fix: encode the mcp subcommand in server.json package arguments

[thymikee]

Problem

Registry-format launchers start the server from the package descriptor only. server.json declared the npm package with a stdio transport but no packageArguments, so a client honoring the MCP registry entry (or the website's new /.well-known/mcp.json discovery manifest) runs the bare agent-device CLI instead of the stdio MCP server — src/bin.ts only starts the MCP server for the mcp subcommand.

Change

• scripts/sync-mcp-metadata.mjs now writes the fixed positional mcp argument into the package entry, so the sync script, CI (check:mcp-metadata), and prepack all keep the invariant instead of relying on the file being hand-edited.
• Regenerated server.json accordingly.

Verification

pnpm sync:mcp-metadata
pnpm check:mcp-metadata   # passes

Resulting entry:

"packages": [{
  "registryType": "npm",
  "identifier": "agent-device",
  "version": "0.20.11-dev",
  "transport": { "type": "stdio" },
  "packageArguments": [{ "type": "positional", "value": "mcp" }]
}]

Companion: website PR callstack-internal/v0-agent-device#10 ships the same shape at https://agent-device.dev/.well-known/mcp.json so the two sources of truth do not diverge.

[github-actions]

Size Report

Metric	Base	Current	Diff
JS raw	2.60 MB	2.60 MB	-2.9 kB
JS gzip	875.8 kB	874.3 kB	-1.5 kB
npm bundled raw	2.60 MB	2.60 MB	-2.9 kB
npm bundled gzip	875.8 kB	874.3 kB	-1.5 kB
npm tarball	1.03 MB	1.03 MB	-1.4 kB
npm unpacked	3.48 MB	3.48 MB	-3.2 kB
npm clean-installed	3.48 MB	3.48 MB	-3.2 kB

npm unpacked components

Component	Base	Current	Diff
JS / dist source	2.76 MB	2.76 MB	-3.3 kB
Apple runner source/project	544.4 kB	544.4 kB	0 B
Apple snapshot presentation source	33.8 kB	33.8 kB	0 B
macOS helper source	54.8 kB	54.8 kB	0 B
Android helper artifacts	43.3 kB	43.3 kB	0 B
Other package files	46.4 kB	46.5 kB	+114 B

Startup median (7 runs, lower is better):

Scenario	Base	Current	Diff
CLI --version	25.4 ms	25.1 ms	-0.3 ms
CLI --help	63.3 ms	63.3 ms	+0.0 ms

Top changed chunks:

Chunk	Raw diff	Gzip diff
dist/src/session2.js	-573 B	-161 B
dist/src/daemon-client-lifecycle.js	+552 B	+129 B
dist/src/internal/daemon.js	-66 B	-16 B

Top changed packed files

Packed file	Base	Current	Diff
dist/src/artifact-download.js	2.6 kB	0 B	-2.6 kB
dist/src/http-health.js	655 B	1.9 kB	+1.3 kB
dist/src/transport.js	1.3 kB	0 B	-1.3 kB
dist/src/session2.js	218.6 kB	218.0 kB	-573 B
dist/src/daemon-client-lifecycle.js	41.9 kB	42.4 kB	+552 B
dist/src/client-types.d.ts	57.9 kB	57.5 kB	-412 B
dist/src/byte-limit-stream.js	398 B	0 B	-398 B
dist/src/archive.js	7.9 kB	8.2 kB	+272 B
server.json	602 B	716 B	+114 B
dist/src/internal/daemon.js	107.8 kB	107.8 kB	-66 B

[thymikee]

BLOCKED at exact head 87fadfd. The packageArguments shape is correct and matches the MCP Registry schema, but the regression proof is incomplete: add an owning metadata test/gate assertion that finds the agent-device npm package entry and requires the exact fixed positional argument [{ type: "positional", value: "mcp" }], with planted-red evidence for a missing/wrong argument. The current check only demonstrates the corrected file is self-consistent. Also add a concise Unreleased changelog entry: registry-format clients currently launch the bare CLI, so this is a user-visible release fix. No device proof is required; exact-head CI and size are otherwise clean.

