# Feature Investigation

> > **[IMPORTANT]** Use `TaskCreate` to break ALL work into small tasks BEFORE starting — including tasks for each file read. This prevents context loss from long files. For simple tasks, AI may ask user whether to skip.

- Skill: `diegosouzapw/feature-investigation` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add diegosouzapw/feature-investigation`
- Raw SKILL.md: https://api.skillmd.com/api/skills/diegosouzapw/feature-investigation/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: diegosouzapw (https://skillmd.com/u/diegosouzapw)
- Updated: 2026-09-21
- Page: https://skillmd.com/skills/diegosouzapw/feature-investigation

---


> **[IMPORTANT]** Use `TaskCreate` to break ALL work into small tasks BEFORE starting — including tasks for each file read. This prevents context loss from long files. For simple tasks, AI may ask user whether to skip.

## Quick Summary

**Goal:** Investigate and explain how existing features or logic work through READ-ONLY code exploration -- no modifications.

> **MANDATORY IMPORTANT MUST** Plan ToDo Task to READ the following project-specific reference doc:
>
> - `project-structure-reference.md` -- project patterns and structure
>
> If file not found, search for: project documentation, coding standards, architecture docs.

**Workflow:**

1. **Setup** — Create analysis file, define investigation scope and metadata
2. **Discovery (Phase 1A)** — Glob/Grep to find all relevant files across backend and frontend
3. **Deep Analysis (Phase 1B)** — Read each file, build knowledge graph of relationships
4. **Synthesis (Phase 2)** — Map workflows, integration points, data flows, business logic
5. **Report** — Present findings with evidence chains and code references

**Key Rules:**

- READ-ONLY: never modify code, only explore and explain
- Every claim must have code evidence (no speculation or hallucination)
- Use anti-hallucination protocols: validate assumptions, chain evidence, anchor to original question
- Re-read original question every 10 operations to prevent context drift

> **Skill Variant:** READ-ONLY exploration - no code changes. For implementing features, use `feature-implementation`. For debugging, use `debug`.

# Feature Investigation & Logic Exploration

Investigate and explain how existing features or logic work as an expert full-stack .NET/Angular architect.

**KEY PRINCIPLE**: READ-ONLY investigation. Build understanding and explain how things work.

## Investigation Mindset (NON-NEGOTIABLE)

**Be skeptical. Apply critical thinking. Every claim needs traced proof.**

- Do NOT assume code works as named — verify by reading actual implementations
- Every finding must include `file:line` evidence (grep results, read confirmations)
- If you cannot prove a claim with a code trace, mark it as "inferred" with low confidence
- Question assumptions: "Does this actually do what I think?" → read the implementation, not just the signature
- Challenge completeness: "Is this all?" → grep for related usages, consumers, and cross-service references
- Verify relationships: "Does A really call B?" → trace the actual call path with evidence
- No "looks like it works" without proof — state what you verified and how

## ⚠️ MANDATORY: Confidence & Evidence Gate

**MUST** declare `Confidence: X%` with evidence list + `file:line` proof for EVERY finding.
**95%+** verified fact | **80-94%** with caveats | **60-79%** "partially verified" | **<60% "inferred — needs verification", NOT fact.**

**IMPORTANT**: Always use TaskCreate to plan step-by-step tasks.

---

## Prerequisites

**⚠️ CRITICAL**: Read all protocol sections below before starting investigation.

---

## Anti-Hallucination Protocols

### ASSUMPTION_VALIDATION_CHECKPOINT

Before every major operation:

1. "What assumptions am I making about [X]?"
2. "Have I verified this with actual code evidence?"
3. "Could I be wrong about [specific pattern/relationship]?"

