feat(v8): add competitive node:v8 getHeapSpaceStatistics #25446
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dajneem23
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WalkthroughAdds a new JSC API Changes
Pre-merge checks✅ Passed checks (2 passed)
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🧰 Additional context used🧠 Learnings (29)📓 Common learnings📚 Learning: 2025-11-24T18:36:59.706ZApplied to files:
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📒 Files selected for processing (4)
packages/bun-types/jsc.d.ts(2 hunks)src/bun.js/modules/BunJSCModule.h(4 hunks)src/js/node/v8.ts(1 hunks)test/v8/heap-space-statistics.test.ts(1 hunks)
🧰 Additional context used
📓 Path-based instructions (5)
test/**/*.{js,ts,jsx,tsx}
📄 CodeRabbit inference engine (.cursor/rules/writing-tests.mdc)
test/**/*.{js,ts,jsx,tsx}: Write tests as JavaScript and TypeScript files using Jest-style APIs (test,describe,expect) and import frombun:test
Usetest.eachand data-driven tests to reduce boilerplate when testing multiple similar cases
Files:
test/v8/heap-space-statistics.test.ts
test/**/*.test.{ts,js,jsx,tsx,mjs,cjs}
📄 CodeRabbit inference engine (test/CLAUDE.md)
test/**/*.test.{ts,js,jsx,tsx,mjs,cjs}: Usebun:testwith files that end in*.test.{ts,js,jsx,tsx,mjs,cjs}
Do not write flaky tests. Never wait for time to pass in tests; always wait for the condition to be met instead of using an arbitrary amount of time
Never use hardcoded port numbers in tests. Always useport: 0to get a random port
Prefer concurrent tests over sequential tests usingtest.concurrentordescribe.concurrentwhen multiple tests spawn processes or write files, unless it's very difficult to make them concurrent
When spawning Bun processes in tests, usebunExeandbunEnvfromharnessto ensure the same build of Bun is used and debug logging is silenced
Use-eflag for single-file tests when spawning Bun processes
UsetempDir()from harness to create temporary directories with files for multi-file tests instead of creating files manually
Prefer async/await over callbacks in tests
When callbacks must be used and it's just a single callback, usePromise.withResolversto create a promise that can be resolved or rejected from a callback
Do not set a timeout on tests. Bun already has timeouts
UseBuffer.alloc(count, fill).toString()instead of'A'.repeat(count)to create repetitive strings in tests, as ''.repeat is very slow in debug JavaScriptCore builds
Usedescribeblocks for grouping related tests
Always useawait usingorusingto ensure proper resource cleanup in tests for APIs like Bun.listen, Bun.connect, Bun.spawn, Bun.serve, etc
Always check exit codes and test error scenarios in error tests
Usedescribe.each()for parameterized tests
UsetoMatchSnapshot()for snapshot testing
UsebeforeAll(),afterEach(),beforeEach()for setup/teardown in tests
Track resources (servers, clients) in arrays for cleanup inafterEach()
Files:
test/v8/heap-space-statistics.test.ts
test/**/*.test.{ts,tsx}
📄 CodeRabbit inference engine (CLAUDE.md)
test/**/*.test.{ts,tsx}: For single-file tests in Bun test suite, prefer using-eflag overtempDir
For multi-file tests in Bun test suite, prefer usingtempDirandBun.spawn
Always useport: 0when spawning servers in tests - do not hardcode ports or use custom random port functions
UsenormalizeBunSnapshotto normalize snapshot output in tests instead of manual output comparison
Never write tests that check for no 'panic', 'uncaught exception', or similar strings in test output - that is not a valid test
UsetempDirfromharnessto create temporary directories in tests - do not usetmpdirSyncorfs.mkdtempSync
In tests, callexpect(stdout).toBe(...)beforeexpect(exitCode).toBe(0)when spawning processes for more useful error messages on failure
Do not write flaky tests - do not usesetTimeoutin tests; insteadawaitthe condition to be met since you're testing the CONDITION, not TIME PASSING
Verify your test fails withUSE_SYSTEM_BUN=1 bun test <file>and passes withbun bd test <file>- tests are not valid if they pass withUSE_SYSTEM_BUN=1
Avoid shell commands in tests - do not usefindorgrep; use Bun's Glob and built-in tools instead
Test files must end in.test.tsor.test.tsxand be created in the appropriate test folder structure
Files:
test/v8/heap-space-statistics.test.ts
src/js/{builtins,node,bun,thirdparty,internal}/**/*.{ts,js}
📄 CodeRabbit inference engine (src/js/CLAUDE.md)
src/js/{builtins,node,bun,thirdparty,internal}/**/*.{ts,js}: Use.$call()and.$apply()instead of.call()and.apply()to prevent user tampering with function invocation
Use string literalrequire()statements only; dynamic requires are not permitted
Export modules usingexport default { ... }syntax; modules are NOT ES modules
Use JSC intrinsics (prefixed with$) such as$Array.from(),$isCallable(), and$newArrayWithSize()for performance-critical operations
Use private globals and methods with$prefix (e.g.,$Array,map.$set()) instead of public JavaScript globals
Use$debug()for debug logging and$assert()for assertions; both are stripped in release builds
Validate function arguments using validators frominternal/validatorsand throw$ERR_*error codes for invalid arguments
Useprocess.platformandprocess.archfor platform detection; these values are inlined and dead-code eliminated at build time
Files:
src/js/node/v8.ts
src/js/{builtins,node,bun,thirdparty,internal}/**/*.ts
📄 CodeRabbit inference engine (src/js/CLAUDE.md)
Builtin functions must include
thisparameter typing in TypeScript to enable direct method binding in C++
Files:
src/js/node/v8.ts
🧠 Learnings (41)
📓 Common learnings
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:36:59.706Z
Learning: Applies to src/bun.js/bindings/v8/test/v8/v8.test.ts : Add corresponding test cases to test/v8/v8.test.ts using checkSameOutput() function to compare Node.js and Bun output
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:36:59.706Z
Learning: Applies to src/bun.js/bindings/v8/V8*.cpp : Use JSC::WriteBarrier for heap-allocated references in V8 objects and implement visitChildren() for custom heap objects to support garbage collection
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/js/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:37:11.466Z
Learning: Write JS builtins for Bun's Node.js compatibility and APIs, and run `bun bd` after changes
Learnt from: Jarred-Sumner
Repo: oven-sh/bun PR: 22279
File: test/js/web/structured-clone-fastpath.test.ts:12-12
Timestamp: 2025-08-31T09:08:12.104Z
Learning: In Bun, process.memoryUsage.rss() is called as a direct function, not as process.memoryUsage().rss like in Node.js. This is the correct API shape for Bun.
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/AGENTS.md:0-0
Timestamp: 2025-11-24T18:37:47.899Z
Learning: Applies to src/bun.js/bindings/v8/**/<UNKNOWN> : <UNKNOWN>
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:36:59.706Z
Learning: Applies to src/bun.js/bindings/v8/test/v8/v8-module/main.cpp : Register new V8 API test functions in the Init method using NODE_SET_METHOD with exports object
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/registering-bun-modules.mdc:0-0
Timestamp: 2025-11-24T18:35:39.205Z
Learning: Add tests for new Bun runtime functionality
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:36:59.706Z
Learning: Applies to src/bun.js/bindings/v8/V8*.h : Add BUN_EXPORT visibility attribute to all public V8 API functions to ensure proper symbol export across platforms
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: CLAUDE.md:0-0
Timestamp: 2025-12-02T05:59:51.485Z
Learning: Applies to src/bun.js/bindings/**/*.cpp : Add iso subspaces for C++ JavaScript classes with C++ fields
Learnt from: theshadow27
Repo: oven-sh/bun PR: 23798
File: test/js/bun/http/node-telemetry.test.ts:27-203
Timestamp: 2025-10-19T04:55:33.099Z
Learning: In test/js/bun/http/node-telemetry.test.ts and the Bun.telemetry._node_binding API, after the architecture refactor, the _node_binding interface only contains two methods: handleIncomingRequest(req, res) and handleWriteHead(res, statusCode). The handleRequestFinish hook and other lifecycle hooks were removed during simplification. Both current methods are fully tested.
