ci: repair the MCP Inspector workflow (pin 2.0.0, drive via --config, make the steps able to fail)

[kalidke]

Inspector 2.0.0 shipped and turned main red with no change on our side, because the workflow invoked an unpinned npx @modelcontextprotocol/inspector. Fixing that exposed a second, worse problem: most of these steps could not fail.

Why it broke

2.0's CLI stops collecting the stdio target at the first dashed token (clients/cli/build/index.js, parseArgs), so julia --project=... server.jl lost its arguments. Bare julia then read stdin as Julia source and died on the first JSON-RPC frame:

ERROR: syntax: { } vector syntax is discontinued
{"error":{"code":"error","message":"Connection timed out after 15000 ms"}}

Upstream documents the constraint: "There is currently no way to pass a leading-dash argument through to a stdio server on the --cli command line; put it in the server entry's args in a catalog or config file instead." So the launch command now lives in .github/inspector/mcp-servers.json and is selected with --config/--server.

The steps could not fail

Independent of 2.0, four of seven Inspector steps asserted nothing or were fake-green:

• resources/list and resources/read only ran cat | jq . — an empty {"resources":[]} passed.
• prompts/get ended in || echo "Inspector may not support prompts/get".
• The mcp-remote HTTP step ended in || true, with a warn-only else branch.
• The direct-curl step had no jq -e at all, and an empty session id silently skipped the tools/list check.

Worse, jq -e on an empty file exits 0 (jq 1.6), and a failed Inspector call writes nothing to stdout — it reports the error on stderr and exits non-zero. So ... || true followed by jq -e passes on a total failure. assert-json.sh therefore checks emptiness before the filter, and filters now name expected values (current_time, the birthday URI and its July 31 contents, greeting/movie_analysis, echo) instead of length > 0, which passes against the wrong server.

Changes

.github/inspector/ (new)

• package.json + package-lock.json pin Inspector 2.0.0 and mcp-remote 0.1.38 with the full transitive graph (300 entries). An exact npx pkg@2.0.0 would still float 2.0.0's own ^ ranges.
• Under .github/ deliberately: a General-registry tarball ships the whole tree, and a root package.json makes a Julia package look like an npm project.
• dependabot.yml gains the npm ecosystem for that directory, so the pin is revisited rather than silently rotting — and a Dependabot PR runs this workflow, so the next breaking major arrives as a red PR instead of a red main.
• assert-json.sh, wait-http.sh (readiness polling replaces sleep 15; also detects a server that died during startup).

Workflow

• shell: bash workflow-wide so GitHub uses bash -eo pipefail. The implicit default is bash -e with no pipefail, under which a julia crash in sed | julia | tail -1 was masked by tail.
• actions/setup-node@v7 added — there was none, so the job used whatever Node the runner image shipped, and 2.0 requires ≥ 22.19.0.
• --format json for a stable stdout contract. It nests the payload under .result, hence the prefixed assertion paths.
• Primary HTTP coverage now uses the Inspector's native Streamable HTTP support, exercising our transport with no bridge in between. mcp-remote is kept as explicit Claude-Desktop-parity coverage (the docs tell users to configure it) — pinned, and it must pass now.
• prompts/get with arguments is covered through the Inspector; the comment claiming that was broken was stale (the flag is --prompt-args, plural). The raw JSON-RPC step stays as the one client-library-free path.
• Direct HTTP/JSON-RPC tests negotiate 2025-11-25 rather than 2025-06-18, so the smoke test exercises the version the package advertises.
• Dead http-sse push trigger removed.

Verification

Every run: block was extracted from the final YAML and executed locally against the real example servers, then confirmed in CI via workflow_dispatch (run 30509411640): both jobs green, 16 assertions each printing ok [...], Node v22.23.1, readiness in 3s.

Not included

The dry run surfaced an unrelated package bug — src/transports/http.jl:242 calls close(timer) and :546 calls flush(sse_stream), both resolving to the package's own Transport-only methods instead of Base, and both swallowed by catch. Filed separately; out of scope here.

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