id(world): records_read_pages_fit test red on main — panics no entry found for key at world/tests.rs:1169 #5128

Symptom

On current main, the pkgs/id lib test

world::tests::tests::records_read_pages_fit_the_result_event_that_delivers_them

fails with a panic:

thread panicked at src/world/tests.rs:1169:28:
no entry found for key

Evidence

• Reproduced on pristine origin/main 7657b97 (clean worktree, cargo test --lib with the test as filter): FAILED, same panic shape as the sibling failures.
• Also fails on the id(chain): integration tests do not compile — ChainExt initializers missing new link field #4522 fix branch (PR fix(id): name the checkpoint field in ChainExt test fixtures (#4522) #5117), whose diff touches only pkgs/id/tests integration fixtures — the lib target is unaffected by it, so this is independent of id(chain): integration tests do not compile — ChainExt initializers missing new link field #4522.
• Full lib run on the branch: 2023 passed / 3 failed / 6 ignored; the other two failures are already tracked: id(shell-contract): the directory client frame (PR #4954) is missing from the shell contract — contract test red on main #5020 (shell_contract directory frame) and id(world_fixture): tic-tac-toe determinism fixture recorded under a module hash the checked-in wasm no longer matches — replay test red on main #5021 (tic-tac-toe module hash drift, which also breaks cli_integration test_world_verify_rejects_agree_but_mismatch_header).

Why it matters

pkgs/id/flake.nix builds .#id-web with doCheck=true (checkType ci-check), so this failure — like #5020 and #5021 — fails the Nix check phase and blocks the laptop fleet switch even after the #4522 compile fix lands. #4522 makes the test targets compile again; this issue is one of the three runtime-red lib tests that then remain.

Suspects (unverified)

Recent records.read paging changes: 54ceece fix(id): bound records.read cap pages by the result-event limit (#4888) (#5092), and the id-core world_caps.rs change that arrived with merge de39ee8 (PR #4585). The panic is a map/index lookup miss inside the test at world/tests.rs:1169 — either the test fixture or the paging code disagrees about which key a page is stored under.

Acceptance

• The named test passes on main.
• cargo test --lib in pkgs/id shows this test green (the id(shell-contract): the directory client frame (PR #4954) is missing from the shell contract — contract test red on main #5020/id(world_fixture): tic-tac-toe determinism fixture recorded under a module hash the checked-in wasm no longer matches — replay test red on main #5021 failures are tracked separately).