# Phase 01.8: Detect and Validate Technology Stack [MANDATORY]

**Invoke tech-stack-detector subagent to detect technologies and validate against tech-stack.md:**

```
Task(
  subagent_type="tech-stack-detector",
  description="Detect and validate tech stack",
  prompt="Analyze the project structure in the current directory.

  Detect:
  1. Primary programming language
  2. Framework/runtime
  3. Test framework
  4. Build tool
  5. Package manager

  Then validate against devforgeai/specs/context/tech-stack.md if it exists.

  Return JSON with detected technologies, validation results, and recommended commands.

  CRITICAL: If conflicts found between detected and specified technologies, provide clear resolution options."
)
```

**Parse subagent JSON response:**

```javascript
result = parse_json(subagent_output)

# Extract detected technologies
LANGUAGE = result["detected"]["language"]["primary"]
FRAMEWORK = result["detected"]["framework"]["name"]
TEST_FRAMEWORK = result["detected"]["test_framework"]["primary"]

# Extract workflow commands (CRITICAL - used in subsequent phases)
TEST_COMMAND = result["commands"]["test"]
TEST_COVERAGE_COMMAND = result["commands"]["test_coverage"]
BUILD_COMMAND = result["commands"]["build"]
INSTALL_COMMAND = result["commands"]["install"]

# Check validation status
VALIDATION_STATUS = result["validation"]["status"]

IF VALIDATION_STATUS == "PASS":
    Display: "✓ Technology stack validated"
    Display: "  - Language: {LANGUAGE}"
    Display: "  - Framework: {FRAMEWORK}"
    Display: "  - Test framework: {TEST_FRAMEWORK}"
    Display: "  - Test command: {TEST_COMMAND}"

ELIF VALIDATION_STATUS == "FAIL":
    # CRITICAL conflicts detected - HALT
    Display: "❌ Technology stack validation FAILED"
    Display: "Conflicts detected between project and tech-stack.md"

    FOR conflict in result["validation"]["conflicts"]:
        IF conflict["severity"] == "CRITICAL":
            # Use AskUserQuestion to resolve
            AskUserQuestion:
                question: "Project uses {conflict['detected']} but tech-stack.md specifies {conflict['specified']}. How to resolve?"
                header: "Tech Conflict"
                options:
                    - label: "Follow spec (update project)"
                      description: "Change project to use {conflict['specified']}"
                    - label: "Update spec (create ADR)"
                      description: "Update tech-stack.md, document in ADR"
                multiSelect: false

            # Handle user response
            IF "Update spec" chosen:
                # Create ADR, update tech-stack.md, re-validate

ELIF VALIDATION_STATUS == "ERROR":
    IF result["validation"]["context_missing"]:
        # tech-stack.md not found - invoke architecture skill
        Display: "❌ tech-stack.md not found"
        Display: "Invoking spec-driven-system-architecture skill..."
        Skill(command="spec-driven-system-architecture")

        # After architecture completes, re-run tech-stack-detector

# Store commands for Phases 1-5
$TEST_COMMAND = TEST_COMMAND
$TEST_COVERAGE_COMMAND = TEST_COVERAGE_COMMAND
$BUILD_COMMAND = BUILD_COMMAND
```

**Token cost:** ~700 tokens in skill context (~8,000 in isolated subagent context)
