feat: add code search tools (search_code, search_project_code, search_group_code)

[pacifical]

Closes #280

Adds three code search tools using the GitLab Search API blobs scope:

• search_code — global code search across all projects (GET /search?scope=blobs)
• search_project_code — search within a specific project (GET /projects/:id/search?scope=blobs)
• search_group_code — search within a specific group (GET /groups/:id/search?scope=blobs)

All three tools support optional filters: ref, filename, path, extension, and pagination (page, per_page).

Toolset

New search toolset with isDefault: false (opt-in). Requires advanced search or exact code search enabled
on the GitLab instance.

Enable via:

GITLAB_TOOLSETS="search" npx @zereight/mcp-gitlab
# or individually
GITLAB_TOOLS="search_code,search_project_code" npx @zereight/mcp-gitlab

Changes

┌──────────────────────────────────┬─────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
│               File               │                                                   Change                                                    │
├──────────────────────────────────┼─────────────────────────────────────────────────────────────────────────────────────────────────────────────┤
│ schemas.ts                       │ Zod schemas: GitLabSearchBlobResultSchema, SearchCodeSchema, SearchProjectCodeSchema, SearchGroupCodeSchema │
├──────────────────────────────────┼─────────────────────────────────────────────────────────────────────────────────────────────────────────────┤
│ index.ts                         │ searchBlobs() shared API function, 3 handleToolCall cases, toolset registration, readOnlyTools entries      │
├──────────────────────────────────┼─────────────────────────────────────────────────────────────────────────────────────────────────────────────┤
│ test/test-search-code.ts         │ 5 mock tests (toolset filtering, tool invocation for all 3 scopes, opt-in verification)                     │
├──────────────────────────────────┼─────────────────────────────────────────────────────────────────────────────────────────────────────────────┤
│ test/utils/mock-gitlab-server.ts │ Mock endpoints for /search, /projects/:id/search, /groups/:id/search                                        │
├──────────────────────────────────┼─────────────────────────────────────────────────────────────────────────────────────────────────────────────┤
│ test/test-toolset-filtering.ts   │ Updated tool counts and sample tools for search toolset                                                     │
├──────────────────────────────────┼─────────────────────────────────────────────────────────────────────────────────────────────────────────────┤
│ package.json                     │ Added search + toolset-filtering tests to test:mock                                                         │
├──────────────────────────────────┼─────────────────────────────────────────────────────────────────────────────────────────────────────────────┤
│ README.md                        │ Documented search toolset and 3 new tools                                                                   │
└──────────────────────────────────┴─────────────────────────────────────────────────────────────────────────────────────────────────────────────┘

[pacifical]

@zereight do you mind taking a look?

[DarkByteZero]

Nice implementation! I was actually looking into implementing a similar feature myself and noticed this PR already exists, so I wanted to share a couple of thoughts that might help extend it a bit further.

1. REST vs GraphQL code search APIs

GitLab currently exposes code search through two different APIs:

• REST API
  GET /search?scope=blobs
  Returns flat results such as data, path, and startline.

• GraphQL API
  blobSearch
  Returns richer structured results such as files grouped with multiple match chunks, line numbers, language detection, and match counts.

One small detail though: GraphQL blobSearch seems to be tied to exact code search / Zoekt, so it is probably not a drop-in replacement for every GitLab code search setup.

Because of that, it might be worth making this configurable, for example via something like GITLAB_CODE_SEARCH_API=rest|graphql, or handling it conditionally:

• use REST /search?scope=blobs as the general path
• optionally use GraphQL blobSearch when targeting Zoekt / exact code search

2. Zoekt query syntax could be documented in the tool description

If the instance has exact code search (Zoekt) enabled, the search query supports a much richer inline syntax:

Docs: Exact code search syntax

Examples:

Query	Meaning
"class foo"	Exact match
foo file:^doc/	Search in directories starting with /doc
foo -bar	foo but not bar
foo lang:ruby	foo in Ruby source code
foo file:\.js$	foo in .js files
sym:foo	Search in symbols (class/method/variable names)
class Foo case:yes	Case-sensitive search

Since these filters (file:, lang:, etc.) are embedded directly in the query string, they may overlap with separate parameters like filename, path, or extension, which are more REST / advanced-search style filters.

Not a blocker of course, just something I ran into while exploring the same area and thought might be useful context.

[pacifical]

@DarkByteZero thanks for your feedback. agreed on the tool description, added this.
I did actually try to explore the graphql way, but gave up eventually, since generic graphql is already available as a standalone tool here, and more importantly - I got bored :)

[DarkByteZero]

i mean when this gets merged i can build onto that, thanks