📚 Learning: 2025-11-24T18:36:59.706Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:36:59.706Z
Learning: Applies to src/bun.js/bindings/v8/test/v8/v8.test.ts : Add corresponding test cases to test/v8/v8.test.ts using checkSameOutput() function to compare Node.js and Bun output
Applied to files:
test/v8/heap-space-statistics.test.tspackages/bun-types/jsc.d.ts
📚 Learning: 2025-11-24T18:36:59.706Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:36:59.706Z
Learning: Ensure V8 API tests compare identical C++ code output between Node.js and Bun through the test suite validation process
Applied to files:
test/v8/heap-space-statistics.test.ts
📚 Learning: 2025-11-24T18:35:08.612Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/dev-server-tests.mdc:0-0
Timestamp: 2025-11-24T18:35:08.612Z
Learning: Applies to test/bake/dev/html.test.ts : Organize HTML tests in html.test.ts for tests relating to HTML files themselves
Applied to files:
test/v8/heap-space-statistics.test.ts
📚 Learning: 2025-11-24T18:35:50.422Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/writing-tests.mdc:0-0
Timestamp: 2025-11-24T18:35:50.422Z
Learning: See `test/harness.ts` for common test utilities and helpers
Applied to files:
test/v8/heap-space-statistics.test.ts
📚 Learning: 2025-11-24T18:36:59.706Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:36:59.706Z
Learning: Applies to src/bun.js/bindings/v8/test/v8/v8-module/main.cpp : Register new V8 API test functions in the Init method using NODE_SET_METHOD with exports object
Applied to files:
test/v8/heap-space-statistics.test.tssrc/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-12-02T05:59:51.485Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: CLAUDE.md:0-0
Timestamp: 2025-12-02T05:59:51.485Z
Learning: Applies to test/**/*.test.{ts,tsx} : For multi-file tests in Bun test suite, prefer using `tempDir` and `Bun.spawn`
Applied to files:
test/v8/heap-space-statistics.test.ts
📚 Learning: 2025-11-24T18:36:59.706Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:36:59.706Z
Learning: Applies to src/bun.js/bindings/v8/test/v8/v8-module/main.cpp : Create test functions in test/v8/v8-module/main.cpp that take FunctionCallbackInfo<Value> parameter, use the test V8 API, print results for comparison with Node.js, and return Undefined
Applied to files:
test/v8/heap-space-statistics.test.ts
📚 Learning: 2025-11-24T18:36:59.706Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:36:59.706Z
Learning: Applies to src/bun.js/bindings/v8/V8*.cpp : Use JSC::WriteBarrier for heap-allocated references in V8 objects and implement visitChildren() for custom heap objects to support garbage collection
Applied to files:
test/v8/heap-space-statistics.test.tssrc/js/node/v8.tspackages/bun-types/jsc.d.tssrc/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:35:08.612Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/dev-server-tests.mdc:0-0
Timestamp: 2025-11-24T18:35:08.612Z
Learning: Applies to test/bake/dev/esm.test.ts : Organize ESM tests in esm.test.ts for tests about various ESM features in development mode
Applied to files:
test/v8/heap-space-statistics.test.ts
📚 Learning: 2025-11-24T18:35:50.422Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/writing-tests.mdc:0-0
Timestamp: 2025-11-24T18:35:50.422Z
Learning: Applies to test/**/*.{js,ts,jsx,tsx} : Write tests as JavaScript and TypeScript files using Jest-style APIs (`test`, `describe`, `expect`) and import from `bun:test`
Applied to files:
test/v8/heap-space-statistics.test.ts
📚 Learning: 2025-10-25T17:20:19.041Z
Learnt from: theshadow27
Repo: oven-sh/bun PR: 24063
File: test/js/bun/telemetry/server-header-injection.test.ts:5-20
Timestamp: 2025-10-25T17:20:19.041Z
Learning: In the Bun telemetry codebase, tests are organized into two distinct layers: (1) Internal API tests in test/js/bun/telemetry/ use numeric InstrumentKind enum values to test Zig↔JS injection points and low-level integration; (2) Public API tests in packages/bun-otel/test/ use string InstrumentKind values ("http", "fetch", etc.) to test the public-facing BunSDK and instrumentation APIs. This separation allows internal tests to use efficient numeric enums for refactoring flexibility while the public API maintains a developer-friendly string-based interface.
Applied to files:
test/v8/heap-space-statistics.test.ts
📚 Learning: 2025-11-24T18:35:39.205Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/registering-bun-modules.mdc:0-0
Timestamp: 2025-11-24T18:35:39.205Z
Learning: Add tests for new Bun runtime functionality
Applied to files:
test/v8/heap-space-statistics.test.ts
📚 Learning: 2025-11-24T18:37:30.259Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: test/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:37:30.259Z
Learning: Unit tests for specific features are organized by module (e.g., `/test/js/bun/`, `/test/js/node/`)
Applied to files:
test/v8/heap-space-statistics.test.ts
📚 Learning: 2025-10-19T02:44:46.354Z
Learnt from: theshadow27
Repo: oven-sh/bun PR: 23798
File: packages/bun-otel/context-propagation.test.ts:1-1
Timestamp: 2025-10-19T02:44:46.354Z
Learning: In the Bun repository, standalone packages under packages/ (e.g., bun-vscode, bun-inspector-protocol, bun-plugin-yaml, bun-plugin-svelte, bun-debug-adapter-protocol, bun-otel) co-locate their tests with package source code using *.test.ts files. This follows standard npm/monorepo patterns. The test/ directory hierarchy (test/js/bun/, test/cli/, test/js/node/) is reserved for testing Bun's core runtime APIs and built-in functionality, not standalone packages.
Applied to files:
test/v8/heap-space-statistics.test.ts
📚 Learning: 2025-11-24T18:36:59.706Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:36:59.706Z
Learning: Applies to src/bun.js/bindings/v8/V8*.h : Add BUN_EXPORT visibility attribute to all public V8 API functions to ensure proper symbol export across platforms
Applied to files:
packages/bun-types/jsc.d.tssrc/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-12-02T05:59:51.485Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: CLAUDE.md:0-0
Timestamp: 2025-12-02T05:59:51.485Z
Learning: Applies to src/bun.js/bindings/**/*.cpp : Add iso subspaces for C++ JavaScript classes with C++ fields
Applied to files:
packages/bun-types/jsc.d.tssrc/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:37:47.899Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/AGENTS.md:0-0
Timestamp: 2025-11-24T18:37:47.899Z
Learning: Applies to src/bun.js/bindings/v8/**/<UNKNOWN> : <UNKNOWN>
Applied to files:
packages/bun-types/jsc.d.ts
📚 Learning: 2025-08-31T09:08:12.104Z
Learnt from: Jarred-Sumner
Repo: oven-sh/bun PR: 22279
File: test/js/web/structured-clone-fastpath.test.ts:12-12
Timestamp: 2025-08-31T09:08:12.104Z
Learning: In Bun, process.memoryUsage.rss() is called as a direct function, not as process.memoryUsage().rss like in Node.js. This is the correct API shape for Bun.
