# Implementation Complete: Adaptive Context Management

## ✅ Both Improvements Implemented

### 1. Adaptive Truncation Based on Actual Token Usage

**Location:** `src/gateway/services/AgentService.ts` - `prepareStep` callback

**How it works:**
```typescript
// Calculate ACTUAL token usage from previous steps
const totalPromptTokens = stepOptions.steps.reduce(
  (sum, step) => sum + (step.usage?.promptTokens ?? 0),
  0
);

// Determine pressure level
if (totalPromptTokens < 50K) → Low pressure → Generous limits
if (totalPromptTokens < 100K) → Medium pressure → Moderate limits
if (totalPromptTokens > 100K) → High pressure → Aggressive limits
```

**Adaptive limits:**
```
Low Pressure (<50K tokens):
- Last result: UNLIMITED
- Next 2: 12KB (3000 tokens)
- Next 3: 6KB (1500 tokens)
- Next 5: 3KB (750 tokens)
- Old: 1.5KB (375 tokens)

Medium Pressure (50-100K tokens):
- Last result: UNLIMITED
- Next 2: 8KB (2000 tokens)
- Next 3: 4KB (1000 tokens)
- Next 5: 2KB (500 tokens)
- Old: 1KB (250 tokens)

High Pressure (100-130K tokens):
- Last result: UNLIMITED
- Next 2: 4KB (1000 tokens)
- Next 3: 2KB (500 tokens)
- Next 5: 1KB (250 tokens)
- Old: 500 chars (125 tokens)
```

**Logging:**
```
[prepareStep] Step 5: 45K tokens used, pressure: low
[prepareStep] Step 10: 85K tokens used, pressure: medium
[prepareStep] Step 15: 120K tokens used, pressure: high
```

### 2. Graceful Error Return (Don't Break UI)

**Location:** `src/core/tools/filesystem.ts` - `readFile` function

**How it works:**
When a file is too large (>2000 tokens), instead of hard failing:

```typescript
return {
  success: false,
  error: `File "config.ts" is 5000 tokens (~20KB, 800 lines).

This exceeds context limits and will be heavily truncated, losing important content.

✅ Better approaches:

1. Read incrementally:
   read_file({ path: "config.ts", offset: 1, limit: 100 })
   Then read more sections as needed

2. Search for specific content:
   bash({ command: "grep -A 10 'function_name' config.ts" })
   bash({ command: "grep -A 5 'class MyClass' config.ts" })

3. Use search tool:
   search_files({ path: "src/", pattern: "pattern", filePattern: "*.ts" })

4. Get file structure:
   bash({ command: "grep -E '^(export )?(class|function|interface|type) ' config.ts" })

Choose the approach that best fits what you need to find.`,
  type: "size_warning"
};
```

**Agent sees this error and can:**
- Try again with `offset`/`limit`
- Use bash grep instead
- Use search_files tool
- Get file structure only

**UI doesn't break** - agent handles the error gracefully!

## Example Flow

### Before (Static Limits, UI Breaking)

```
User: "Read all files in src/"

Agent: [calls read_file("large-file.ts")]
Tool: [returns 100KB]
prepareStep: [truncates to 2KB regardless of context state]
Context: Growing fast, no adaptation

Agent: [calls read_file("another-file.ts")]
Tool: [returns 100KB]  
prepareStep: [truncates to 2KB again]
Context: Still growing, 120K tokens now

Agent: [calls read_file("third-file.ts")]
ERROR: context_length_exceeded ❌
UI: BREAKS, conversation dies
```

### After (Adaptive + Graceful Errors)

```
User: "Read all files in src/"

Agent: [calls read_file("large-file.ts")]
Tool: ERROR - "File is 5000 tokens. Try: read_file({ offset: 1, limit: 100 })"
Agent: [calls read_file("large-file.ts", offset: 1, limit: 100)]
Tool: SUCCESS - returns first 100 lines
prepareStep: [40K tokens, low pressure, generous limits]

Agent: [calls read_file("another-file.ts", offset: 1, limit: 100)]
Tool: SUCCESS
prepareStep: [75K tokens, medium pressure, moderate limits]

Agent: [calls read_file("third-file.ts", offset: 1, limit: 100)]
Tool: SUCCESS
prepareStep: [95K tokens, medium pressure, tightening limits]

Agent: "I've read the first 100 lines of each file. Here's what I found..."
Context: 95K tokens, well under limit ✅
UI: Working perfectly ✅
```

## Benefits

### 1. Context Efficiency
- **Automatic adaptation:** System adjusts to available space
- **Smart resource use:** More room = more context
- **Graceful degradation:** Less room = tighter limits

### 2. Agent Intelligence
- **Self-correction:** Agent learns from errors
- **Better strategies:** Forced to use incremental reading
- **No UI breaks:** Errors are handled gracefully

### 3. Observable Behavior
- **Clear logging:** See pressure levels and decisions
- **Debuggable:** Easy to tune thresholds
- **Transparent:** Agent and user both understand state

## Logs to Watch

```bash
# Start app
npm start

# Watch terminal for these logs:
[prepareStep] Step 5: 45K tokens used, pressure: low
[prepareStep] Step 10: 85K tokens used, pressure: medium
[prepareStep] Step 15: 120K tokens used, pressure: high

# And these truncation messages:
[... 8000 chars truncated (tool #2 from end, limit: ~2000 tokens, context: 85K/medium)]
[... 15000 chars truncated (tool #5 from end, limit: ~500 tokens, context: 120K/high)]
```

## Tuning

All thresholds are configurable in one place:

```typescript
// File: src/gateway/services/AgentService.ts
const CONTEXT_PRESSURE_THRESHOLDS = {
  low: 50000,      // Adjust these based on monitoring
  medium: 100000,
  high: 130000,
  critical: 150000 // Abort threshold (onStepFinish)
};
```

## Testing Checklist

- [ ] Start conversation with 10+ file reads
- [ ] Verify logs show increasing pressure levels
- [ ] Verify limits tighten as context fills
- [ ] Try to read large file without offset/limit
- [ ] Verify agent gets helpful error (not hard failure)
- [ ] Verify agent retries with better approach
- [ ] Verify UI never breaks
- [ ] Verify conversation completes successfully
- [ ] Verify final context < 150K tokens

## Files Modified

1. ✅ `src/gateway/services/AgentService.ts` - Adaptive truncation in `prepareStep`
2. ✅ `src/core/tools/filesystem.ts` - Graceful errors in `readFile`
3. ✅ `docs/IMPLEMENTATION_COMPLETE.md` - This documentation
