enable code_execution and developer extensions.

Better extension names: When no name is configured (e.g., CLI --with-streamable-http-extension), extensions now use server-declared names instead of anonymous identifiers. User-configured names from goose config or ACP sessions are still preferred.

Before (CLI arg, no configured name):

$ goose run --with-streamable-http-extension 'https://mcp.kiwi.com'   -t 'Use kiwi to find the fastest itinerary from BKI to SYD tomorrow'
--snip--
─── search-flight | mcpkiwicom_yfvx6ext ──────────────────────────

After:

─── search-flight | kiwi-mcp-server ──────────────────────────

LLMs can now match extension names to server info in their prompts. Collision suffix added when duplicate names exist.

Type of Change

• Feature
• Tests

AI Assistance

• This PR was created or reviewed with AI assistance

Testing

New integration test: test_acp_with_builtin_and_mcp - verifies code_execution and MCP servers work together in ACP mode.

Manual:

goose run --with-streamable-http-extension 'https://mcp.kiwi.com'   -t 'Use kiwi to find the fastest itinerary from BKI to SYD tomorrow'

Related Issues

Closes #6188

[Copilot]

Pull request overview

This PR enhances MCP extension handling in goose by enabling code mode in ACP and improving extension naming for better LLM interaction.

Key Changes

• ACP code mode support: Adds --with-builtin CLI argument allowing ACP clients to enable built-in extensions like code_execution and developer
• Server-based extension naming: Extensions without configured names now use MCP server-declared names instead of random identifiers, with collision detection
• Search filtering: Excludes extensionmanager from code_execution search results to reduce LLM confusion about internal tools

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
crates/goose/src/agents/extension_manager.rs	Adds resolve_extension_name() function to use server-declared names with collision handling via random suffixes
crates/goose/src/agents/code_execution_extension.rs	Filters out extensionmanager from module search results
crates/goose-cli/src/session/mod.rs	Removes generate_extension_name() - extensions now use empty name strings to trigger server name resolution
crates/goose-cli/src/commands/acp.rs	Adds add_builtins() helper and --with-builtin parameter support for ACP mode
crates/goose-cli/src/cli.rs	Adds --with-builtin CLI argument with comma-separated builtin names
crates/goose/tests/acp_integration_test.rs	Adds test_acp_with_builtin_and_mcp integration test verifying code_execution works with MCP servers, updates test server to declare explicit name
crates/goose/tests/test_data/openai_*.txt	Updates test fixtures with new model format and adds builtin extension interaction test data

[codefromthecrypt]

FYI: all of these are real server names scraped from the public MCP impls

[Copilot]

Pull request overview

Copilot reviewed 11 out of 11 changed files in this pull request and generated no new comments.

[Copilot]

Pull request overview

Copilot reviewed 11 out of 11 changed files in this pull request and generated no new comments.

[Copilot]

Pull request overview

Copilot reviewed 14 out of 15 changed files in this pull request and generated no new comments.

[codefromthecrypt]

added this to isolate the DBs between tests, but allow us to intentionally share them. This will be very important in subsequent change for session load, resume and list capabilities

[michaelneale]

makes sense.

[Copilot]

Pull request overview

Copilot reviewed 13 out of 14 changed files in this pull request and generated 2 comments.

[michaelneale]

I'm not sure why - but the GUI isn't working with this - never get a response, no matter what I do (I just flicked to main and tried again) - if I turn off code mode it is fine.