[mydd7]

Reddit Enhancement Suite's content script stops at requestIdleCallback when WebKit does not provide that global (#344). The extension compatibility layer now provides request/cancel idle callbacks in extension pages and content-script contexts when the request API is missing.

The fallback yields through a timer and supplies a decreasing budget capped at 50 ms. If the requested positive timeout has elapsed before delivery, it reports didTimeout: true with no remaining budget. Cancellation removes the timer. Native implementations are retained; workers and ordinary page-world scripts do not gain this Window API.

This is a timer-based compatibility fallback, not WebKit idle detection. Deadline and timeout behavior follow the requestIdleCallback specification. The separate diagnostics suggestion in #344 is outside this change.

Validation on Windows:

• Before the fix: 4 new cases failed because requestIdleCallback was absent; 18 passed.
• node --test crates/zephium-webext-macos/tests/compat.test.mjs: all 22 passed.
• Tests cover deferred execution, cancellation, decreasing/nonnegative budgets, elapsed and unexpired timeouts, native preservation, worker scope and page-world isolation.
• cargo test -p zephium-webext-macos --locked: the Node integration harness passed. This is not a macOS native build.
• cargo clippy -p zephium-webext-macos --all-targets --locked -- -D warnings
• cargo fmt --all --check, JavaScript syntax checks and git diff --check passed.

RES startup in a packaged macOS build still needs verification. No Rust, IPC or frame code changed.

Summary by CodeRabbit

• New Features
  • Added support for scheduling and cancelling idle callbacks in supported page and content contexts where native idle-callback APIs are unavailable.
  • Callbacks run asynchronously and receive a time budget; optional timeouts determine whether a callback is reported as timed out.
  • Existing native behavior is preserved, and these APIs remain unavailable in worker contexts and ordinary pages without extension context.

[coderabbitai]

No actionable comments were generated in the recent review.

Recent review info

Run configuration

• Source mode: Auto
• Repository: zephium-browser/Zephium
• Branch: main
• File: .coderabbit.yaml
• Commit: f0dba76
• Layers: Repository YAML
• Review profile: CHILL
• Plan: Advanced
• Run ID: fae4600b-b14a-47b8-bd0e-e3fe09be2aa1

Commits

Reviewing files that changed from the base of the PR and between f0dba76 and e89c662.

Files selected for processing: 2

• crates/zephium-webext-macos/src/compat/compat.js
• crates/zephium-webext-macos/tests/compat.test.mjs

Included review availability: This review used your included allowance. Your plan provides up to 4 included reviews per hour; 3 remain after this review.

Walkthrough

The macOS compatibility layer adds timer-backed requestIdleCallback and cancelIdleCallback APIs in supported extension contexts. Tests cover asynchronous callbacks, deadlines, timeouts, cancellation, native API retention, and context-specific availability.

Changes: Idle callback fallback

Layer / File(s)	Summary
Fallback behavior and context validation crates/zephium-webext-macos/src/compat/compat.js, crates/zephium-webext-macos/tests/compat.test.mjs	The compatibility layer adds a timer-backed idle callback implementation with callback validation, timeout handling, a deadline, and cancellation. Tests cover page and content contexts, native API retention, and contexts where the APIs remain unavailable.

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix

Possibly related issues

• Issue 344 reports a missing requestIdleCallback in WebKit RES content scripts. This change adds a fallback for content-script contexts.

Suggested labels: bug, area: extensions, platform: macos, size: S

Merge Risk: Low · up to e89c6

Passing an unrelated timer handle to idle cancellation can stop that timer. Normal use is unaffected, so the risk is bounded.

Pre-merge checks: 9 · 1

Failed checks: 1 warning

Check name	Status	Explanation	Resolution
Performance Impact Stated		The change touches startup code. compat.js runs first in every extension context, and the new block adds initialization in non-worker pages and content scripts. The description explains timer and de…	Add a Performance Impact section to the PR description. State the added startup work, the per-call timer overhead when the fallback is used, and whether the change affects content-script or extension-page startup. Include measured startup o…

Passed checks: 9 passed

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title uses the required Conventional Commits format with the valid type fix, scope webext, and an imperative summary that accurately describes the idle callback fallback change.
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.
One Logical Change		The pull request changes only compat.js and its compatibility test file. The implementation adds the described idle-callback fallback, and the test changes support and verify that behavior. The diff…
Linked Issue For Larger Changes		The PR is a small, contained bug fix. The diff changes only the compatibility layer and its tests, and adds fallback idle callbacks for the reported WebKit gap. It does not add a broad feature, alter …
Tests Cover Changed Behavior		The PR adds tests for the changed idle-callback behavior. The tests cover asynchronous delivery, the 50 ms decreasing and nonnegative deadline, expired and unexpired timeouts, cancellation, invalid ca…
Generated Files Follow Their Source		The pull request changes only crates/zephium-webext-macos/src/compat/compat.js and its test file. It does not change frame/src/shared/ipc/bindings.ts, Cargo.lock, pnpm-lock.yaml, or generated …
Privileged Boundary Intact		The authoritative diff contains only compat.js and compat.test.mjs. The production change adds local timer-based requestIdleCallback and cancelIdleCallback functions. It does not add Tauri IPC…

Full details: One Logical Change

Explanation

The pull request changes only compat.js and its compatibility test file. The implementation adds the described idle-callback fallback, and the test changes support and verify that behavior. The diff contains no unrelated refactoring, renaming, or reformatting.

Full details: Linked Issue For Larger Changes

Explanation

The PR is a small, contained bug fix. The diff changes only the compatibility layer and its tests, and adds fallback idle callbacks for the reported WebKit gap. It does not add a broad feature, alter user-facing UI, or refactor across modules. The check therefore passes even though the description uses a plain issue reference rather than a Closes/Fixes/Refs keyword.

Full details: Tests Cover Changed Behavior

Explanation

The PR adds tests for the changed idle-callback behavior. The tests cover asynchronous delivery, the 50 ms decreasing and nonnegative deadline, expired and unexpired timeouts, cancellation, invalid callbacks (TypeError), native API preservation, worker exclusion, and ordinary page-world exclusion. The changed file is JavaScript, not Rust or TypeScript.

Full details: Generated Files Follow Their Source

Explanation

The pull request changes only crates/zephium-webext-macos/src/compat/compat.js and its test file. It does not change frame/src/shared/ipc/bindings.ts, Cargo.lock, pnpm-lock.yaml, or generated i18n output. No source/generated-file mismatch condition applies.

Full details: Privileged Boundary Intact

Explanation

The authoritative diff contains only compat.js and compat.test.mjs. The production change adds local timer-based requestIdleCallback and cancelIdleCallback functions. It does not add Tauri IPC, a Wry IPC handler, privileged initialization, a custom protocol, CSP or devtools settings, or Rust commands. Therefore none of the stated boundary failures is introduced.

Full details: Performance Impact Stated

Explanation

The change touches startup code. compat.js runs first in every extension context, and the new block adds initialization in non-worker pages and content scripts. The description explains timer and deadline behavior, but it does not state the performance impact of startup initialization or fallback calls, and it gives no performance measurement.

Resolution

Add a Performance Impact section to the PR description. State the added startup work, the per-call timer overhead when the fallback is used, and whether the change affects content-script or extension-page startup. Include measured startup or callback overhead if available.

Finishing Touches

Generate unit tests (beta)

• Create a new PR

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