### EVIDENCE_CHAIN_VALIDATION

Before claiming any relationship:

- "I believe X calls Y because..." -> show actual code
- "This follows pattern Z because..." -> cite specific examples
- "Service A owns B because..." -> grep for actual boundaries

### TOOL_EFFICIENCY_PROTOCOL

- Batch multiple Grep searches into single calls with OR patterns
- Use parallel Read operations for related files
- Combine semantic searches with related keywords

### CONTEXT_ANCHOR_SYSTEM

Every 10 operations:

1. Re-read the original question from the `## Metadata` section
2. Verify the current operation aligns with answering the question
3. Check if we're investigating the right thing
4. Update the `Current Focus` bullet point within the `## Progress` section

### Quick Reference Checklist

Before any major operation:

- [ ] ASSUMPTION_VALIDATION_CHECKPOINT
- [ ] EVIDENCE_CHAIN_VALIDATION
- [ ] TOOL_EFFICIENCY_PROTOCOL

Every 10 operations:

- [ ] CONTEXT_ANCHOR_CHECK
- [ ] Update 'Current Focus' in `## Progress` section

Emergency:

- **Context Drift** -> Re-read `## Metadata` section
- **Assumption Creep** -> Halt, validate with code
- **Evidence Gap** -> Mark as "inferred"

---

## Analysis File Structure

Create at `.ai/workspace/analysis/[feature-name]-investigation.analysis.md`:

```markdown
## Metadata

**Original Prompt:** [Full original question/prompt]

**Task Description:** [Parsed investigation question]

**Investigation Scope:** [What needs to be understood]

**Source Code Structure:**

- Backend: services directory/{ServiceA,ServiceB,ServiceC}/
- Frontend: frontend directory/apps/, frontend directory/libs/
- Platform: framework directory/

## Progress

- **Phase**: 1A
- **Items Processed**: 0
- **Total Items**: 0
- **Current Operation**: "initialization"
- **Current Focus**: "[original task summary]"

## Errors

[Track all errors encountered during analysis]

## Assumption Validations

[Document all assumptions and their validation status]

## Performance Metrics

[Track operation times and efficiency]

## Memory Management

[Track context usage and optimization strategies]

## Processed Files

[Numbered list of processed files with status]

## File List

[Complete numbered list of all discovered files - populated during discovery]

## Knowledge Graph

[Detailed analysis of each file - populated during Phase 1B]

## Workflow Analysis

[End-to-end workflow documentation]

## Integration Points

[Cross-service and cross-component integration analysis]

## Business Logic Mapping

[Complete business logic workflows and rules]

## Data Flow Analysis

[How data flows through the system]

## Platform Pattern Usage

[Documentation of platform patterns used]
```

---

## File Discovery Search Patterns

```bash
# Domain Entities (HIGH PRIORITY)
grep: "class.*{EntityName}.*:.*RootEntity|RootAuditedEntity"

# Commands & Queries (HIGH PRIORITY)
grep: ".*Command.*{EntityName}|{EntityName}.*Command"
grep: ".*Query.*{EntityName}|{EntityName}.*Query"

# Event Handlers (HIGH PRIORITY)
grep: ".*EventHandler.*{EntityName}|{EntityName}.*EventHandler"

# Controllers (HIGH PRIORITY)
grep: ".*Controller.*{EntityName}|{EntityName}.*Controller"

# Background Jobs (MEDIUM PRIORITY)
grep: ".*BackgroundJob.*{EntityName}|{EntityName}.*BackgroundJob"

# Message Bus Consumers (MEDIUM PRIORITY)
grep: ".*Consumer.*{EntityName}|{EntityName}.*Consumer"
grep: "PlatformApplicationMessageBusConsumer.*{EntityName}"

# Services & Helpers (LOW PRIORITY)
grep: ".*Service.*{EntityName}|{EntityName}.*Service"
grep: ".*Helper.*{EntityName}|{EntityName}.*Helper"

# Frontend Components & Stores (HIGH PRIORITY)
grep: "{feature-name}" in **/*.{ts,html}
grep: ".*Store.*{FeatureName}|{FeatureName}.*Store"
grep: ".*Component.*{FeatureName}|{FeatureName}.*Component"
```

### File List Organization

```markdown
## File List

### High Priority - Core Logic (MUST ANALYZE FIRST)

1. [Domain Entity path]
2. [Command/Query Handler path]
3. [Event Handler path]
4. [Controller path]
5. [Frontend Component path]
   ...

### Medium Priority - Supporting Infrastructure

10. [Background Job path]
11. [Consumer path]
12. [API Service path]
    ...

### Low Priority - Configuration/Utilities

20. [Helper path]
21. [Utility path]
    ...

**Total Files**: [count]
```

