lv416e/audit-context-building

Deep Context Builder Skill (Ultra-Granular Pure Context Mode)

1. Purpose

This skill governs how Claude thinks during the context-building phase of an audit.

When active, Claude will:

• Perform line-by-line / block-by-block code analysis by default.
• Apply First Principles, 5 Whys, and 5 Hows at micro scale.
• Continuously link insights → functions → modules → entire system.
• Maintain a stable, explicit mental model that evolves with new evidence.
• Identify invariants, assumptions, flows, and reasoning hazards.

This skill defines a structured analysis format (see Example: Function Micro-Analysis below) and runs before the vulnerability-hunting phase.

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2. When to Use This Skill

Use when:

• Deep comprehension is needed before bug or vulnerability discovery.
• You want bottom-up understanding instead of high-level guessing.
• Reducing hallucinations, contradictions, and context loss is critical.
• Preparing for security auditing, architecture review, or threat modeling.

Do not use for:

• Vulnerability findings
• Fix recommendations
• Exploit reasoning
• Severity/impact rating

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3. How This Skill Behaves

When active, Claude will:

• Default to ultra-granular analysis of each block and line.
• Apply micro-level First Principles, 5 Whys, and 5 Hows.
• Build and refine a persistent global mental model.
• Update earlier assumptions when contradicted ("Earlier I thought X; now Y.").
• Periodically anchor summaries to maintain stable context.
• Avoid speculation; express uncertainty explicitly when needed.

Goal: deep, accurate understanding, not conclusions.

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Rationalizations (Do Not Skip)

| Rationalization | Why It's Wrong | Required Action | |-----------------|----------------|-----------------| | "I get the gist" | Gist-level understanding misses edge cases | Line-by-line analysis required | | "This function is simple" | Simple functions compose into complex bugs | Apply 5 Whys anyway | | "I'll remember this invariant" | You won't. Context degrades. | Write it down explicitly | | "External call is probably fine" | External = adversarial until proven otherwise | Jump into code or model as hostile | | "I can skip this helper" | Helpers contain assumptions that propagate | Trace the full call chain | | "This is taking too long" | Rushed context = hallucinated vulnerabilities later | Slow is fast |

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4. Phase 1 — Initial Orientation (Bottom-Up Scan)

Before deep analysis, Claude performs a minimal mapping:

1. Identify major modules/files/contracts.
2. Note obvious public/external entrypoints.
3. Identify likely actors (users, owners, relayers, oracles, other contracts).
4. Identify important storage variables, dicts, state structs, or cells.
5. Build a preliminary structure without assuming behavior.

This establishes anchors for detailed analysis.

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5. Phase 2 — Ultra-Granular Function Analysis (Default Mode)

Every non-trivial function receives full micro analysis.

5.1 Per-Function Microstructure Checklist

For each function:

1. Purpose

   • Why the function exists and its role in the system.

2. Inputs & Assumptions

   • Parameters and implicit inputs (state, sender, env).
   • Preconditions and constraints.

3. Outputs & Effects

   • Return values.
   • State/storage writes.
   • Events/messages.
   • External interactions.

4. Block-by-Block / Line-by-Line Analysis For each logical block:

   • What it does.
   • Why it appears here (ordering logic).
   • What assumptions it relies on.
   • What invariants it establishes or maintains.
   • What later logic depends on it.

   Apply per-block:

   • First Principles
   • 5 Whys
   • 5 Hows

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5.2 Cross-Function & External Flow Analysis

(Full Integration of Jump-Into-External-Code Rule)

When encountering calls, continue the same micro-first analysis across boundaries.

Internal Calls

• Jump into the callee immediately.
• Perform block-by-block analysis of relevant code.
• Track flow of data, assumptions, and invariants: caller → callee → return → caller.
• Note if callee logic behaves differently in this specific call context.

External Calls — Two Cases

Case A — External Call to a Contract Whose Code Exists in the Codebase Treat as an internal call:

• Jump into the target contract/function.
• Continue block-by-block micro-analysis.
• Propagate invariants and assumptions seamlessly.
• Consider edge cases based on the actual code, not a black-box guess.

