CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

Project Overview

HarmonyOS (鸿蒙) crash diagnostics demo app — com.example.crashdiagnosticsdemo. Targets HarmonyOS 6.1.0 (API 23), Stage Mode, phone devices only. Uses the Hvigor build system with DevEco Studio as the IDE.

Build & Development Commands

This is a HarmonyOS project; use the deveco-cli skill for all build, run, and device operations.

Build (debug): devecocli build or via DevEco Studio
Run on device/emulator: DevEco Studio → Run, or devecocli run
Lint ArkTS: code-linter is configured via code-linter.json5 (triggers on .ets files, enforces security rules like @security/no-unsafe-aes, @security/no-unsafe-hash, etc.)
CLI docs lookup: use the deveco-cli skill to fetch HarmonyOS API docs and samples

Testing

The project includes @ohos/hypium (test framework) and @ohos/hamock (mocking) as dev dependencies. Test targets are configured in entry/build-profile.json5 under the ohosTest target.

Architecture

Entry Point & Page Routing

EntryAbility (entryability/EntryAbility.ets)
  └── loads pages/Index (main page)
        └── navigates to pages/CrashHistory (push route)

EntryAbility initializes CrashDiagnostics on onCreate, sets color mode, and loads pages/Index on onWindowStageCreate.
Page routes are declared in entry/src/main/resources/base/profile/main_pages.json.

Core Diagnostic Layer — `CrashDiagnostics` (diagnostics/CrashDiagnostics.ets)

A static utility class (never instantiated) that is the backbone of the app. Key responsibilities:

HiAppEvent subscription: Registers an hiAppEvent.Watcher named debugCrashWatcher that listens for system APP_CRASH fault events. The watcher is created in initialize() — because it reuses the same name, it picks up un-consumed crash events from a previous process exit on the next launch.
Persistent crash records: Stores up to 10 crash record strings in preferences (key: recent_hiappevent_crash_records). New records are prepended; duplicates are filtered out.
Dismiss-until-new-crash pattern: Tracks which crash the user dismissed (key: dismissed_hiappevent_crash_id). shouldShowLastCrashDialog() returns true only when the current latest crash differs from the dismissed one.
Listener callback: recordsUpdatedListener — a single callback set by the active UI page; fires when cached records change.
Caught error logging: recordCaughtError() logs to hilog only — it does NOT mix caught exceptions into the APP_CRASH history. The history exclusively contains system-generated crash events.

Pages

pages/Index — Main debug screen. Displays crash record count/status, buttons to simulate a caught error (logged only) and a native CPP crash (via NAPI, kills the app), and a button to view crash history. On aboutToAppear, sets itself as the recordsUpdatedListener and optionally shows an alert dialog for the last un-dismissed crash.
pages/CrashHistory — Lists crash records from CrashDiagnostics.getRecentRecords(), with detail view, clear-all, and export-to-ZIP (JSON inside ZIP, saved via DocumentViewPicker).

Native Layer (NAPI)

entry/src/main/cpp/napi_init.cpp  →  libentry.so
entry/src/main/cpp/types/libentry/index.d.ts  →  ArkTS type declarations

Exports a single function simulateCppCrash() that calls std::abort(). Used by pages/Index to demonstrate a native crash that gets picked up by HiAppEvent on the next launch. Built via CMake (CMakeLists.txt) targeting arm64-v8a only, linked against libace_napi.z.so.

Key Data Flow

App crashes (native/JS)
  → HarmonyOS writes APP_CRASH event to HiAppEvent
  → Next app launch: EntryAbility.onCreate → CrashDiagnostics.initialize()
    → hiAppEvent.addWatcher("debugCrashWatcher") picks up events
    → collectFromHolder() formats and caches records to preferences
    → recordsUpdatedListener fires → Index page updates UI
    → Optionally shows AlertDialog for un-dismissed crash

Important Constraints

ArkTS is NOT TypeScript: ArkTS is a strict subset of TypeScript with its own compiler rules. Use the arkts-grammar-standards skill before writing .ets files. Key differences: no any/unknown types in certain contexts, restricted structural typing for @Component structs, specific decorator rules (@State, @Entry, @Component).
Target ABI is arm64-v8a only (no x86_64 emulator support in the build config).
Obfuscation is disabled even in release mode (entry/build-profile.json5).
Strict mode enabled: caseSensitiveCheck: true, useNormalizedOHMUrl: true.

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