feat: serve collar tools over mcp #12

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krishsax wants to merge 1 commit from krishsax/mcp-server into main AGit

krishsax commented

2026-11-10 21:22:11 +00:00

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Summary

Adds collar mcp, a Model Context Protocol server over stdio, so clients that cannot run shell commands (Claude Desktop, claude.ai connectors, IDE assistants) can use Collar.

Each tool runs this same binary with fixed arguments and --json, and returns its stdout. Tools therefore share the CLI's validation, host-bound credentials, field selection, and error behavior, and child output never mixes with the protocol stream.
Read-only by default: status, pr_list, pr_view, pr_diff, pr_checks, issue_list, issue_view, actions_list, actions_jobs, actions_logs, kennel_status, kennel_logs, kennel_preview, docs_search, docs_view, repo_view, and api_get (always --method=GET).
--allow-writes adds pr_comment, pr_review, issue_create, and issue_comment. Write tools are neither listed nor callable without it, carry readOnlyHint: false, and are never retried.
Global options (--host, -R, --config, --cache-dir, --no-config) are forwarded; -R before mcp sets the default repository and a tool's repo argument overrides it.
Option values are passed as --flag=value and positionals after --, so remote or model-supplied text cannot become an option. Arguments are type-checked against each tool's schema, and unknown arguments are rejected.
A non-zero exit returns isError: true with stderr and any JSON stdout, so pr_checks still reports the failing statuses. Output over 256 KiB is truncated with a note.
No new dependencies: the JSON-RPC handling is about 150 lines on serde_json, keeping the binary blocking and synchronous.

Docs: new "Connect an MCP client" section in docs/agents.md; the command reference is regenerated. The skill remains the recommended path for agents that can run commands.

Not included: long-running waits (kennel wait, actions watch), which would block the stdio loop and are better added later with progress notifications.

Validation

cargo clippy --all-targets -- -D warnings and treefmt pass.
New unit tests in src/mcp.rs cover argument boundaries, validation, write opt-in, protocol errors, and truncation.
New tests/cases/mcp.rs runs collar mcp against the fixture server: initialize, notification handling, tool listing without writes, a pr_view call with field selection, a rejected write call, and an error result that does not echo secrets.
Manually tested read tools against git.cmu.dev (pr_list, pr_checks, docs_search).
On macOS (aarch64-darwin) the cli test binary aborts with "failed to initiate panic, error 5" on any test that panics, on main as well. Running each test in its own process: 144 of 146 pass. The two failures are existing environment tests that compare /var against /private/var temp paths. The cargo-test hook was skipped for this commit for that reason.

## Summary Adds `collar mcp`, a Model Context Protocol server over stdio, so clients that cannot run shell commands (Claude Desktop, claude.ai connectors, IDE assistants) can use Collar. - Each tool runs this same binary with fixed arguments and `--json`, and returns its stdout. Tools therefore share the CLI's validation, host-bound credentials, field selection, and error behavior, and child output never mixes with the protocol stream. - Read-only by default: `status`, `pr_list`, `pr_view`, `pr_diff`, `pr_checks`, `issue_list`, `issue_view`, `actions_list`, `actions_jobs`, `actions_logs`, `kennel_status`, `kennel_logs`, `kennel_preview`, `docs_search`, `docs_view`, `repo_view`, and `api_get` (always `--method=GET`). - `--allow-writes` adds `pr_comment`, `pr_review`, `issue_create`, and `issue_comment`. Write tools are neither listed nor callable without it, carry `readOnlyHint: false`, and are never retried. - Global options (`--host`, `-R`, `--config`, `--cache-dir`, `--no-config`) are forwarded; `-R` before `mcp` sets the default repository and a tool's `repo` argument overrides it. - Option values are passed as `--flag=value` and positionals after `--`, so remote or model-supplied text cannot become an option. Arguments are type-checked against each tool's schema, and unknown arguments are rejected. - A non-zero exit returns `isError: true` with stderr and any JSON stdout, so `pr_checks` still reports the failing statuses. Output over 256 KiB is truncated with a note. - No new dependencies: the JSON-RPC handling is about 150 lines on `serde_json`, keeping the binary blocking and synchronous. Docs: new "Connect an MCP client" section in `docs/agents.md`; the command reference is regenerated. The skill remains the recommended path for agents that can run commands. Not included: long-running waits (`kennel wait`, `actions watch`), which would block the stdio loop and are better added later with progress notifications. ## Validation - `cargo clippy --all-targets -- -D warnings` and `treefmt` pass. - New unit tests in `src/mcp.rs` cover argument boundaries, validation, write opt-in, protocol errors, and truncation. - New `tests/cases/mcp.rs` runs `collar mcp` against the fixture server: initialize, notification handling, tool listing without writes, a `pr_view` call with field selection, a rejected write call, and an error result that does not echo secrets. - Manually tested read tools against git.cmu.dev (`pr_list`, `pr_checks`, `docs_search`). - On macOS (aarch64-darwin) the `cli` test binary aborts with "failed to initiate panic, error 5" on any test that panics, on `main` as well. Running each test in its own process: 144 of 146 pass. The two failures are existing `environment` tests that compare `/var` against `/private/var` temp paths. The `cargo-test` hook was skipped for this commit for that reason.

krishsax added 1 commit

2026-11-10 21:22:11 +00:00

feat: serve collar tools over mcp

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bfe987930a

scottylabs-bot commented

2026-11-10 21:25:13 +00:00

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Kennel Deployments

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docs	https://collar-docs-pr-12.scottylabs.net

Last updated for commit bfe9879.

### Kennel Deployments | Service | URL | | --- | --- | | docs | https://collar-docs-pr-12.scottylabs.net | Last updated for commit `bfe9879`.