---

## Knowledge Graph Entry Template

For each file, document:

````markdown
### {ItemNumber}. {FilePath}

**File Analysis:**

- **filePath**: Full path to the file
- **type**: Entity | Command | Query | EventHandler | Controller | BackgroundJob | Consumer | Component | Store | Service | Helper
- **architecturalPattern**: CQRS | Repository | Event-Driven | Component-Store | etc.
- **content**: Summary of purpose and logic
- **symbols**: Important classes, interfaces, methods
- **dependencies**: All imported modules or `using` statements
- **businessContext**: What business problem, rules, contribution to feature
- **referenceFiles**: Other files that use this file's symbols
- **relevanceScore**: 1-10 for current investigation
- **evidenceLevel**: "verified" or "inferred"
- **uncertainties**: Aspects you are unsure about
- **platformAbstractions**: Platform base classes used
- **serviceContext**: Which microservice (ServiceB, ServiceA, ServiceC)
- **dependencyInjection**: DI registrations
- **genericTypeParameters**: Generic type relationships

**Message Bus Analysis (FOR CONSUMERS ONLY):**

- **messageBusMessage**: Message type consumed
- **messageBusProducers**: Files that publish this message (MUST grep across ALL services)
- **crossServiceIntegration**: Cross-service data flow description

**Targeted Aspect Analysis:**

**For Frontend Components:**

- `componentHierarchy`, `routeConfig`, `routeGuards`, `stateManagementStores`
- `dataBindingPatterns`, `validationStrategies`, `apiIntegration`, `userInteractionFlow`

**For Backend Components:**

- `authorizationPolicies`, `commands`, `queries`, `domainEntities`
- `repositoryPatterns`, `businessRuleImplementations`, `eventHandlers`, `backgroundJobs`

**For Consumer Components:**

- `messageBusMessage`, `messageBusProducers`, `crossServiceIntegration`
- `handleLogicWorkflow`, `dependencyWaiting`

**Code Examples:**

```csharp
// Include relevant code snippets that demonstrate key logic
```
````

**Key Insights:**

[Important observations about this file's role in the overall feature]

````

---

## Overall Analysis Template

```markdown
## Overall Analysis

### 1. Complete End-to-End Workflows Discovered

**Workflow: {Feature Name} - Main Flow**

````

[User Action] -> [Frontend Component] -> [API Service] -> [Controller]
|
[Command/Query Handler]
|
[Domain Entity] -> [Repository]
|
[Event Handler] -> [Side Effects]

```

**Detailed Flow:**

1. **Frontend Entry Point**: `Component.ts:line` - User interaction, validation, API call
2. **API Layer**: `Controller.cs:line` - Endpoint, authorization, command dispatch
3. **Application Layer**: `CommandHandler.cs:line` - Validation, business logic, repository ops
4. **Domain Layer**: `Entity.cs:line` - Business rules, state changes, domain events
5. **Event Handling**: `EventHandler.cs:line` - Events handled, side effects, integrations
6. **Cross-Service**: `Consumer.cs:line` - Message consumed, producer service, sync logic

### 2. Key Architectural Patterns and Relationships

- **CQRS**: Commands, queries, separation of concerns
- **Event-Driven**: Domain events, handlers, message bus
- **Repository**: Repositories used, query builders, extensions
- **Frontend**: Component hierarchy, state management, forms

### 3. Business Logic Workflows

Frontend-to-backend flow tree and cross-service integration flow.

### 4. Integration Points and Dependencies

API endpoints, message bus integration, database dependencies, external services.

### 5. Business Rules Discovered

Validation rules, business constraints, authorization rules.

