native-runtime-debug

Native Runtime Debugging

Use qwen-dap-mcp to reason from structured debugger evidence instead of guessing from logs. This skill is for software, crash artifacts, and authorized local targets the user owns or is permitted to debug.

Choose the high-level workflow first

Use debug_this_crash for fatal exceptions/signals, invalid memory accesses, aborts, and crash verification. Use debug_this_hang when the process appears stuck, deadlocked, waiting forever, or spinning without useful forward progress.

When a known-good reproduction and a failing/changed reproduction can be stopped at comparable runtime states, use debug_compare_runs before guessing from source. If that comparison identifies a suspicious debugger-visible value and the live target is safe to resume, use debug_trace_value to gather bounded temporal writer evidence.

Do not use a crash-only interpretation for a hang snapshot and do not turn a hang heuristic, static runtime difference, or observed writer into certainty.

Differential and causal debugging

For a known-good versus failing comparison, keep the two runs in different DAP sessions:

debug_sessions(action="create", sessionId="baseline")
debug_sessions(action="create", sessionId="candidate")

Drive each session to the same logical phase using the normal lifecycle or high-level tools, then compare the stopped states:

debug_compare_runs(
  baselineSessionId="baseline",
  candidateSessionId="candidate",
  timeoutMs=30000,
  snapshot={stackLevels:20, maxVariablesPerScope:100, includeModules:true}
)

debug_compare_runs is read-only. Read its result in this order:

1. diff.firstMeaningfulDifference: prioritized semantic difference, not proof of causality.
2. diff.locals: local/argument value changes.
3. diff.exception: exception-state differences.
4. diff.stack: changed call path/frame identity.
5. diff.registers: lower-level register differences.
6. diff.symbolHealth and diff.modules: comparison-quality drift.
7. evidenceBudget: actual bounded capture limits used for both sessions.
8. diff.limitations: explicit interpretation limits.