fix(identity): /mcp defensive route backstop — worker-first, never the SPA shell (#196) - #237
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unforced merged 2 commits intoAug 11, 2026
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Adds /mcp to DEFENSIVE_PREFIXES alongside /vault: a Cloudflare zone route (my.parachute.computer/mcp*, already declared in workers/vault/wrangler.toml) is meant to intercept the canonical root MCP connector endpoint before it reaches this worker. If that route ever goes missing or is misconfigured, the identity worker now answers a loud 503 route_missing/mcp_route_missing instead of letting the SPA shell masquerade as a working MCP endpoint. - route-manifest.ts: /mcp added to DEFENSIVE_PREFIXES, third documented parity difference against the parachute-app SW denylist (the SW-side /^\/mcp(\/|$)/ entry is a separate follow-up in that repo). - index.ts: mcpRouteMissing handler mirrors vaultRouteMissing exactly (same response shape, same 503, live on every serving host from deploy). - wrangler.toml: "/mcp", "/mcp/*" added to run_worker_first in both the production and [env.staging] asset blocks. - Tests pinned: route-manifest.test.ts's drift-catcher + P0.3 parity suite, and a new "/mcp defensive backstop" describe block in static-assets-routing.test.ts (GET /mcp, GET /mcp/anything, POST /mcp). Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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…ash/query probes; verify-spa-routing checks the live backstop (cloud#196 review) Nits from review: static-assets-routing.test.ts's /mcp/anything case checked status + content-type but never error_type (the sibling /mcp case already does); add it, plus two cases for the spellings a hand-typed connector URL most plausibly takes (/mcp/, /mcp?foo=bar). verify-spa-routing.ts never probed any DEFENSIVE_PREFIXES path, so nothing proved run_worker_first actually claims /mcp at the live edge — add the /mcp probe, following the existing probe pattern.
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Cloud-side half of #196 (the parachute-app service-worker denylist entry is the separate follow-up the issue scopes out).
What
If the Cloudflare zone route dispatching
my.parachute.computer/mcp*to the vault worker ever vanishes, the identity worker now answers a loud503 mcp_route_missinginstead of silently serving the SPA shell to an MCP client:/mcp+/mcp/*added toDEFENSIVE_PREFIXES(route-manifest) with a dedicated 503 handlerrun_worker_firstentries in both prod and staging configs (parity pinned by the existing config tests)Tests (HEAD
d285268)identity 1096 pass / 0 fail (typecheck clean), vault 409 pass / 1 todo against the pinned core, control plane 177 pass. 503 coverage includes
/mcp,/mcp/anything,POST /mcp,/mcp/(trailing slash), and/mcp?foo=bar, all assertingerror_type: mcp_route_missing.scripts/verify-spa-routing.tsgains a live-edge/mcpprobe, closing the gap where a TOML typo would leave/mcpasset-first with every unit test still green.Caveat until the app half lands
On
my.with the PWA installed, a browser navigation to/mcpis still answered from the service worker's cached shell — MCP clients are unaffected. The manifest parity test records/mcpas manifest-only until the app-side denylist entry ships.🤖 Generated with Claude Code