Iterative Retrieval

---
name: iterative-retrieval
description: Progressively refine codebase and evidence retrieval for agents using dispatch, evaluation, query refinement, and bounded iteration. Use when a task spans unfamiliar modules, initial context is incomplete or noisy, an agent reports missing context, or parallel workers need compact evidence packets.
---

# Iterative Retrieval Pattern

Solve the context problem in multi-agent workflows where agents do not know what evidence they need until investigation begins.

## When to Activate

- Spawning subagents that need codebase context they cannot predict upfront
- Building multi-agent workflows where context is progressively refined
- Encountering "context too large" or "missing context" failures in agent tasks
- Designing RAG-like retrieval pipelines for code exploration
- Optimizing token usage in agent orchestration

## The Problem

Subagents are spawned with limited context. They don't know:
- Which files contain relevant code
- What patterns exist in the codebase
- What terminology the project uses

Standard approaches fail:
- **Send everything**: Exceeds context limits
- **Send nothing**: Agent lacks critical information
- **Guess what's needed**: Often wrong

## The Solution: Iterative Retrieval

A 4-phase loop that progressively refines context:

```
┌─────────────────────────────────────────────┐
│                                             │
│   ┌──────────┐      ┌──────────┐            │
│   │ DISPATCH │─────│ EVALUATE │            │
│   └──────────┘      └──────────┘            │
│        ▲                  │                 │
│        │                  ▼                 │
│   ┌──────────┐      ┌──────────┐            │
│   │   LOOP   │─────│  REFINE  │            │
│   └──────────┘      └──────────┘            │
│                                             │
│        Max 3 cycles, then proceed           │
└─────────────────────────────────────────────┘
```

### Phase 1: DISPATCH

Initial broad query to gather candidate files:

```javascript
// Start with high-level intent
const initialQuery = {
  patterns: ['src/**/*.ts', 'lib/**/*.ts'],
  keywords: ['authentication', 'user', 'session'],
  excludes: ['*.test.ts', '*.spec.ts']
};

// Dispatch to retrieval agent
const candidates = await retrieveFiles(initialQuery);
```

### Phase 2: EVALUATE

Assess retrieved content for relevance:

```javascript
function evaluateRelevance(files, task) {
  return files.map(file => ({
    path: file.path,
    relevance: scoreRelevance(file.content, task),
    reason: explainRelevance(file.content, task),
    missingContext: identifyGaps(file.content, task)
  }));
}
```

Scoring criteria:
- **High (0.8-1.0)**: Directly implements target functionality
- **Medium (0.5-0.79)**: Contains related patterns or types
- **Low (0.2-0.49)**: Tangentially related
- **None (0-0.19)**: Not relevant, exclude

### Phase 3: REFINE

Update search criteria based on evaluation:

```javascript
function refineQuery(evaluation, previousQuery) {
  return {
    // Add new patterns discovered in high-relevance files
    patterns: [...previousQuery.patterns, ...extractPatterns(evaluation)],

    // Add terminology found in codebase
    keywords: [...previousQuery.keywords, ...extractKeywords(evaluation)],

    // Exclude confirmed irrelevant paths
    excludes: [...previousQuery.excludes, ...evaluation
      .filter(e => e.relevance < 0.2)
      .map(e => e.path)
    ],

    // Target specific gaps
    focusAreas: evaluation
      .flatMap(e => e.missingContext)
      .filter(unique)
  };
}
```

### Phase 4: LOOP

Repeat with refined criteria (max 3 cycles):

```javascript
async function iterativeRetrieve(task, maxCycles = 3) {
  let query = createInitialQuery(task);
  let bestContext = [];

  for (let cycle = 0; cycle < maxCycles; cycle++) {
    const candidates = await retrieveFiles(query);
    const evaluation = evaluateRelevance(candidates, task);

    const highRelevance = evaluation.filter(e => e.relevance >= 0.8);
    bestContext = mergeContext(bestContext, highRelevance);

    // Stop when the merged evidence is sufficient, not just the current cycle.
    if (bestContext.length >= 2 && !hasCriticalGaps(bestContext)) {
      return bestContext;
    }

    // Refine and continue
    query = refineQuery(evaluation, query);
  }

  return bestContext;
}
```

## Practical Examples

### Example 1: Bug Fix Context

```
Task: "Fix the authentication token expiry bug"

Cycle 1:
  DISPATCH: Search for "token", "auth", "expiry" in src/**
  EVALUATE: Found auth.ts (0.9), tokens.ts (0.8), user.ts (0.3)
  REFINE: Add "refresh", "jwt" keywords; exclude user.ts

Cycle 2:
  DISPATCH: Search refined terms
  EVALUATE: Found session-manager.ts (0.95), jwt-utils.ts (0.85)
  REFINE: Sufficient context (2 high-relevance files)

Result: auth.ts, tokens.ts, session-manager.ts, jwt-utils.ts
```

### Example 2: Feature Implementation

```
Task: "Add rate limiting to API endpoints"

Cycle 1:
  DISPATCH: Search "rate", "limit", "api" in routes/**
  EVALUATE: No matches - codebase uses "throttle" terminology
  REFINE: Add "throttle", "middleware" keywords

Cycle 2:
  DISPATCH: Search refined terms
  EVALUATE: Found throttle.ts (0.9), middleware/index.ts (0.8)
  REFINE: Need router patterns

Cycle 3:
  DISPATCH: Search "router", "express" patterns
  EVALUATE: Found router-setup.ts (0.8)
  REFINE: Sufficient context

Result: throttle.ts, middleware/index.ts, router-setup.ts
```

## Integration with Codex Agents

Give each Codex worker an evidence packet instead of the full parent transcript. Use native Codex agent dispatch only when delegation is permitted by the user or project instructions.

Use this block in an agent task:

```markdown
When retrieving context for this task:
1. Start with broad keyword search
2. Evaluate each file's relevance (0-1 scale)
3. Identify what context is still missing
4. Refine search criteria and repeat (max 3 cycles)
5. Return files with relevance >= 0.8
```

## Best Practices

1. **Start broad, narrow progressively** - Don't over-specify initial queries
2. **Learn codebase terminology** - First cycle often reveals naming conventions
3. **Track what's missing** - Explicit gap identification drives refinement
4. **Stop at "good enough"** - 3 high-relevance files beats 10 mediocre ones
5. **Exclude confidently** - Low-relevance files won't become relevant

## Related

- `native-agent-swarms` skill - For safe parallel dispatch and synthesis
- `context-engineering` skill - For selecting durable and task-local context
- Source adapted from Everything Claude Code at commit `0f84c0e2796703fbda87d577b2636351418c7442` (MIT)