[FEATURE] Enhanced Verbose/Debug Output Configuration with Resilient Parameter Handling

## Summary

Request for more granular and configurable verbose/debug output options when running Claude Code in GitHub Actions, with resilient parameter handling that gracefully falls back to defaults when options are deprecated or unavailable.

## Current State

### Available Options (claude-code-action v1.0)

| Option | Type | Description |
|--------|------|-------------|
| `show_full_output` | Action Input | Shows full JSON output including tool execution details (default: `false`) |
| `claude_args: --verbose` | CLI Flag | Enables verbose mode with expanded logging |
| `claude_args: --debug` | CLI Flag | Enables debug-level tracing |
| `--output-format stream-json` | CLI Flag | Outputs structured JSON for CI/debugging |
| `ACTIONS_STEP_DEBUG=true` | Env Var | Automatically enables full output in debug mode |

### Known Limitations (from existing issues)

1. **[anthropics/claude-code#4859](https://github.com/anthropics/claude-code/issues/4859)**: `--debug` outputs to stdout instead of stderr; `--verbose` has no effect in print mode
2. **[anthropics/claude-code#6308](https://github.com/anthropics/claude-code/issues/6308)**: All-or-nothing approach - no way to show timing/tokens without full debug logs
3. **[anthropics/claude-code#3217](https://github.com/anthropics/claude-code/issues/3217)** / **[#7012](https://github.com/anthropics/claude-code/issues/7012)**: Verbose setting fails to persist across sessions
4. **[anthropics/claude-code#15066](https://github.com/anthropics/claude-code/issues/15066)**: Hook outputs not appearing in stream-json logs

## Proposed Enhancement

### 1. New Workflow Input Parameters

Add configurable verbosity levels as workflow inputs:

```yaml
- uses: anthropics/claude-code-action@v1
with:
anthropic_api_key: ${{ secrets.ANTHROPIC_API_KEY }}
prompt: "Fix this bug"

# Granular verbosity controls
verbosity: "normal" # Options: minimal | normal | verbose | debug
show_tool_output: true
show_timing: true
show_token_usage: true
log_format: "human" # Options: human | json | stream-json
```

### 2. Environment Variable Configuration

Support configuration via environment variables in the `settings` input:

```yaml
settings: |
{
"env": {
"CLAUDE_VERBOSITY": "verbose",
"CLAUDE_SHOW_TIMING": "true",
"CLAUDE_SHOW_TOKENS": "true"
}
}
```

### 3. Verbosity Levels Definition

| Level | Description | Shows |
|-------|-------------|-------|
| `minimal` | Errors only | Errors, permission denials, final status |
| `normal` | Default behavior | Init, result, errors, summary |
| `verbose` | Detailed execution | + Tool calls, timing, token usage |
| `debug` | Full tracing | + All internal events, JSON output |

## Resilient Parameter Handling (Critical)

**Problem**: When parameters are deprecated or phased out, workflows should not break.

### Proposed Solution: Graceful Degradation Pattern

```typescript
function resolveVerbosity(inputs: ActionInputs): VerbosityConfig {
const warnings: string[] = [];
const config: VerbosityConfig = { level: 'normal' }; // Safe default

// Handle deprecated parameters gracefully
const deprecatedParams = ['old_verbose_flag', 'legacy_debug_mode'];
for (const param of deprecatedParams) {
if (inputs[param] !== undefined) {
warnings.push(`⚠️ Parameter '${param}' is deprecated. Use 'verbosity' instead.`);
}
}

// Validate current parameters with fallback
if (inputs.verbosity) {
const validLevels = ['minimal', 'normal', 'verbose', 'debug'];
if (validLevels.includes(inputs.verbosity)) {
config.level = inputs.verbosity;
} else {
warnings.push(`⚠️ Unknown verbosity level '${inputs.verbosity}'. Falling back to 'normal'.`);
}
}

// Log warnings but don't fail
for (const warning of warnings) {
core.warning(warning);
}

return config;
}
```

### Key Principles

1. **Never fail on unknown/deprecated parameters** - Log warning, use default
2. **Semantic versioning for breaking changes** - Major version bump if behavior changes
3. **Deprecation notices in logs** - Clear messages about what to migrate to
4. **Maintain backwards compatibility** - Old parameters should work until next major version

### Example Warning Output

```
⚠️ Deprecated parameter detected: 'verbose=true'
This parameter will be removed in v2.0.
Migration: Use 'verbosity: verbose' instead.

Falling back to default behavior. Workflow will continue.
```

### Optional: Auto-Report Feature

```yaml
- uses: anthropics/claude-code-action@v1
with:
verbosity: verbose
report_deprecated_params: true # Creates issue if deprecated params used
```

When enabled, could automatically create/update an issue in the user's repo listing deprecated parameters detected.

## Implementation Considerations

### CLI Flag Mapping

```typescript
switch (config.level) {
case 'debug':
cliArgs.push('--debug', '--verbose');
break;
case 'verbose':
cliArgs.push('--verbose');
break;
case 'minimal':
cliArgs.push('--quiet'); // May need new flag
break;
}
```

### Integration with `show_full_output`

```typescript
// show_full_output takes precedence for backwards compatibility
if (inputs.show_full_output === 'true') {
config.level = 'debug';
}
```

## Testing Matrix

| Scenario | Expected Behavior |
|----------|-------------------|
| `verbosity: unknown_value` | Warning + fallback to `normal` |
| `verbose: true` (deprecated) | Warning + map to `verbosity: verbose` |
| No verbosity params | Use `normal` default |
| `ACTIONS_STEP_DEBUG=true` | Override to `debug` (existing behavior) |

## Related Issues

- [anthropics/claude-code#4859](https://github.com/anthropics/claude-code/issues/4859) - Debug/verbose modes not outputting to stderr
- [anthropics/claude-code#6308](https://github.com/anthropics/claude-code/issues/6308) - Timing/tokens without verbose logs
- [anthropics/claude-code#3217](https://github.com/anthropics/claude-code/issues/3217) - Verbose setting persistence
- [PR #580](https://github.com/anthropics/claude-code-action/pull/580) - Added `show_full_output`

## Success Criteria

1. Users can configure verbosity without using `claude_args`
2. Deprecated parameters log warnings but don't break workflows
3. Clear migration path documented for each deprecation
4. Verbosity levels are intuitive and well-documented
5. Backwards compatibility maintained until major version bump