Add API Resource

Add an API resource (to an existing service)

Every request the app makes goes through a resource: an entry in the per-service registry under src/api/resources/services/** that maps a service:name key (e.g. core:token, stats:lines) to a path template and, via a sibling conditional type, to its response type. This skill declares new resource(s) in an existing service.

Out of scope — brand-new service. That also touches src/api/resources/index.ts (registration + dispatch-type branches) and a src/api/config.ts block; not covered here.

Out of scope — consuming the resource. Wiring it into UI (useApiQuery / useQueryWithPages, stubs) is the caller's job; this skill only makes the resource exist and be correctly typed.

Background reading: Where a resource's response types come from in src/api/CONTEXT.md — read it before Step 3.

Rule of thumb: never guess. Whenever information is missing or required to proceed, pause and ask the user, or confirm your findings, before writing files.

Step 0 — Interview (REQUIRED before writing anything)

Collect for each resource, and confirm with the user:

1. Service + endpoint path — must come from the user or the task description. Never hunt for endpoints in specs or type packages yourself; if the path (or the HTTP service it belongs to) isn't given, ask. Then propose the service:name key — follow the naming of the sibling entries in the service's registry file.
2. A live instance that has the endpoint deployed — an alias from tools/dev-server/registry.json or a full instance URL. A brand-new endpoint may exist only on a staging instance; ask which. This powers Step 1.
3. Types-package state — ask whether the response interface is already available in a published version of the service's types package. For a brand-new endpoint it often isn't (stable versions are published only on API releases). If yes, the user should provide the exact version of the package. If not — or the user is unsure — collect the publish-beta-types Step 0 inputs now (most importantly the API source-repo branch to publish from), so the publish can run later without another interview. If the user already knows publishing is impossible, settle the fallback choice now too — see Worst case in Step 3.
4. Filters / sorting — note only the filters/sorts the task description explicitly names (see Step 4). Do not derive any from the API.

Step 1 — Fetch a real sample response

Resolve each resource's real URL with the resolve-api-url skill, then make one GET per resource and save each body to the scratchpad. This sample is load-bearing three times over:

• it proves the endpoint exists on the chosen instance (a 404 here stops the task);
• it settles pagination deterministically — the resource is paginated iff the body has a next_page_params field (Step 2);
• it is the ground truth for typing (Step 3) and later for stub values in the wiring phase.

If the endpoint needs auth or params you can't supply, show the user the resolved URL and ask them for a sample body instead.

Step 2 — Add the resource entry

All edits for an existing service live in its registry file — Core API: src/api/resources/services/core/<group>.ts (e.g. token.ts); micro-service: src/api/resources/services/<name>.ts. Add the entry to the *_API_RESOURCES object — shape is ApiResource (src/api/resources/types.ts): { path, pathParams?, filterFields?, paginated?, headers? }.

• path uses :param placeholders; list each one in pathParams.
• paginated: true only if the Step 1 sample has next_page_params.

No src/api/resources/index.ts edit is needed — the ResourceName union and the dispatch types aggregate per-service keys automatically.

Step 3 — Add the payload-type branch

Add a matching branch to the sibling *ResourcePayload<R> conditional type in the same file. Miss this and ResourcePayload<'service:new'> silently resolves to never — no error at the declaration, just untyped data downstream. Where the response type comes from depends on the API:

• Core API — use the generated @blockscout/api-types package; its README Usage section (node_modules/@blockscout/api-types/README.md) is the reference for how to name a response type (schemas[…], operations[…], paths[…]['get']).
• Micro-service APIs — the types package has no path → response-type map, so the connection can't be derived mechanically. Pick the interface that looks right for the endpoint, check it field-by-field against the Step 1 sample body, and confirm the choice with the user before relying on it.
• Local types — some payloads are hand-typed in a slice/feature types/api.ts rather than generated; see Where a resource's response types come from in src/api/CONTEXT.md.

Type not published yet? If Step 0 established the interface isn't in any published package version, don't hand-type a stopgap: invoke the publish-beta-types skill with the inputs already collected in Step 0, then continue with this step. Same move if you only discover the gap here (the interface missing from node_modules even at latest despite the interview answer) — in that case the publish inputs still need collecting.

Worst case — no published types and no publish possible (no access to the API repo, publish workflow broken, or the API branch doesn't generate types for the endpoint yet, so there's nothing to publish). Confirm the blocker, then the user picks one of two paths — never pick silently:

• Temporary local type — hand-type the payload in the owning slice/feature types/api.ts (the usual home for local types — see Where a resource's response types come from in src/api/CONTEXT.md; some core:* payloads already live this way), derived from the Step 1 sample body, and reference it from the payload branch. Mark it // TODO (api-types): replace with the generated @blockscout/<pkg> type once published so the swap can be found with a grep later. Caveat: one sample can't reveal optional/nullable fields — confirm optionality with the user instead of inferring it from a single body.
• Defer the resource — stop here, leaving the resource undeclared until types can be published. In a page flow this degrades to layout-only (the page's TODO (api-data): markers stay in place).

Step 4 — Filters / sorting (only when the task names them)

Not every paginated resource has them. Add filterFields and branches to the service's *PaginationFilters<R> / *PaginationSorting<R> types only for the filters/sorts named in the task description or conversation — never infer them from the API. Define the filter/sort types themselves in the owning slice/feature types/api.ts (kept local by design).

Step 5 — Verify

Run pnpm run lint:tsc. To catch a missed Step 3 branch (the silent never), use the inline type-assertion pattern already present in src/api/resources/index.ts (e.g. the ResourcePayload<'core:api_keys'> / ResourcePathParams<'bens:address_domain'> checks) as a temporary probe for your new key — or hover/tsc-check a ResourcePayload<'service:new'> usage and confirm it is not never.

Output

Report back, per resource: the service:name key, the payload type (and its origin — package or local), whether it's paginated, and the scratchpad path of the sample body — everything a follow-up consumption task needs.