Case B — External Call Without Available Code (True External / Black Box) Analyze as adversarial:

• Describe payload/value/gas or parameters sent.
• Identify assumptions about the target.
• Consider all outcomes:
  • revert
  • incorrect/strange return values
  • unexpected state changes
  • misbehavior
  • reentrancy (if applicable)

Continuity Rule

Treat the entire call chain as one continuous execution flow. Never reset context. All invariants, assumptions, and data dependencies must propagate across calls.

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5.3 Complete Analysis Example

See FUNCTION_MICRO_ANALYSIS_EXAMPLE.md for a complete walkthrough demonstrating:

• Full micro-analysis of a DEX swap function
• Application of First Principles, 5 Whys, and 5 Hows
• Block-by-block analysis with invariants and assumptions
• Cross-function dependency mapping
• Risk analysis for external interactions

This example demonstrates the level of depth and structure required for all analyzed functions.

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5.4 Output Requirements

When performing ultra-granular analysis, Claude MUST structure output following the format defined in OUTPUT_REQUIREMENTS.md.

Key requirements:

• Purpose (2-3 sentences minimum)
• Inputs & Assumptions (all parameters, preconditions, trust assumptions)
• Outputs & Effects (returns, state writes, external calls, events, postconditions)
• Block-by-Block Analysis (What, Why here, Assumptions, First Principles/5 Whys/5 Hows)
• Cross-Function Dependencies (internal calls, external calls with risk analysis, shared state)

Quality thresholds:

• Minimum 3 invariants per function
• Minimum 5 assumptions documented
• Minimum 3 risk considerations for external interactions
• At least 1 First Principles application
• At least 3 combined 5 Whys/5 Hows applications

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5.5 Completeness Checklist

Before concluding micro-analysis of a function, verify against the COMPLETENESS_CHECKLIST.md:

• Structural Completeness: All required sections present (Purpose, Inputs, Outputs, Block-by-Block, Dependencies)
• Content Depth: Minimum thresholds met (invariants, assumptions, risk analysis, First Principles)
• Continuity & Integration: Cross-references, propagated assumptions, invariant couplings
• Anti-Hallucination: Line number citations, no vague statements, evidence-based claims

Analysis is complete when all checklist items are satisfied and no unresolved "unclear" items remain.

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6. Phase 3 — Global System Understanding

After sufficient micro-analysis:

1. State & Invariant Reconstruction

   • Map reads/writes of each state variable.
   • Derive multi-function and multi-module invariants.

2. Workflow Reconstruction

   • Identify end-to-end flows (deposit, withdraw, lifecycle, upgrades).
   • Track how state transforms across these flows.
   • Record assumptions that persist across steps.

3. Trust Boundary Mapping

   • Actor → entrypoint → behavior.
   • Identify untrusted input paths.
   • Privilege changes and implicit role expectations.

4. Complexity & Fragility Clustering

   • Functions with many assumptions.
   • High branching logic.
   • Multi-step dependencies.
   • Coupled state changes across modules.

These clusters help guide the vulnerability-hunting phase.

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7. Stability & Consistency Rules

(Anti-Hallucination, Anti-Contradiction)

Claude must:

• Never reshape evidence to fit earlier assumptions. When contradicted:

  • Update the model.
  • State the correction explicitly.

• Periodically anchor key facts Summarize core:

  • invariants
  • state relationships
  • actor roles
  • workflows

• Avoid vague guesses Use:

  • "Unclear; need to inspect X." instead of:
  • "It probably…"

• Cross-reference constantly Connect new insights to previous state, flows, and invariants to maintain global coherence.

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8. Subagent Usage

Claude may spawn subagents for:

• Dense or complex functions.
• Long data-flow or control-flow chains.
• Cryptographic / mathematical logic.
• Complex state machines.
• Multi-module workflow reconstruction.

Use the function-analyzer agent for per-function deep analysis. It follows the full microstructure checklist, cross-function flow rules, and quality thresholds defined in this skill, and enforces the pure-context-building constraint.

Subagents must:

• Follow the same micro-first rules.
• Return summaries that Claude integrates into its global model.

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9. Relationship to Other Phases

This skill runs before:

• Vulnerability discovery
• Classification / triage
• Report writing
• Impact modeling
• Exploit reasoning

It exists solely to build:

• Deep understanding
• Stable context
• System-level clarity

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10. Non-Goals

While active, Claude should NOT:

• Identify vulnerabilities
• Propose fixes
• Generate proofs-of-concept
• Model exploits
• Assign severity or impact

This is pure context building only.