[thymikee]

Both asks addressed in 21083ca:

1. Owning metadata test with planted-red evidence — new scripts/__tests__/mcp-metadata.test.ts (wired into the unit-core project include list, so the unit lane owns it). It finds the agent-device npm package entry in the checked-in server.json by package.json name and asserts the exact fixed positional argument, in both failure directions:

Red #1 — argument missing (server.json reverted to the pre-fix shape):

FAIL  |unit-core| scripts/__tests__/mcp-metadata.test.ts > the published registry entry starts the MCP server, not the bare CLI
AssertionError: registry-format launchers must start the stdio MCP server; without the fixed mcp subcommand they run the bare CLI
+ actual - expected
+ undefined
- [
-   {
-     type: 'positional',
-     value: 'mcp'
-   }
- ]

Red #2 — wrong argument (value: 'cli'):

AssertionError: registry-format launchers must start the stdio MCP server; without the fixed mcp subcommand they run the bare CLI
  [
    {
      type: 'positional',
+     value: 'cli'
-     value: 'mcp'
    }
  ]

Green — with the shipped file: vitest run --project unit-core scripts/__tests__/mcp-metadata.test.ts → 1 passed; pnpm check:mcp-metadata and oxfmt/oxlint clean.

2. Changelog — Unreleased entry added:

Fixed: the MCP registry entry (server.json) now declares the fixed mcp subcommand via packageArguments, so a registry-format launcher — the MCP Registry or the website's /.well-known/mcp.json discovery manifest — starts the stdio MCP server. Previously it ran agent-device with no subcommand, i.e. the bare CLI (#2275).

[thymikee]

Re-review of 21083ca3416de24e89607f19b12d0ccd825258a6: the prior code/documentation asks are resolved. scripts/__tests__/mcp-metadata.test.ts finds the agent-device npm entry by package name and pins npm + stdio + the exact fixed [{ type: "positional", value: "mcp" }] argument; it is owned by unit-core, and the response records planted-red output for both missing and wrong arguments. The Unreleased changelog now documents the user-visible bare-CLI launch bug. No remaining code finding; no device proof is needed.

Still not merge-ready on exact-head evidence: Repo Guards failed in the unchanged scripts/node-test-tmpdir.test.ts orphan-consumer timing case (expected the abandoned run dir to be pruned, observed []). This PR changes no TMPDIR code, so it appears to be an infrastructure/timing flake. Rerun that guard and await the remaining in-progress checks; if they finish green, this head is READY.

[thymikee]

Both exact-head failures are infrastructure flakes in code this PR does not touch; reran the failed jobs (runs 33850336605 / 33850336650):

• Repo Guards — scripts/node-test-tmpdir.test.ts:305 (a run whose owner alone was killed keeps its directory while a child still uses it, and loses it once the child exits): the orphan-pruning assertion saw [] where it expected the abandoned run dir. TMPDIR code is untouched by this PR (diff is server.json, the sync script, the new metadata test, the vitest include entry, and the changelog).
• Smoke Tests (iOS runner lane) — all 5 failures are the same case, RunnerTests.testBareTypeUsesTappedInputWhenSoftwareKeyboardIsHidden, a software-keyboard timing case in the Swift runner (the keyboard-existence check retried ~8s before failing); the other three smoke lanes on this head pass. No Swift or runner code is touched by this PR.

Awaiting the reruns to finish; this head should then be READY per the re-review.

[thymikee]

Reruns finished green: Repo Guards pass (3m44s) and the rerun Smoke Tests iOS runner lane pass (15m39s). Full check suite is green on exact head 21083ca — per the re-review, this head is READY.

[github-actions]

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2026-09-04 08:53 UTC