PR #3546 · The gate that could not see its own staleness

.mcp.json is gitignored and absent in CI, so the MCP gate hand-copied a snapshot of it into a shell literal. A hand-copied snapshot of mutable config cannot detect its own staleness. On 2026-08-18 the context7 entry moved from npx stdio to hosted HTTP and the literal went on asserting the old shape, silently. Pick a failure condition on the left and watch both gates answer it: the old literal passes while wrong on four of the six.

1 · Failure condition

One state of the tree. Each row is a measured run.

2 · Environment

Is the untracked .mcp.json on disk?

3 · Gate version

Before and after the change in this PR.

The old gate pinned CONFIGURED_SERVERS as a dated shell string. The new gate reads tests/agents/mcp-servers.manifest.json, which is tracked and reviewed.

Repo surface before this work

Why a silent grant check matters here

agent files

mention mcp__context7__

grant it in frontmatter

advertise it in prose, scoped to mcpServers: [tavily]

old hardcoded literal

new tracked manifest

Six states, both gates, measured

Rows shaded amber are the ones where the old gate reports success on a broken tree. Old-gate results assume .mcp.json is present, which is the friendliest case for it: it never opens the file at all.

State of the tree	Old	New	What the new gate says

Three behaviors the literal could not provide. (1) When .mcp.json is present the gate diffs it against the manifest and fails on drift, covering membership and transport. (2) When it is absent the gate runs fully off the manifest, so CI and local behave identically. (3) It prints which source it used, so a reader cannot mistake a fallback for a real read, and it exits non-zero on a missing or malformed manifest instead of passing vacuously on an empty list.

Six states, both gates, measured

Why the manifest records provenance, not just names