Applied to files:
packages/bun-types/jsc.d.ts
📚 Learning: 2025-11-24T18:36:59.706Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:36:59.706Z
Learning: Applies to src/bun.js/bindings/v8/src/symbols.txt : Add symbol names without leading underscore to src/symbols.txt for each new V8 API method
Applied to files:
packages/bun-types/jsc.d.ts
📚 Learning: 2025-10-19T02:52:37.412Z
Learnt from: theshadow27
Repo: oven-sh/bun PR: 23798
File: packages/bun-otel/tsconfig.json:1-15
Timestamp: 2025-10-19T02:52:37.412Z
Learning: In the Bun repository, packages under packages/ (e.g., bun-otel) can follow a TypeScript-first pattern where package.json exports point directly to .ts files (not compiled .js files). Bun natively runs TypeScript, so consumers import .ts sources directly and receive full type information without needing compiled .d.ts declaration files. For such packages, adding "declaration": true or "outDir" in tsconfig.json is unnecessary and would break the export structure.
<!-- [remove_learning]
ceedde95-980e-4898-a2c6-40ff73913664
Applied to files:
packages/bun-types/jsc.d.ts
📚 Learning: 2025-10-14T04:04:17.132Z
Learnt from: Jarred-Sumner
Repo: oven-sh/bun PR: 23636
File: src/shell/interpreter.zig:672-0
Timestamp: 2025-10-14T04:04:17.132Z
Learning: In Bun's shell interpreter (src/shell/interpreter.zig), the JavaScript garbage collector's memory reporting API only allows reporting extra memory allocation once at object creation time. Therefore, `estimated_size_for_gc` is intentionally set once during initialization and not updated afterward, even though fields like `root_io`, `vm_args_utf8`, and `export_env` may be mutated later. The `estimatedSize()` method returns this cached initial value, while `memoryCost()` computes the size on-demand.
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-12-02T05:59:51.485Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: CLAUDE.md:0-0
Timestamp: 2025-12-02T05:59:51.485Z
Learning: Applies to src/bun.js/bindings/**/*.cpp : Cache structures in ZigGlobalObject for C++ JavaScript classes
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:36:59.706Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:36:59.706Z
Learning: Applies to src/bun.js/bindings/v8/V8*.h : Create V8 class headers with .h extension following the pattern V8ClassName.h that include pragma once, v8.h, V8Local.h, V8Isolate.h, and declare classes extending from Data with BUN_EXPORT static methods
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:35:39.205Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/registering-bun-modules.mdc:0-0
Timestamp: 2025-11-24T18:35:39.205Z
Learning: Applies to src/bun.js/api/BunObject.zig : Implement getter functions in `src/bun.js/api/BunObject.zig` that return your feature, and export them in the `exportAll()` function
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:35:39.205Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/registering-bun-modules.mdc:0-0
Timestamp: 2025-11-24T18:35:39.205Z
Learning: Applies to src/bun.js/bindings/BunObject+exports.h : Add an entry to the `FOR_EACH_GETTER` macro in `src/bun.js/bindings/BunObject+exports.h` when registering new features
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:36:59.706Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:36:59.706Z
Learning: Applies to src/bun.js/bindings/v8/src/napi/napi.zig : For each new V8 C++ method, add both GCC/Clang and MSVC mangled symbol names to the V8API struct in src/napi/napi.zig using extern fn declarations
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:35:25.883Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/javascriptcore-class.mdc:0-0
Timestamp: 2025-11-24T18:35:25.883Z
Learning: Applies to *.cpp : Implement function definitions using `JSC_DEFINE_HOST_FUNCTION` macro, performing type checking with `jsDynamicCast`, throwing this-type errors when type checking fails, and returning encoded JSValue
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:35:25.883Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/javascriptcore-class.mdc:0-0
Timestamp: 2025-11-24T18:35:25.883Z
Learning: Applies to *.cpp : Define properties on the prototype using `JSC_DECLARE_HOST_FUNCTION` for methods and `JSC_DECLARE_CUSTOM_GETTER`/`JSC_DECLARE_CUSTOM_SETTER` for accessors, organized in a const HashTableValue array
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:36:59.706Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:36:59.706Z
Learning: Provide V8-compatible object layouts that inline V8 functions can read by ensuring objects start with tagged pointer to Map at the correct offset
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:36:08.558Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/zig-javascriptcore-classes.mdc:0-0
Timestamp: 2025-11-24T18:36:08.558Z
Learning: Design class bindings with GC-integrated memory management where JSC garbage collection is responsible for tracking and cleaning up objects
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:35:25.883Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/javascriptcore-class.mdc:0-0
Timestamp: 2025-11-24T18:35:25.883Z
Learning: Applies to *.cpp : Implement prototype classes following the pattern: inherit from `JSC::JSNonFinalObject`, implement `create()`, `subspaceFor()`, `createStructure()`, `DECLARE_INFO`, and `finishCreation()` methods
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-10-14T04:04:47.894Z
Learnt from: Jarred-Sumner
Repo: oven-sh/bun PR: 23636
File: src/shell/ParsedShellScript.zig:15-0
Timestamp: 2025-10-14T04:04:47.894Z
Learning: In src/shell/ParsedShellScript.zig, the JavaScript garbage collector's memory reporting API only allows reporting extra memory allocation once at object creation time. Therefore, `estimated_size_for_gc` is intentionally set once during initialization (via `#computeEstimatedSizeForGC()`) and not updated afterward, even though fields like `args`, `export_env`, and `cwd` may be mutated by methods like `setCwd()`, `setEnv()`, and `take()`. The `estimatedSize()` method returns this cached initial value, while `memoryCost()` computes the size on-demand.
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:35:25.883Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/javascriptcore-class.mdc:0-0
Timestamp: 2025-11-24T18:35:25.883Z
Learning: Applies to *.cpp : Implement getter functions using `JSC_DEFINE_CUSTOM_GETTER` macro, performing type checking with `jsDynamicCast`, throwing errors for type mismatches, and returning encoded JSValue
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:35:25.883Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/javascriptcore-class.mdc:0-0
Timestamp: 2025-11-24T18:35:25.883Z
Learning: Applies to *.cpp : To create JavaScript objects from Zig, implement C++ functions following the `Bun__ClassName__toJS(Zig::GlobalObject*, NativeType*)` convention that construct and return the JavaScript object as an encoded JSValue
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:35:25.883Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/javascriptcore-class.mdc:0-0
Timestamp: 2025-11-24T18:35:25.883Z
Learning: Applies to *.zig : In Zig, declare external C++ functions and wrap them in public methods using the convention `extern fn Bun__ClassName__toJS(...)` and `pub fn toJS(...)`
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-10-18T20:50:47.750Z
Learnt from: theshadow27
Repo: oven-sh/bun PR: 23798
File: src/bun.js/telemetry.zig:366-373
Timestamp: 2025-10-18T20:50:47.750Z
Learning: In Bun's Zig codebase (src/bun.js/bindings/JSValue.zig), the JSValue enum uses `.null` (not `.js_null`) for JavaScript's null value. Only `js_undefined` has the `js_` prefix to avoid collision with Zig's built-in `undefined` keyword. The correct enum fields are: `js_undefined`, `null`, `true`, `false`, and `zero`.
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:35:39.205Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/registering-bun-modules.mdc:0-0
Timestamp: 2025-11-24T18:35:39.205Z
Learning: Applies to **/js_*.zig : Use `bun.JSError!JSValue` for proper error propagation in JavaScript bindings
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:36:08.558Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/zig-javascriptcore-classes.mdc:0-0
Timestamp: 2025-11-24T18:36:08.558Z
Learning: Applies to **/*.zig : Use `JSC.markBinding(src())` in finalize methods for debugging purposes before calling `deinit()`
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-09-05T19:49:26.188Z
Learnt from: markovejnovic
Repo: oven-sh/bun PR: 21728
File: src/valkey/js_valkey_functions.zig:852-867
Timestamp: 2025-09-05T19:49:26.188Z
Learning: In Bun’s Zig code, `.js_undefined` is a valid and preferred JSValue literal for “undefined” (e.g., resolving JSPromise). Do not refactor usages to `jsc.JSValue.jsUndefined()`, especially in src/valkey/js_valkey_functions.zig unsubscribe().
