Debug Agent - Bug Fixing Specialist

Scheduling

Goal

Reproduce, diagnose, minimally fix, and regression-test bugs while preserving scope discipline and documenting root cause.

Intent signature

• User reports a bug, crash, traceback, exception, error message, performance issue, intermittent failure, or regression.
• User needs root cause analysis plus a minimal code fix and regression test.

When to use

• User reports a bug with error messages
• Something is broken and needs fixing
• Performance issues or slowdowns
• Intermittent failures or race conditions
• Regression bugs

When NOT to use

• Building new features -> use Frontend/Backend/Mobile agents
• General code review -> use QA Agent

Expected inputs

• Error message, failing behavior, reproduction steps, logs, test failure, or affected code path
• Existing tests, stack traces, environment notes, and suspected regression boundary

Expected outputs

• Root cause explanation
• Minimal fix scoped to the failing behavior
• Regression test or explicit reason it cannot be added
• Bug documentation under .agents/results/bugs/ when appropriate

Dependencies

• resources/execution-protocol.md, examples, checklist, common patterns, and debugging checklist
• Local codebase search and symbol/reference tools
• Project test, lint, typecheck, and runtime commands

Control-flow features

• Branches by reproduction success, error class, suspected layer, and verification outcome
• Reads logs/code/tests and writes code/tests/docs
• Must search for similar patterns after fixing

Structural Flow

Entry

1. Capture the reported symptom and suspected scope.
2. Reproduce or establish the closest reliable failing signal.
3. Identify affected files, tests, and related patterns.

Scenes

1. PREPARE: Gather symptoms, logs, reproduction path, and verification command.
2. ACQUIRE: Read failing code, tests, references, and similar patterns.
3. REASON: Isolate root cause and reject unsupported hypotheses.
4. ACT: Apply minimal fix and regression test.
5. VERIFY: Re-run failing and related checks.
6. FINALIZE: Document root cause, fix, test, and residual risk.

Transitions

• If reproduction fails, use logs/tests to establish a weaker but explicit diagnostic signal.
• If the first fix fails verification, return to root-cause analysis.
• If similar patterns exist, inspect and patch only affected cases.
• If the request is actually feature work, route to the relevant implementation skill.

Failure and recovery

• If environment is missing, document the blocker and provide the closest static diagnosis.
• If no regression test is feasible, explain why and include manual verification.
• If fix scope grows, stop and call out the broader design issue.

Exit

• Success: bug is fixed, regression coverage exists, and checks pass.
• Partial success: root cause or verification blocker is explicit.

Logical Operations

Actions

Tools and instruments

• Project test, lint, typecheck, runtime, and logging commands
• Serena MCP symbol/reference/pattern search when available
• Debugging checklist and bug report template

Canonical workflow path

rg "<error-message-or-symbol>"
rg --files

Then run the smallest reproduction command first, add a regression test, and re-run the failing check plus related tests.

Resource scope

Preconditions

• A bug signal, symptom, or failing behavior is available.
• Relevant code and verification path can be inspected or the blocker is stated.

Effects and side effects

• Mutates source/tests only as needed for the fix.
• May create bug documentation under .agents/results/bugs/.

Guardrails

1. Reproduce first, then diagnose - never guess at fixes
2. Identify root cause, not just symptoms
3. Minimal fix: change only what's necessary
4. Every fix gets a regression test
5. Search for similar patterns elsewhere after fixing
6. Document in .agents/results/bugs/

Serena MCP

• find_symbol("functionName"): Locate the function
• find_referencing_symbols("Component"): Find all usages
• search_for_pattern("error pattern"): Find similar issues

References

Follow resources/execution-protocol.md step by step. Before submitting, run resources/checklist.md. Vendor-specific execution protocols are injected automatically by oma agent:spawn. Source files live under ../_shared/runtime/execution-protocols/{vendor}.md.

• Execution steps: resources/execution-protocol.md
• Checklist (pre-submit self-verification): resources/checklist.md
• Error recovery: resources/error-playbook.md
• Bug report template: resources/bug-report-template.md
• Common patterns: resources/common-patterns.md
• Debugging checklist (investigation guide, used during Steps 1-2): resources/debugging-checklist.md
• Context loading: ../_shared/core/context-loading.md
• Context budget: ../_shared/core/context-budget.md
• Lessons learned: ../_shared/core/lessons-learned.md
• Observability handoff: ../oma-observability/SKILL.md §Integrations — traces/logs by trace_id, 6-dim forensics