Logic Visualization — Reverse Engineering Phase 2

Convert source code into Mermaid flowcharts with line-number traceability. This skill reads its targets from manifest.json (populated by Phase 1) and processes each component’s methods.

Three Principles

1. Code is Truth

• Document the ACTUAL code flow, not idealized versions
• Include dead code or seemingly redundant logic
• If code appears buggy, document as-is and note in Question List

2. Traceability to Line

• Every node in a Mermaid diagram MUST include a line number: "Action (L{line})"
• If a line number cannot be determined, exclude that node

3. Behavior over Intent

• Focus on observable actions: method calls, DB operations, network I/O, state mutations
• Do NOT add implied steps not present in code

Execution

Step 1: Load Manifest and Determine Targets

Read docs/reverse/{analysis}/manifest.json.

Verify:

• phase1.status is "verified" — if not, report error and stop
• phase1.targets_for_phase2 contains entries

Determine which components to process:

• If component argument is provided, process only that component
• If omitted, process all entries in phase2.remaining
• If phase2.remaining is empty and phase2.completed has entries, all components are done

Set phase2.status to "in_progress" in the manifest.

Detect language from manifest.language and load references/{language}.md if it exists.

Step 2: Read Target Code

For each target component from the manifest:

With Serena:

mcp__serena__find_symbol(
    name_path_pattern="{method_name}",
    relative_path="{file}",
    include_body=true,
    depth=0
)

Without Serena:

• Use Read to load the source file
• Use Grep to locate method boundaries

For each method, identify:

• Control flow: if/else, switch/case, for/while, try/catch
• Data operations: variable assignments, transformations
• Side effects: database operations, network I/O, file I/O, logging, state mutations

Record the line number for each element.

Step 3: Build Flowchart

Mermaid syntax rules (prevent parse errors):

• No special characters in text: use value not 0 not value != 0
• No array/generic syntax: use byte array not byte[]
• No method call parentheses: use Method param1 (L50) not Method(param1)
• No comparison operators in conditions: use |status not OK| not |status != OK|
• No brackets in text: use lastConnect index (L60) not _lastConnect[index]
• Always suffix line numbers: (L{number})

Diagram structure by complexity:

• Simple (< 50 lines): Single flowchart
• Medium (50-150 lines): Flowchart with subgraphs
• Complex (> 150 lines): Multiple diagrams (one per major section)
• If > 30 nodes in a single diagram, split into multiple diagrams

Verify line numbers before finalizing:

1. Re-read source code using Read tool
2. Confirm each line number is accurate
3. If uncertain, use range: (L40-45)

Step 4: Document Side Effects

For each method, catalog:

Database operations:

External communication:

State mutations:

Logging:

Step 5: Generate Output

Write to docs/reverse/{analysis}/02-logic-{component}.md:

# Logic Flow: {component}

**Analysis Date**: {YYYY-MM-DD}
**Source File**: [{file}]({file})
**Target Method**: `{method}` at Line {start}-{end}
**Complexity**: {simple / medium / complex}

## Source Code

**Source**: [{file}:{line}]({file}:{line})

```{language}
// Line {start}-{end} from {file}
{code}

Logic Flowchart

flowchart TD
    ...

Node-to-Line Mapping

Side Effects Summary

{tables from Step 4}

Question List

Suspected Issues

• {description} — {file}:{line}

Unclear Logic

• {description} — {file}:{line}

### Step 6: Update Manifest

After each component is processed:
- Add entry to `phase2.completed`: `{"component": "{name}", "output": "02-logic-{name}.md", "verification": null}`
- Remove from `phase2.remaining`
- Add entry to `phase2.targets_for_phase3`: `{"component": "{name}", "logic_diagram": "02-logic-{name}.md", "source_file": "{file}"}`

After all components are processed:
- Set `phase2.status` to `"completed"`
- Update `updated` timestamp

## Validation Before Completion

- [ ] Every Mermaid node has a line number `(L{num})`
- [ ] No special characters in Mermaid text
- [ ] All line numbers verified against source code
- [ ] Node-to-line mapping table is complete
- [ ] Side effects are documented
- [ ] Mermaid diagram parses without errors
- [ ] manifest.json is updated with completed components and Phase 3 targets

## Prohibited Actions

- Do NOT add nodes for implied logic not in code
- Do NOT simplify or omit bad code — document as-is
- Do NOT use special characters in Mermaid text
- Do NOT guess line numbers — verify or use range
- Do NOT modify source code files