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:35:25.883Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/javascriptcore-class.mdc:0-0
Timestamp: 2025-11-24T18:35:25.883Z
Learning: Applies to *.cpp : Expose C++ class constructors to Zig using `extern "C"` functions following the pattern `Bun__JSClassName(Zig::GlobalObject*)` that return the encoded JSValue constructor
Applied to files:
src/bun.js/modules/BunJSCModule.h
🔇 Additional comments (4)
src/js/node/v8.ts (1)
88-97: LGTM!The implementation correctly calls the native
jsc.heapSpaceStats()and maps the camelCase properties to snake_case to match the Node.js v8 API contract.src/bun.js/modules/BunJSCModule.h (1)
399-428: Reasonable V8 compatibility approach.Adding placeholder spaces with zero values provides structural compatibility with V8's
getHeapSpaceStatisticsAPI. Code expecting specific space names will work, though the values won't be meaningful. Consider documenting this behavior in Bun's v8 compatibility notes.test/v8/heap-space-statistics.test.ts (1)
1-26: Consider adding Node.js comparison test for V8 API compatibility.The tests validate the API shape correctly. Based on learnings, V8 API tests should use
checkSameOutput()to compare Node.js and Bun output, ensuring compatibility. Consider adding a test case that compares the structure (e.g., space names returned) between Node.js and Bun.Example addition:
import { checkSameOutput } from "../harness"; test("getHeapSpaceStatistics matches Node.js space names", () => { checkSameOutput("getHeapSpaceStatistics().map(s => s.space_name).sort()"); });⛔ Skipped due to learnings
Learnt from: CR Repo: oven-sh/bun PR: 0 File: src/bun.js/bindings/v8/CLAUDE.md:0-0 Timestamp: 2025-11-24T18:36:59.706Z Learning: Applies to src/bun.js/bindings/v8/test/v8/v8.test.ts : Add corresponding test cases to test/v8/v8.test.ts using checkSameOutput() function to compare Node.js and Bun outputLearnt from: CR Repo: oven-sh/bun PR: 0 File: src/bun.js/bindings/v8/CLAUDE.md:0-0 Timestamp: 2025-11-24T18:36:59.706Z Learning: Ensure V8 API tests compare identical C++ code output between Node.js and Bun through the test suite validation processLearnt from: CR Repo: oven-sh/bun PR: 0 File: .cursor/rules/writing-tests.mdc:0-0 Timestamp: 2025-11-24T18:35:50.422Z Learning: See `test/harness.ts` for common test utilities and helpersLearnt from: theshadow27 Repo: oven-sh/bun PR: 23798 File: test/js/bun/telemetry-server.test.ts:91-100 Timestamp: 2025-10-18T05:23:24.403Z Learning: In the Bun codebase, telemetry tests (test/js/bun/telemetry-*.test.ts) should focus on telemetry API behavior: configure/disable/isEnabled, callback signatures and invocation, request ID correlation, and error handling. HTTP protocol behaviors like status code normalization (e.g., 200 with empty body → 204) should be tested in HTTP server tests (test/js/bun/http/), not in telemetry tests. Keep separation of concerns: telemetry tests verify the telemetry API contract; HTTP tests verify HTTP semantics.Learnt from: CR Repo: oven-sh/bun PR: 0 File: CLAUDE.md:0-0 Timestamp: 2025-12-02T05:59:51.485Z Learning: Applies to test/**/*.test.{ts,tsx} : For multi-file tests in Bun test suite, prefer using `tempDir` and `Bun.spawn`Learnt from: CR Repo: oven-sh/bun PR: 0 File: .cursor/rules/writing-tests.mdc:0-0 Timestamp: 2025-11-24T18:35:50.422Z Learning: Applies to test/**/*.{js,ts,jsx,tsx} : Write tests as JavaScript and TypeScript files using Jest-style APIs (`test`, `describe`, `expect`) and import from `bun:test`Learnt from: CR Repo: oven-sh/bun PR: 0 File: src/bun.js/bindings/v8/CLAUDE.md:0-0 Timestamp: 2025-11-24T18:36:59.706Z Learning: Applies to src/bun.js/bindings/v8/test/v8/v8-module/main.cpp : Create test functions in test/v8/v8-module/main.cpp that take FunctionCallbackInfo<Value> parameter, use the test V8 API, print results for comparison with Node.js, and return UndefinedLearnt from: CR Repo: oven-sh/bun PR: 0 File: .cursor/rules/writing-tests.mdc:0-0 Timestamp: 2025-11-24T18:35:50.422Z Learning: Tests should be located in the `test/` directory, organized by category: `cli/` for CLI tests, `js/` for JavaScript/TypeScript tests (further subdivided into `bun/`, `node/`, `web/`, `third_party/`), `napi/` for N-API tests, `v8/` for V8 C++ API tests, `bundler/` for bundler/transpiler tests, and `regression/issue/[number]` for regression testsLearnt from: CR Repo: oven-sh/bun PR: 0 File: .cursor/rules/dev-server-tests.mdc:0-0 Timestamp: 2025-11-24T18:35:08.612Z Learning: Applies to test/bake/dev/sourcemap.test.ts : Organize source-map tests in sourcemap.test.ts for tests verifying source-maps are correctLearnt from: CR Repo: oven-sh/bun PR: 0 File: .cursor/rules/dev-server-tests.mdc:0-0 Timestamp: 2025-11-24T18:35:08.612Z Learning: Applies to test/bake/dev/esm.test.ts : Organize ESM tests in esm.test.ts for tests about various ESM features in development modeLearnt from: theshadow27 Repo: oven-sh/bun PR: 24063 File: test/js/bun/telemetry/server-header-injection.test.ts:5-20 Timestamp: 2025-10-25T17:20:19.041Z Learning: In the Bun telemetry codebase, tests are organized into two distinct layers: (1) Internal API tests in test/js/bun/telemetry/ use numeric InstrumentKind enum values to test Zig↔JS injection points and low-level integration; (2) Public API tests in packages/bun-otel/test/ use string InstrumentKind values ("http", "fetch", etc.) to test the public-facing BunSDK and instrumentation APIs. This separation allows internal tests to use efficient numeric enums for refactoring flexibility while the public API maintains a developer-friendly string-based interface.Learnt from: CR Repo: oven-sh/bun PR: 0 File: src/bun.js/bindings/v8/CLAUDE.md:0-0 Timestamp: 2025-11-24T18:36:59.706Z Learning: Applies to src/bun.js/bindings/v8/test/v8/v8-module/main.cpp : Register new V8 API test functions in the Init method using NODE_SET_METHOD with exports objectLearnt from: CR Repo: oven-sh/bun PR: 0 File: .cursor/rules/registering-bun-modules.mdc:0-0 Timestamp: 2025-11-24T18:35:39.205Z Learning: Add tests for new Bun runtime functionalityLearnt from: theshadow27 Repo: oven-sh/bun PR: 23798 File: packages/bun-otel/context-propagation.test.ts:1-1 Timestamp: 2025-10-19T02:44:46.354Z Learning: In the Bun repository, standalone packages under packages/ (e.g., bun-vscode, bun-inspector-protocol, bun-plugin-yaml, bun-plugin-svelte, bun-debug-adapter-protocol, bun-otel) co-locate their tests with package source code using *.test.ts files. This follows standard npm/monorepo patterns. The test/ directory hierarchy (test/js/bun/, test/cli/, test/js/node/) is reserved for testing Bun's core runtime APIs and built-in functionality, not standalone packages.packages/bun-types/jsc.d.ts (1)
78-86: The type definitions appear to be correct. Web search confirms that Bun's documentation includes v8.HeapSpaceStatistics with the exact properties shown in this interface (spaceName, spaceSize, spaceUsedSize, spaceAvailableSize, physicalSpaceSize), so the referenced documentation URL is valid.