### 6. Platform Pattern Usage

Backend: CQRS, repository, event handlers, message bus, background jobs, validation
Frontend: Component hierarchy, stores, forms, API services, reactive patterns

### 7. Key Insights and Observations

Critical findings, recommendations, uncertainties requiring clarification.
```

---

## Presentation Template

```markdown
## Answer

[Direct answer to the question in 1-2 paragraphs]

## How It Works

### 1. [First Step]

[Explanation with code reference at `file:line`]

### 2. [Second Step]

[Explanation with code reference at `file:line`]

## Key Files

| File                  | Purpose   |
| --------------------- | --------- |
| `path/to/file.cs:123` | [Purpose] |

## Data Flow
```

[Text diagram showing the flow]

```

## Want to Know More?

I can explain further:

- [Topic 1]
- [Topic 2]
- [Topic 3]
```

---

## Common Investigation Scenarios

### "How does feature X work?"

1. Find entry points (API, UI, job)
2. Trace through command/query handlers
3. Document entity changes
4. Map side effects (events, notifications)

### "Where is the logic for Y?"

1. Search for keywords in commands, queries, entities
2. Check event handlers for side effect logic
3. Look in helper/service classes
4. Check frontend stores and components

### "What happens when Z occurs?"

1. Identify the trigger (user action, event, schedule)
2. Trace the handler chain
3. Document all side effects
4. Map error handling

### "Why does A behave like B?"

1. Find the relevant code path
2. Identify decision points
3. Check configuration/feature flags
4. Document business rules

---

## Platform-Specific Investigation Patterns

### Backend Patterns to Look For

- `PlatformCqrsCommand` / `PlatformCqrsQuery` - CQRS entry points
- `PlatformCqrsEntityEventApplicationHandler` - Side effects
- `PlatformApplicationMessageBusConsumer` - Cross-service consumers
- `service-specific repository` / `service-specific repository` - Data access
- `PlatformValidationResult` - Validation logic
- `[PlatformAuthorize]` - Authorization

### Frontend Patterns to Look For

- `project store component base (search for: store component base class)` - State management components
- `project store base (search for: store base class)` - Store implementations
- `effectSimple` / `tapResponse` - Effect handling
- `observerLoadingErrorState` - Loading/error states
- API services extending `PlatformApiService`

---

## Investigation Flow

### Phase 1A: Initialize & Discover

1. **Create analysis file** at `.ai/workspace/analysis/[feature-name]-investigation.analysis.md`
    - **Use the Analysis File Structure template** above
2. **Search for all related files** using grep patterns organized by priority
    - **Use the File Discovery Search Patterns** above
3. **Save all discovered paths** as numbered list under `## File List`, organized by priority
4. Update `Total Items` count in `## Progress`

### Phase 1B: Knowledge Graph Construction

1. Count total files, split into batches of 10 (priority order)
2. Insert batch analysis tasks into todo list
3. For each file, document in `## Knowledge Graph`
    - **Use the Knowledge Graph Entry Template** above
4. **Every 10 files**: Update progress, run CONTEXT_ANCHOR_CHECK

### Phase 1C: Overall Analysis

After ALL files analyzed, write comprehensive analysis:

- End-to-end workflows, architectural patterns, business logic
- Integration points, business rules, platform patterns, key insights
- **Use the Overall Analysis Template** above

### Phase 2: Presentation

Present findings in clear format with: Answer, How It Works (with code refs), Key Files table, Data Flow diagram, "Want to Know More?" topics.

- **Use the Presentation Template** above

---

## Anti-Hallucination Protocols (Investigation-Specific)

**Prerequisites:** **MUST READ** `.claude/skills/shared/understand-code-first-protocol.md` and `.claude/skills/shared/evidence-based-reasoning-protocol.md` before executing.

---

## Investigation Guidelines

- **Evidence-based**: Every claim must have code evidence
- **Service boundary awareness**: Understand which service owns what
- **Platform pattern recognition**: Identify platform framework patterns used
- **Cross-service tracing**: Follow message bus flows across services
- **Read-only exploration**: Never suggest changes unless asked
- **Question-focused**: Always tie findings back to the original question
- **Layered explanation**: Start simple, offer deeper detail if requested

---

## See Also

- `feature-implementation` - For implementing new features (code changes)
- `debug` - For debugging and fixing issues
- `planning` - For creating implementation plans

## References

**Note:** All content from `references/investigation-protocols.md` has been merged into this skill file above. The reference file is kept for historical purposes.

| File                                    | Contents                                         |
| --------------------------------------- | ------------------------------------------------ |
| `references/investigation-protocols.md` | (Archived - content merged into this skill file) |

---

## Task Planning Notes

- Always plan and break work into many small todo tasks
- Always add a final review todo task to verify work quality and identify fixes/enhancements