Add Amp plugin for Unity MCP#1118
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Adds .amp/plugins/unity-mcp.ts — a thin Amp plugin that exposes a single
`unity` tool. The tool POSTs to the existing Python MCP server's
/api/command REST endpoint, so the Python side keeps the full tool catalog
and Amp only sees one tool definition (low token cost).
- Single tool: { tool, params, unity_instance? }
- Palette command: 'Unity: Status' (hits /api/instances)
- Configurable via UNITY_MCP_SERVER_URL and UNITY_MCP_TIMEOUT_MS
- session.start logs whether a Unity instance is connected
Amp-Thread-ID: https://ampcode.com/threads/T-019e144f-2307-731e-b3d4-d3bcd4b298b3
Co-authored-by: Amp <amp@ampcode.com>
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📝 WalkthroughWalkthroughAdds a new Amp plugin that proxies Unity MCP REST calls, with helpers for URL/timeouts/command building, unit tests exercising network/error/timeout behaviors, and a GitHub Actions workflow to run the tests. ChangesUnity MCP Plugin
CI: Amp Plugin Tests workflow
Estimated code review effort🎯 3 (Moderate) | ⏱️ ~25 minutes Poem
🚥 Pre-merge checks | ✅ 5✅ Passed checks (5 passed)
✏️ Tip: You can configure your own custom pre-merge checks in the settings. ✨ Finishing Touches🧪 Generate unit tests (beta)
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Actionable comments posted: 1
🤖 Prompt for all review comments with AI agents
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.
Inline comments:
In @.amp/plugins/unity-mcp.ts:
- Around line 20-30: The TIMEOUT_MS constant can become NaN or non-positive from
process.env and cause immediate aborts in postCommand; replace the simple
Number(...) assignment with robust parsing that ensures a finite positive
integer (e.g., parseInt/Number, check Number.isFinite and >0) and clamp to a
sane default (120000 ms) using Math.max or a conditional fallback before it's
used to create the timer in postCommand; update the TIMEOUT_MS definition (and
any uses in postCommand where ctrl/timer are created) so the timeout is always a
positive finite millisecond value.
🪄 Autofix (Beta)
Fix all unresolved CodeRabbit comments on this PR:
- Push a commit to this branch (recommended)
- Create a new PR with the fixes
- Harden UNITY_MCP_TIMEOUT_MS parsing: clamp NaN/non-numeric/non-positive/ non-finite values to the 120s default. Without this, Number(undefined) yields NaN and AbortController fires immediately, aborting every request before the network is touched. - Add JSDoc/TSDoc on every exported symbol and the plugin entry point to satisfy the 80% docstring coverage check. - Refactor: extract pure helpers (resolveTimeoutMs, normalizeBaseUrl, buildCommandBody, formatUnreachableError, postCommand, listInstances) with an injectable FetchLike type so they can be unit-tested without a live network. - Add 28 unit tests in .amp/plugins/__tests__/unity-mcp.test.ts covering timeout parsing edge cases, URL normalization, body construction, unreachable-error formatting, and postCommand/listInstances behavior (success, non-2xx with body, non-2xx without body, network failure, timeout abort). - Add .github/workflows/amp-plugin-tests.yml to run 'bun test' on every push/PR that touches .amp/plugins/**. Amp-Thread-ID: https://ampcode.com/threads/T-019e144f-2307-731e-b3d4-d3bcd4b298b3 Co-authored-by: Amp <amp@ampcode.com>
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Type of Change
New feature: Added .amp/plugins/unity-mcp.ts to enable Amp-to-Unity integration.
Changes Made
Plugin Architecture: Implemented a thin TypeScript plugin that acts as a REST proxy to the existing Python MCP server.
Tool Consolidation: Registered a single unity tool in Amp. This tool uses a tool parameter to dispatch commands to the Python server’s 38+ underlying Unity tools, significantly reducing context window token overhead.
Command Registry: Added a Unity: Status command to the palette for instance discovery via the /api/instances endpoint.
Lifecycle Management: Integrated a session.start listener to log server reachability and active Unity instance counts upon plugin initialization.
Configuration Support: Exposed UNITY_MCP_SERVER_URL and UNITY_MCP_TIMEOUT_MS for environment-based overrides.
Testing: Added unit tests for the REST proxy logic to satisfy CI/CodeRabbit requirements (overriding the initial "out of scope" plan).
Testing/Screenshots
Activation: Verified via amp plugins list; the unity tool and session.start listener are correctly reported as active.
Execution: Successfully ran amp plugins exec .amp/plugins/unity-mcp.ts session.start --data '{}', confirming reachability of the live Python server and instance reporting.
Model Interaction: Confirmed the model successfully references the unity-mcp-orchestrator skill for downstream schema details without requiring local schema duplication.
Documentation Updates
[x] Updated in-code documentation for the unity tool parameters.
[x] Documented environment variables (UNITY_MCP_SERVER_URL, UNITY_MCP_TIMEOUT_MS) in the plugin header.
[n/a] External docs (README) updates—deferred until the Python server orchestration is finalized.
Related Issues
Relates to: Existing unity-mcp Python server implementation.
Summary by CodeRabbit
New Features
Tests
Chores