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🧰 Additional context used
🧠 Learnings (33)
📓 Common learnings
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:36:59.706Z
Learning: Applies to src/bun.js/bindings/v8/test/v8/v8.test.ts : Add corresponding test cases to test/v8/v8.test.ts using checkSameOutput() function to compare Node.js and Bun output
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:36:59.706Z
Learning: Applies to src/bun.js/bindings/v8/V8*.cpp : Use JSC::WriteBarrier for heap-allocated references in V8 objects and implement visitChildren() for custom heap objects to support garbage collection
Learnt from: Jarred-Sumner
Repo: oven-sh/bun PR: 23636
File: src/shell/interpreter.zig:672-0
Timestamp: 2025-10-14T04:04:17.132Z
Learning: In Bun's shell interpreter (src/shell/interpreter.zig), the JavaScript garbage collector's memory reporting API only allows reporting extra memory allocation once at object creation time. Therefore, `estimated_size_for_gc` is intentionally set once during initialization and not updated afterward, even though fields like `root_io`, `vm_args_utf8`, and `export_env` may be mutated later. The `estimatedSize()` method returns this cached initial value, while `memoryCost()` computes the size on-demand.
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: CLAUDE.md:0-0
Timestamp: 2025-12-02T05:59:51.485Z
Learning: Applies to src/bun.js/bindings/**/*.cpp : Cache structures in ZigGlobalObject for C++ JavaScript classes
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/js/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:37:11.466Z
Learning: Write JS builtins for Bun's Node.js compatibility and APIs, and run `bun bd` after changes
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/registering-bun-modules.mdc:0-0
Timestamp: 2025-11-24T18:35:39.205Z
Learning: Applies to **/js_*.zig : Implement proper memory management with reference counting using `ref()`/`deref()` in JavaScript bindings
Learnt from: Jarred-Sumner
Repo: oven-sh/bun PR: 22279
File: test/js/web/structured-clone-fastpath.test.ts:12-12
Timestamp: 2025-08-31T09:08:12.104Z
Learning: In Bun, process.memoryUsage.rss() is called as a direct function, not as process.memoryUsage().rss like in Node.js. This is the correct API shape for Bun.
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/registering-bun-modules.mdc:0-0
Timestamp: 2025-11-24T18:35:39.205Z
Learning: Applies to src/bun.js/api/BunObject.zig : Implement getter functions in `src/bun.js/api/BunObject.zig` that return your feature, and export them in the `exportAll()` function
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: CLAUDE.md:0-0
Timestamp: 2025-12-02T05:59:51.485Z
Learning: Applies to src/bun.js/bindings/**/*.cpp : Add iso subspaces for C++ JavaScript classes with C++ fields
Learnt from: pfgithub
Repo: oven-sh/bun PR: 24273
File: src/bun.js/test/snapshot.zig:19-19
Timestamp: 2025-11-03T20:43:06.996Z
Learning: In Bun's Zig codebase, when storing JSValue objects in collections like ArrayList, use `jsc.Strong.Optional` (not raw JSValue). When adding values, wrap them with `jsc.Strong.Optional.create(value, globalThis)`. In cleanup code, iterate the collection calling `.deinit()` on each Strong.Optional item before calling `.deinit()` on the ArrayList itself. This pattern automatically handles GC protection. See examples in src/bun.js/test/ScopeFunctions.zig and src/bun.js/node/node_cluster_binding.zig.
📚 Learning: 2025-11-24T18:36:59.706Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:36:59.706Z
Learning: Applies to src/bun.js/bindings/v8/V8*.cpp : Use JSC::WriteBarrier for heap-allocated references in V8 objects and implement visitChildren() for custom heap objects to support garbage collection
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:36:59.706Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:36:59.706Z
Learning: Applies to src/bun.js/bindings/v8/V8*.h : Add BUN_EXPORT visibility attribute to all public V8 API functions to ensure proper symbol export across platforms
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-10-14T04:04:17.132Z
Learnt from: Jarred-Sumner
Repo: oven-sh/bun PR: 23636
File: src/shell/interpreter.zig:672-0
Timestamp: 2025-10-14T04:04:17.132Z
Learning: In Bun's shell interpreter (src/shell/interpreter.zig), the JavaScript garbage collector's memory reporting API only allows reporting extra memory allocation once at object creation time. Therefore, `estimated_size_for_gc` is intentionally set once during initialization and not updated afterward, even though fields like `root_io`, `vm_args_utf8`, and `export_env` may be mutated later. The `estimatedSize()` method returns this cached initial value, while `memoryCost()` computes the size on-demand.
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-12-02T05:59:51.485Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: CLAUDE.md:0-0
Timestamp: 2025-12-02T05:59:51.485Z
Learning: Applies to src/bun.js/bindings/**/*.cpp : Cache structures in ZigGlobalObject for C++ JavaScript classes
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:36:59.706Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:36:59.706Z
Learning: Applies to src/bun.js/bindings/v8/src/napi/napi.zig : For each new V8 C++ method, add both GCC/Clang and MSVC mangled symbol names to the V8API struct in src/napi/napi.zig using extern fn declarations
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:36:59.706Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:36:59.706Z
Learning: Applies to src/bun.js/bindings/v8/test/v8/v8-module/main.cpp : Register new V8 API test functions in the Init method using NODE_SET_METHOD with exports object
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:36:59.706Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:36:59.706Z
Learning: Applies to src/bun.js/bindings/v8/V8*.h : Create V8 class headers with .h extension following the pattern V8ClassName.h that include pragma once, v8.h, V8Local.h, V8Isolate.h, and declare classes extending from Data with BUN_EXPORT static methods
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-12-02T05:59:51.485Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: CLAUDE.md:0-0
Timestamp: 2025-12-02T05:59:51.485Z
Learning: Applies to src/bun.js/bindings/**/*.cpp : Add iso subspaces for C++ JavaScript classes with C++ fields
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:35:39.205Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/registering-bun-modules.mdc:0-0
Timestamp: 2025-11-24T18:35:39.205Z
Learning: Applies to src/bun.js/bindings/BunObject+exports.h : Add an entry to the `FOR_EACH_GETTER` macro in `src/bun.js/bindings/BunObject+exports.h` when registering new features
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:35:25.883Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/javascriptcore-class.mdc:0-0
Timestamp: 2025-11-24T18:35:25.883Z
Learning: Applies to *.zig : In Zig, declare external C++ functions and wrap them in public methods using the convention `extern fn Bun__ClassName__toJS(...)` and `pub fn toJS(...)`
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:35:25.883Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/javascriptcore-class.mdc:0-0
Timestamp: 2025-11-24T18:35:25.883Z
Learning: Applies to *.cpp : For classes without Constructor, use `JSC::LazyProperty<JSGlobalObject, Structure>` instead of `JSC::LazyClassStructure` in ZigGlobalObject.h, initialize in `GlobalObject::finishCreation()`, and visit in `GlobalObject::visitChildrenImpl()`
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-03T20:43:06.996Z
Learnt from: pfgithub
Repo: oven-sh/bun PR: 24273
File: src/bun.js/test/snapshot.zig:19-19
Timestamp: 2025-11-03T20:43:06.996Z
Learning: In Bun's Zig codebase, when storing JSValue objects in collections like ArrayList, use `jsc.Strong.Optional` (not raw JSValue). When adding values, wrap them with `jsc.Strong.Optional.create(value, globalThis)`. In cleanup code, iterate the collection calling `.deinit()` on each Strong.Optional item before calling `.deinit()` on the ArrayList itself. This pattern automatically handles GC protection. See examples in src/bun.js/test/ScopeFunctions.zig and src/bun.js/node/node_cluster_binding.zig.
