Decision Logger: Complete Audit Trail for All Decisions

What This Is

A tool that logs every decision you make, why you made it, and how you verified it works.

The Purpose

Code history tells you WHAT changed. Decision logs tell you WHY it changed.

When you return to code months later, you need more than git diff. You need:

• What was decided
• Why that decision was made
• What alternatives were considered
• How it was verified
• When the decision was made

Decision Log Format

Every entry is recorded as JSON:

{
  "timestamp": "2026-04-19T14:30:00Z",
  "decision_id": "DECIDE_001",
  "domain": "architecture",
  "decision": "Use binary tree for state management",
  "problem_context": "Need to handle 2^n possible states with O(log n) lookup",
  "reasoning": "Binary tree enables complete state mapping and efficient traversal",
  "alternatives": {
    "option_1": "Array - simple but O(n) lookup",
    "option_2": "Graph - allows cycles but unclear semantics",
    "option_3": "Binary tree - O(log n) lookup, natural for 0,1 branching"
  },
  "decision_chosen": "option_3",
  "verified": true,
  "verification_method": "Traced 3 example inputs through tree, all reached output correctly",
  "verification_date": "2026-04-19T14:35:00Z",
  "confidence_level": "high",
  "dependencies": ["DECIDE_000", "DECIDE_002"],
  "file_references": ["state_manager.py", "binary_tree.py"],
  "status": "active",
  "notes": "This decision enables the 0-error compute model for state logic"
}

How It Works

When You Make a Decision

1. In your thinking, note the decision
2. Log it with the Decision Logger
3. Include: Problem, reasoning, alternatives, verification
4. Timestamp it automatically
5. Link to related files

The Log File

All decisions go to DECISION_LOG.jsonl (JSON Lines format):

• One decision per line
• No size limit
• Human-readable
• Completely searchable

Querying Decisions

Find decisions by:

# Find decisions about state management
grep "state" DECISION_LOG.jsonl

# Find decisions in a date range
grep "2026-04-" DECISION_LOG.jsonl

# Find unverified decisions
grep '"verified": false' DECISION_LOG.jsonl

# Find decisions for a specific file
grep "state_manager.py" DECISION_LOG.jsonl

What Gets Logged

Architecture Decisions

• Overall system design
• Component relationships
• Data flow choices
• State management approach

Technical Decisions

• Algorithm selection
• Data structure choices
• Implementation approach
• Error handling strategy

Framework Decisions

• Which framework applies here
• How to apply framework
• Why this application is correct
• How it was verified

Verification Decisions

• What was tested
• What was verified
• How verification was done
• Why verification is sufficient

Compliance

Every significant decision should be logged:

Before coding:

• ☑︎ Requirement understood
• ☑︎ Architecture decided
• ☑︎ Framework chosen
• ☑︎ Approach verified

During coding:

• ☑︎ Algorithm selected
• ☑︎ Data structure chosen
• ☑︎ Error handling planned
• ☑︎ Tracing/logging approach

After coding:

• ☑︎ Test coverage verified
• ☑︎ All cases handled
• ☑︎ Documentation complete
• ☑︎ Final verification done

Benefits

For you (now):

• Document your reasoning while it’s fresh
• Verify decisions are sound before coding
• Keep alternatives visible
• Know why each choice was made

For you (later):

• Remember why decisions were made
• Understand consequences of changes
• Avoid repeating old mistakes
• Know what was tried

For others:

• Complete decision history
• Reasoning for choices
• Dependencies between decisions
• Verification proof

For the system:

• Complete audit trail
• Legal/regulatory compliance
• Quality assurance evidence
• Process improvement data

Example: Logging a Decision

Situation: You need to decide how to handle missing inputs

Think through it:

• Options: Default value, error, null, skip
• Reasoning: Safety and clarity
• Verification: Trace through happy path and error path

Log it: Enter decision into logger:

Decision: Use error on missing critical input, default on optional
Reasoning: Critical inputs are validation gates, optional have sensible defaults
Alternatives: Errors everywhere (too strict), defaults everywhere (hides problems)
Verified: Traced through 3 test cases, error and default paths both work

Decision automatically logged with timestamp and linked to file.

Complete 0-Error Compute: Introduction