#141 Part 1: Implement `parseItem` callback in `parseCollectionResponse` + unit tests

[Sam-Bolling]

Parent Issue

Split from #141 — parseCollectionResponse casts raw JSON to T[] without element validation.

This is Part 1 of 2. See also: Part 2 (integration test call-site updates — issue to follow).

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Scope — Part 1 Only

This part implements the core change (Option A from #141) and updates the unit test file. It does NOT touch integration test files — those are Part 2.

Files to Modify

File	Action	Est. Edits
src/ogc-api/csapi/formats/response.ts	Add parseItem callback parameter, replace as T[] casts	~10 lines
src/ogc-api/csapi/formats/response.spec.ts	Update existing call sites to pass parseItem; add malformed-element test	~15 lines

Implementation

Add a parseItem callback parameter to parseCollectionResponse (Option A from the parent issue):

export function parseCollectionResponse<T>(
  body: unknown,
  parseItem: (item: unknown, index: number) => T
): CollectionResponse<T> {
  // ...existing envelope normalization unchanged...
  const rawItems = Array.isArray(obj.features)
    ? obj.features
    : (obj.items as unknown[]);
  const items = rawItems.map((item, i) => parseItem(item, i));
  return { items, links, numberMatched, numberReturned, timeStamp };
}

What NOT to Touch

• ❌ Integration test files (discovery.spec.ts, command.spec.ts, navigation.spec.ts, observation.spec.ts, pipeline.spec.ts) — those are Part 2
• ❌ The CollectionResponse<T> interface definition
• ❌ Envelope normalization logic (links, numberMatched, timeStamp extraction)
• ❌ The links array cast at line 112
• ❌ Any file outside src/ogc-api/csapi/

Design Constraint

The parseItem callback is typed extraction, not validation reintroduction. The existing Part 2 parsers (parseDatastream, parseObservation, etc.) already take (json: unknown) => T and extract fields with type guards and defaults. The callback delegates to these existing tolerant parsers — it does NOT add a new validation layer. See Validation-Extraction Decoupling Design Notes.

Acceptance Criteria (Part 1)

• parseCollectionResponse requires a parseItem callback parameter
• No as T[] casts remain in the function
• response.spec.ts call sites updated to pass parseItem
• New test: server returning [null, 42, {"no-id": true}] — elements go through parseItem (no untyped cast)
• tsc --noEmit — zero errors
• response.spec.ts tests pass

Note: After Part 1, integration tests WILL fail because their call sites haven't been updated yet. That's expected — Part 2 fixes them.

Dependencies

Blocked by: Nothing
Blocks: Part 2 (integration test updates)

References

All references from #141 apply. Key ones for this part:

• docs/code-review/003-pending-p1-unchecked-generic-cast-response.md — original finding
• src/ogc-api/csapi/formats/response.ts lines 87–130 — affected function
• src/ogc-api/csapi/formats/part2.ts — existing per-item parsers that serve as parseItem callbacks
• Validation-Extraction Decoupling — design constraint

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Operational Constraints

⚠️ MANDATORY: Before starting work on this issue, review docs/governance/AI_OPERATIONAL_CONSTRAINTS.md.

Upstream Isolation Constraint

Per the upstream maintainer's comment on PR #136: all files in this part are within src/ogc-api/csapi/ — purely internal to the isolated CSAPI module.