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:35:25.883Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/javascriptcore-class.mdc:0-0
Timestamp: 2025-11-24T18:35:25.883Z
Learning: Applies to *.cpp : If implementing a JavaScript class in C++ with publicly accessible Constructor and Prototype, use three classes: (1) `class Foo : public JSC::DestructibleObject` if there are C++ class members (add destructor), or use `JSC::constructEmptyObject(vm, structure)` and `putDirectOffset` if only JS properties; (2) `class FooPrototype : public JSC::JSNonFinalObject`; (3) `class FooConstructor : public JSC::InternalFunction`
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:35:25.883Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/javascriptcore-class.mdc:0-0
Timestamp: 2025-11-24T18:35:25.883Z
Learning: Applies to *.cpp : For classes, prototypes, and constructors: add `JSC::LazyClassStructure` to ZigGlobalObject.h, initialize in `GlobalObject::finishCreation()`, visit in `GlobalObject::visitChildrenImpl()`, and implement a setup function that creates prototype, constructor, and main class structures
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:35:25.883Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/javascriptcore-class.mdc:0-0
Timestamp: 2025-11-24T18:35:25.883Z
Learning: Applies to *.cpp : Implement prototype classes following the pattern: inherit from `JSC::JSNonFinalObject`, implement `create()`, `subspaceFor()`, `createStructure()`, `DECLARE_INFO`, and `finishCreation()` methods
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:35:25.883Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/javascriptcore-class.mdc:0-0
Timestamp: 2025-11-24T18:35:25.883Z
Learning: Applies to *.cpp : Define properties on the prototype using `JSC_DECLARE_HOST_FUNCTION` for methods and `JSC_DECLARE_CUSTOM_GETTER`/`JSC_DECLARE_CUSTOM_SETTER` for accessors, organized in a const HashTableValue array
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-03T20:40:59.655Z
Learnt from: pfgithub
Repo: oven-sh/bun PR: 24273
File: src/bun.js/bindings/JSValue.zig:545-586
Timestamp: 2025-11-03T20:40:59.655Z
Learning: In Bun's Zig codebase, JSErrors (returned as `bun.JSError!T`) must always be properly handled. Using `catch continue` or `catch { break; }` to silently suppress JSErrors is a bug. Errors should either be explicitly handled or propagated with `try`. This applies to snapshot serializer error handling where Jest's behavior is to throw when serializers throw.
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:35:25.883Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/javascriptcore-class.mdc:0-0
Timestamp: 2025-11-24T18:35:25.883Z
Learning: Applies to *.cpp : Implement function definitions using `JSC_DEFINE_HOST_FUNCTION` macro, performing type checking with `jsDynamicCast`, throwing this-type errors when type checking fails, and returning encoded JSValue
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:35:39.205Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/registering-bun-modules.mdc:0-0
Timestamp: 2025-11-24T18:35:39.205Z
Learning: Applies to **/js_*.zig : Implement proper memory management with reference counting using `ref()`/`deref()` in JavaScript bindings
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:36:59.706Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:36:59.706Z
Learning: Applies to src/bun.js/bindings/v8/src/symbols.txt : Add symbol names without leading underscore to src/symbols.txt for each new V8 API method
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:36:59.706Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:36:59.706Z
Learning: Applies to src/bun.js/bindings/v8/src/symbols.dyn : Add symbol names with leading underscore and semicolons in braces to src/symbols.dyn for each new V8 API method
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-10-14T04:04:47.894Z
Learnt from: Jarred-Sumner
Repo: oven-sh/bun PR: 23636
File: src/shell/ParsedShellScript.zig:15-0
Timestamp: 2025-10-14T04:04:47.894Z
Learning: In src/shell/ParsedShellScript.zig, the JavaScript garbage collector's memory reporting API only allows reporting extra memory allocation once at object creation time. Therefore, `estimated_size_for_gc` is intentionally set once during initialization (via `#computeEstimatedSizeForGC()`) and not updated afterward, even though fields like `args`, `export_env`, and `cwd` may be mutated by methods like `setCwd()`, `setEnv()`, and `take()`. The `estimatedSize()` method returns this cached initial value, while `memoryCost()` computes the size on-demand.
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:36:59.706Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:36:59.706Z
Learning: Provide V8-compatible object layouts that inline V8 functions can read by ensuring objects start with tagged pointer to Map at the correct offset
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:36:08.558Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/zig-javascriptcore-classes.mdc:0-0
Timestamp: 2025-11-24T18:36:08.558Z
Learning: Design class bindings with GC-integrated memory management where JSC garbage collection is responsible for tracking and cleaning up objects
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:35:25.883Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/javascriptcore-class.mdc:0-0
Timestamp: 2025-11-24T18:35:25.883Z
Learning: Applies to *.cpp : Implement getter functions using `JSC_DEFINE_CUSTOM_GETTER` macro, performing type checking with `jsDynamicCast`, throwing errors for type mismatches, and returning encoded JSValue
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:35:25.883Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/javascriptcore-class.mdc:0-0
Timestamp: 2025-11-24T18:35:25.883Z
Learning: Applies to *.cpp : To create JavaScript objects from Zig, implement C++ functions following the `Bun__ClassName__toJS(Zig::GlobalObject*, NativeType*)` convention that construct and return the JavaScript object as an encoded JSValue
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-10-18T20:50:47.750Z
Learnt from: theshadow27
Repo: oven-sh/bun PR: 23798
File: src/bun.js/telemetry.zig:366-373
Timestamp: 2025-10-18T20:50:47.750Z
Learning: In Bun's Zig codebase (src/bun.js/bindings/JSValue.zig), the JSValue enum uses `.null` (not `.js_null`) for JavaScript's null value. Only `js_undefined` has the `js_` prefix to avoid collision with Zig's built-in `undefined` keyword. The correct enum fields are: `js_undefined`, `null`, `true`, `false`, and `zero`.
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:35:39.205Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/registering-bun-modules.mdc:0-0
Timestamp: 2025-11-24T18:35:39.205Z
Learning: Applies to **/js_*.zig : Use `bun.JSError!JSValue` for proper error propagation in JavaScript bindings
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:36:08.558Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/zig-javascriptcore-classes.mdc:0-0
Timestamp: 2025-11-24T18:36:08.558Z
Learning: Applies to **/*.zig : Use `JSC.markBinding(src())` in finalize methods for debugging purposes before calling `deinit()`
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-09-05T19:49:26.188Z
Learnt from: markovejnovic
Repo: oven-sh/bun PR: 21728
File: src/valkey/js_valkey_functions.zig:852-867
Timestamp: 2025-09-05T19:49:26.188Z
Learning: In Bun’s Zig code, `.js_undefined` is a valid and preferred JSValue literal for “undefined” (e.g., resolving JSPromise). Do not refactor usages to `jsc.JSValue.jsUndefined()`, especially in src/valkey/js_valkey_functions.zig unsubscribe().
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:35:25.883Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/javascriptcore-class.mdc:0-0
Timestamp: 2025-11-24T18:35:25.883Z
Learning: Applies to *.cpp : Expose C++ class constructors to Zig using `extern "C"` functions following the pattern `Bun__JSClassName(Zig::GlobalObject*)` that return the encoded JSValue constructor
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:35:39.205Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/registering-bun-modules.mdc:0-0
Timestamp: 2025-11-24T18:35:39.205Z
Learning: Applies to src/bun.js/api/BunObject.zig : Implement getter functions in `src/bun.js/api/BunObject.zig` that return your feature, and export them in the `exportAll()` function
Applied to files:
src/bun.js/modules/BunJSCModule.h
🔇 Additional comments (3)
src/bun.js/modules/BunJSCModule.h (3)
1006-1006: LGTM!The lookup table entry is correctly formatted with the full function name and proper
Function 0suffix.
1035-1035: LGTM!Module version correctly incremented to reflect the new export.
1047-1047: LGTM!Function correctly registered in the native module exports.
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🧰 Additional context used
🧠 Learnings (36)
📓 Common learnings
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:36:59.706Z
Learning: Applies to src/bun.js/bindings/v8/test/v8/v8.test.ts : Add corresponding test cases to test/v8/v8.test.ts using checkSameOutput() function to compare Node.js and Bun output
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:36:59.706Z
Learning: Applies to src/bun.js/bindings/v8/V8*.cpp : Use JSC::WriteBarrier for heap-allocated references in V8 objects and implement visitChildren() for custom heap objects to support garbage collection
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:36:59.706Z
Learning: Applies to src/bun.js/bindings/v8/test/v8/v8-module/main.cpp : Register new V8 API test functions in the Init method using NODE_SET_METHOD with exports object
📚 Learning: 2025-11-24T18:36:59.706Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:36:59.706Z
Learning: Applies to src/bun.js/bindings/v8/V8*.cpp : Use JSC::WriteBarrier for heap-allocated references in V8 objects and implement visitChildren() for custom heap objects to support garbage collection
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:36:59.706Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:36:59.706Z
Learning: Applies to src/bun.js/bindings/v8/V8*.h : Add BUN_EXPORT visibility attribute to all public V8 API functions to ensure proper symbol export across platforms
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:36:59.706Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:36:59.706Z
Learning: Applies to src/bun.js/bindings/v8/src/napi/napi.zig : For each new V8 C++ method, add both GCC/Clang and MSVC mangled symbol names to the V8API struct in src/napi/napi.zig using extern fn declarations
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-12-02T05:59:51.485Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: CLAUDE.md:0-0
Timestamp: 2025-12-02T05:59:51.485Z
Learning: Applies to src/bun.js/bindings/**/*.cpp : Cache structures in ZigGlobalObject for C++ JavaScript classes
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:36:59.706Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:36:59.706Z
Learning: Applies to src/bun.js/bindings/v8/V8*.h : Create V8 class headers with .h extension following the pattern V8ClassName.h that include pragma once, v8.h, V8Local.h, V8Isolate.h, and declare classes extending from Data with BUN_EXPORT static methods
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:36:59.706Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:36:59.706Z
Learning: Applies to src/bun.js/bindings/v8/test/v8/v8-module/main.cpp : Register new V8 API test functions in the Init method using NODE_SET_METHOD with exports object
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-12-02T05:59:51.485Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: CLAUDE.md:0-0
Timestamp: 2025-12-02T05:59:51.485Z
Learning: Applies to src/bun.js/bindings/**/*.cpp : Add iso subspaces for C++ JavaScript classes with C++ fields
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-10-14T04:04:17.132Z
Learnt from: Jarred-Sumner
Repo: oven-sh/bun PR: 23636
File: src/shell/interpreter.zig:672-0
Timestamp: 2025-10-14T04:04:17.132Z
Learning: In Bun's shell interpreter (src/shell/interpreter.zig), the JavaScript garbage collector's memory reporting API only allows reporting extra memory allocation once at object creation time. Therefore, `estimated_size_for_gc` is intentionally set once during initialization and not updated afterward, even though fields like `root_io`, `vm_args_utf8`, and `export_env` may be mutated later. The `estimatedSize()` method returns this cached initial value, while `memoryCost()` computes the size on-demand.
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:35:39.205Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/registering-bun-modules.mdc:0-0
Timestamp: 2025-11-24T18:35:39.205Z
Learning: Applies to src/bun.js/bindings/BunObject+exports.h : Add an entry to the `FOR_EACH_GETTER` macro in `src/bun.js/bindings/BunObject+exports.h` when registering new features
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:37:47.899Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/AGENTS.md:0-0
Timestamp: 2025-11-24T18:37:47.899Z
Learning: Applies to src/bun.js/bindings/v8/**/<UNKNOWN> : <UNKNOWN>
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:36:59.706Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:36:59.706Z
Learning: Applies to src/bun.js/bindings/v8/src/symbols.txt : Add symbol names without leading underscore to src/symbols.txt for each new V8 API method
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:36:59.706Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:36:59.706Z
Learning: Applies to src/bun.js/bindings/v8/src/symbols.dyn : Add symbol names with leading underscore and semicolons in braces to src/symbols.dyn for each new V8 API method
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-03T20:43:06.996Z
Learnt from: pfgithub
Repo: oven-sh/bun PR: 24273
File: src/bun.js/test/snapshot.zig:19-19
Timestamp: 2025-11-03T20:43:06.996Z
Learning: In Bun's Zig codebase, when storing JSValue objects in collections like ArrayList, use `jsc.Strong.Optional` (not raw JSValue). When adding values, wrap them with `jsc.Strong.Optional.create(value, globalThis)`. In cleanup code, iterate the collection calling `.deinit()` on each Strong.Optional item before calling `.deinit()` on the ArrayList itself. This pattern automatically handles GC protection. See examples in src/bun.js/test/ScopeFunctions.zig and src/bun.js/node/node_cluster_binding.zig.
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:35:25.883Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/javascriptcore-class.mdc:0-0
Timestamp: 2025-11-24T18:35:25.883Z
Learning: Applies to *.cpp : Implement prototype classes following the pattern: inherit from `JSC::JSNonFinalObject`, implement `create()`, `subspaceFor()`, `createStructure()`, `DECLARE_INFO`, and `finishCreation()` methods
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:36:59.706Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:36:59.706Z
Learning: Applies to src/bun.js/bindings/v8/V8*.cpp : Use isolate->currentHandleScope()->createLocal<T>() to create local V8 handles and ensure all V8 values are created within an active handle scope
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-12-02T05:59:51.485Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: CLAUDE.md:0-0
Timestamp: 2025-12-02T05:59:51.485Z
Learning: Applies to src/bun.js/bindings/**/*.cpp : JavaScript class implementations in C++ should create three classes if there's a public constructor: `Foo` (JSDestructibleObject), `FooPrototype` (JSNonFinalObject), and `FooConstructor` (InternalFunction)
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:35:25.883Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/javascriptcore-class.mdc:0-0
Timestamp: 2025-11-24T18:35:25.883Z
Learning: Applies to *.cpp : For classes without Constructor, use `JSC::LazyProperty<JSGlobalObject, Structure>` instead of `JSC::LazyClassStructure` in ZigGlobalObject.h, initialize in `GlobalObject::finishCreation()`, and visit in `GlobalObject::visitChildrenImpl()`
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:35:25.883Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/javascriptcore-class.mdc:0-0
Timestamp: 2025-11-24T18:35:25.883Z
Learning: Applies to *.cpp : If implementing a JavaScript class in C++ with publicly accessible Constructor and Prototype, use three classes: (1) `class Foo : public JSC::DestructibleObject` if there are C++ class members (add destructor), or use `JSC::constructEmptyObject(vm, structure)` and `putDirectOffset` if only JS properties; (2) `class FooPrototype : public JSC::JSNonFinalObject`; (3) `class FooConstructor : public JSC::InternalFunction`
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:35:25.883Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/javascriptcore-class.mdc:0-0
Timestamp: 2025-11-24T18:35:25.883Z
Learning: Applies to *.cpp : For classes, prototypes, and constructors: add `JSC::LazyClassStructure` to ZigGlobalObject.h, initialize in `GlobalObject::finishCreation()`, visit in `GlobalObject::visitChildrenImpl()`, and implement a setup function that creates prototype, constructor, and main class structures
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:36:59.706Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:36:59.706Z
Learning: Applies to src/bun.js/bindings/v8/V8*.cpp : Create V8 class implementations with .cpp extension following the pattern V8ClassName.cpp that include the header, v8_compatibility_assertions.h, use ASSERT_V8_TYPE_LAYOUT_MATCHES macro, and implement methods using isolate->currentHandleScope()->createLocal<T>() for handle creation
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:36:59.706Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:36:59.706Z
Learning: Applies to src/bun.js/bindings/v8/V8*.cpp : Use localToJSValue() to convert V8 handles to JSC values and perform JSC operations within V8 method implementations
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:35:25.883Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/javascriptcore-class.mdc:0-0
Timestamp: 2025-11-24T18:35:25.883Z
Learning: Applies to *.cpp : Implement function definitions using `JSC_DEFINE_HOST_FUNCTION` macro, performing type checking with `jsDynamicCast`, throwing this-type errors when type checking fails, and returning encoded JSValue
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:35:25.883Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/javascriptcore-class.mdc:0-0
Timestamp: 2025-11-24T18:35:25.883Z
Learning: Applies to *.cpp : Define properties on the prototype using `JSC_DECLARE_HOST_FUNCTION` for methods and `JSC_DECLARE_CUSTOM_GETTER`/`JSC_DECLARE_CUSTOM_SETTER` for accessors, organized in a const HashTableValue array
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-10-14T04:04:47.894Z
Learnt from: Jarred-Sumner
Repo: oven-sh/bun PR: 23636
File: src/shell/ParsedShellScript.zig:15-0
Timestamp: 2025-10-14T04:04:47.894Z
Learning: In src/shell/ParsedShellScript.zig, the JavaScript garbage collector's memory reporting API only allows reporting extra memory allocation once at object creation time. Therefore, `estimated_size_for_gc` is intentionally set once during initialization (via `#computeEstimatedSizeForGC()`) and not updated afterward, even though fields like `args`, `export_env`, and `cwd` may be mutated by methods like `setCwd()`, `setEnv()`, and `take()`. The `estimatedSize()` method returns this cached initial value, while `memoryCost()` computes the size on-demand.
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:36:59.706Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: src/bun.js/bindings/v8/CLAUDE.md:0-0
Timestamp: 2025-11-24T18:36:59.706Z
Learning: Provide V8-compatible object layouts that inline V8 functions can read by ensuring objects start with tagged pointer to Map at the correct offset
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:36:08.558Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/zig-javascriptcore-classes.mdc:0-0
Timestamp: 2025-11-24T18:36:08.558Z
Learning: Design class bindings with GC-integrated memory management where JSC garbage collection is responsible for tracking and cleaning up objects
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:35:25.883Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/javascriptcore-class.mdc:0-0
Timestamp: 2025-11-24T18:35:25.883Z
Learning: Applies to *.cpp : Implement getter functions using `JSC_DEFINE_CUSTOM_GETTER` macro, performing type checking with `jsDynamicCast`, throwing errors for type mismatches, and returning encoded JSValue
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:35:25.883Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/javascriptcore-class.mdc:0-0
Timestamp: 2025-11-24T18:35:25.883Z
Learning: Applies to *.cpp : To create JavaScript objects from Zig, implement C++ functions following the `Bun__ClassName__toJS(Zig::GlobalObject*, NativeType*)` convention that construct and return the JavaScript object as an encoded JSValue
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:35:25.883Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/javascriptcore-class.mdc:0-0
Timestamp: 2025-11-24T18:35:25.883Z
Learning: Applies to *.zig : In Zig, declare external C++ functions and wrap them in public methods using the convention `extern fn Bun__ClassName__toJS(...)` and `pub fn toJS(...)`
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-10-18T20:50:47.750Z
Learnt from: theshadow27
Repo: oven-sh/bun PR: 23798
File: src/bun.js/telemetry.zig:366-373
Timestamp: 2025-10-18T20:50:47.750Z
Learning: In Bun's Zig codebase (src/bun.js/bindings/JSValue.zig), the JSValue enum uses `.null` (not `.js_null`) for JavaScript's null value. Only `js_undefined` has the `js_` prefix to avoid collision with Zig's built-in `undefined` keyword. The correct enum fields are: `js_undefined`, `null`, `true`, `false`, and `zero`.
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:35:39.205Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/registering-bun-modules.mdc:0-0
Timestamp: 2025-11-24T18:35:39.205Z
Learning: Applies to **/js_*.zig : Use `bun.JSError!JSValue` for proper error propagation in JavaScript bindings
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:36:08.558Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/zig-javascriptcore-classes.mdc:0-0
Timestamp: 2025-11-24T18:36:08.558Z
Learning: Applies to **/*.zig : Use `JSC.markBinding(src())` in finalize methods for debugging purposes before calling `deinit()`
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-09-05T19:49:26.188Z
Learnt from: markovejnovic
Repo: oven-sh/bun PR: 21728
File: src/valkey/js_valkey_functions.zig:852-867
Timestamp: 2025-09-05T19:49:26.188Z
Learning: In Bun’s Zig code, `.js_undefined` is a valid and preferred JSValue literal for “undefined” (e.g., resolving JSPromise). Do not refactor usages to `jsc.JSValue.jsUndefined()`, especially in src/valkey/js_valkey_functions.zig unsubscribe().
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:35:25.883Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/javascriptcore-class.mdc:0-0
Timestamp: 2025-11-24T18:35:25.883Z
Learning: Applies to *.cpp : Expose C++ class constructors to Zig using `extern "C"` functions following the pattern `Bun__JSClassName(Zig::GlobalObject*)` that return the encoded JSValue constructor
Applied to files:
src/bun.js/modules/BunJSCModule.h
📚 Learning: 2025-11-24T18:35:39.205Z
Learnt from: CR
Repo: oven-sh/bun PR: 0
File: .cursor/rules/registering-bun-modules.mdc:0-0
Timestamp: 2025-11-24T18:35:39.205Z
Learning: Applies to src/bun.js/api/BunObject.zig : Implement getter functions in `src/bun.js/api/BunObject.zig` that return your feature, and export them in the `exportAll()` function
Applied to files:
src/bun.js/modules/BunJSCModule.h
🔇 Additional comments (2)
src/bun.js/modules/BunJSCModule.h (2)
1005-1007: LUT entry correctly wiresheapSpaceStatsto the new host function.The BunJSC module table now exposes
heapSpaceStatsmapped tofunctionHeapSpaceStatisticswithFunction 0, matching the surrounding entries and the new host function name. No issues here.
1035-1048: Native module version bump and export wiring look consistent.
INIT_NATIVE_MODULE(37);properly bumps the version, andputNativeFn("heapSpaceStats", functionHeapSpaceStatistics)aligns with the LUT and the declared/defined host function. This should make the new API available to Zig/JS callers without breaking existing exports.
dajneem23
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What does this PR do?
Add implementation for v8:getHeapSpaceStatistics, JSC doesn't have spaces like v8, so I added placeholder spaces to make it compatible with v8:getHeapSpaceStatistics
How did you verify your code works?
Verification
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