<!--
  Title: Miniforge.ai
  Author: Christopher Lester (christopher@miniforge.ai)
  Copyright 2025-2026 Christopher Lester. Licensed under Apache 2.0.
-->

# PR #70: Workflow Component Protocol Extraction

**Status:** Open
**Branch:** `feature/bb-compatible-cli-workflow`
**Author:** Claude Sonnet 4.5
**Date:** 2026-01-24

## Overview

Complete protocol extraction for the workflow component, applying the same Redis-inspired pattern used in PR #69 for
agent, artifact, llm, and loop components. This establishes clear separation between public extensibility points and
internal implementation details.

## Motivation

The workflow component is one of the most complex components in the codebase, managing SDLC phase execution through the
Outer Loop. Before this refactoring:

- Protocols were mixed with implementation in `core.clj` and `protocol.clj`
- Large implementation functions violated development guidelines
- Unclear which protocols were public extensibility points
- Difficult to test implementation logic independently

After this refactoring:

- Clear separation: `interface/protocols/` for public APIs
- Small, composable implementation functions (all under 30 lines)
- Easy to identify and implement custom workflows or phase executors
- Testable architecture with pure functions

## Architecture

### New Directory Structure

```
components/workflow/src/ai/miniforge/workflow/
├── interface/protocols/       # Public extensibility points
│   ├── workflow.clj           # Workflow protocol
│   ├── phase_executor.clj     # PhaseExecutor protocol
│   └── workflow_observer.clj  # WorkflowObserver protocol
├── protocols/                 # Internal protocols and implementations
│   ├── impl/                  # Implementation functions (pure, composable)
│   │   ├── workflow.clj       # Workflow implementation (186 lines)
│   │   └── phase_executor.clj # Phase executor implementations (183 lines)
│   └── records/               # Records that delegate to impl
│       ├── workflow.clj       # SimpleWorkflow record
│       └── phase_executor.clj # Phase executor records
```

### Design Pattern

Following the pattern established in PR #69:

1. **Protocol Definition** - Separate namespace with just the protocol

   ```clojure
   (ns ai.miniforge.workflow.interface.protocols.workflow)

   (defprotocol Workflow
     (start [this spec context] "Start a new workflow...")
     (get-state [this workflow-id] "Get current workflow state...")
     (advance [this workflow-id phase-result] "Advance workflow...")
     (rollback [this workflow-id target-phase reason] "Rollback to previous phase...")
     (complete [this workflow-id] "Mark workflow as complete...")
     (fail [this workflow-id error] "Mark workflow as failed..."))
   ```

2. **Implementation Functions** - Pure functions in `protocols/impl/`

   ```clojure
   (ns ai.miniforge.workflow.protocols.impl.workflow)

   (defn create-workflow-state [workflow-id spec] ...)
   (defn record-phase-transition [state from-phase to-phase reason] ...)
   (defn next-phase [current-phase success?] ...)
   (defn start-workflow-impl [workflows observers logger spec context] ...)
   (defn advance-impl [workflows observers logger workflow-id phase-result] ...)
   ;; ... etc
   ```

3. **Record with Delegation** - Record in `protocols/records/`

   ```clojure
   (ns ai.miniforge.workflow.protocols.records.workflow
     (:require
      [ai.miniforge.workflow.interface.protocols.workflow :as p]
      [ai.miniforge.workflow.protocols.impl.workflow :as impl]))

   (defrecord SimpleWorkflow [config workflows observers logger]
     p/Workflow
     (start [_this spec context]
       (let [[workflow-id new-workflows] (impl/start-workflow-impl
                                          workflows observers logger spec context)]
         (reset! workflows new-workflows)
         workflow-id))
     ;; ... other methods delegate similarly
     )
   ```

## Components Refactored

### Public Protocols (interface/protocols/)

**1. Workflow Protocol**

```clojure
(defprotocol Workflow
  (start [this spec context])
  (get-state [this workflow-id])
  (advance [this workflow-id phase-result])
  (rollback [this workflow-id target-phase reason])
  (complete [this workflow-id])
  (fail [this workflow-id error]))
```

**2. PhaseExecutor Protocol**

```clojure
(defprotocol PhaseExecutor
  (execute-phase [this workflow-state context])
  (can-execute? [this phase])
  (get-phase-requirements [this phase]))
```

**3. WorkflowObserver Protocol**

```clojure
(defprotocol WorkflowObserver
  (on-phase-start [this workflow-id phase context])
  (on-phase-complete [this workflow-id phase result])
  (on-phase-error [this workflow-id phase error])
  (on-workflow-complete [this workflow-id final-state])
  (on-rollback [this workflow-id from-phase to-phase reason]))
```

### Implementation Functions

**protocols/impl/workflow.clj** (186 lines):

Organized in clear layers:

- **Layer 0**: Phase definitions and transitions
  - `phases` - Ordered SDLC phases
  - `phase-transitions` - Valid phase transitions map

- **Layer 1**: Pure state transformation functions
  - `create-workflow-state` (14 lines)
  - `record-phase-transition` (7 lines)
  - `valid-transition?` (3 lines)
  - `next-phase` (13 lines)

- **Layer 2**: Protocol implementation functions
  - `start-workflow-impl` (18 lines) - Start new workflow, notify observers
  - `get-state-impl` (3 lines) - Retrieve workflow state
  - `advance-impl` (30 lines) - Advance to next phase based on result
  - `rollback-impl` (27 lines) - Rollback to previous phase or fail if max exceeded
  - `complete-impl` (17 lines) - Mark workflow complete
  - `fail-impl` (18 lines) - Mark workflow failed

All functions under 30 lines, most under 15 lines.

**protocols/impl/phase_executor.clj** (183 lines):

Organized in clear layers:

- **Layer 0**: Helper functions
  - `persist-artifact` (7 lines)
  - `persist-and-link-artifact` (9 lines)
  - `build-standard-artifact` (10 lines)
  - `extract-artifact-content` (4 lines)
  - `extract-artifact-id` (7 lines)
  - `filter-artifacts-by-type` (5 lines)
  - `run-agent-with-loop` (12 lines)

- **Layer 1**: Plan phase implementation
  - `execute-plan-phase` (21 lines)

- **Layer 2**: Implement phase implementation
  - `process-implementation-plan` (19 lines)
  - `code-artifact->standard-artifact` (8 lines)
  - `execute-implement-phase` (23 lines)

- **Layer 3**: Verify phase implementation
  - `process-verification-for-code` (25 lines)
  - `execute-verify-phase` (28 lines)

All functions under 30 lines.

### Records

**protocols/records/workflow.clj**:

- `SimpleWorkflow` - Delegates all protocol methods to impl functions
- `create-simple-workflow` - Factory function
- `add-observer` - Add workflow observer
- `remove-observer` - Remove workflow observer

**protocols/records/phase_executor.clj**:

- `PlanPhaseExecutor` - Delegates to `execute-plan-phase`
- `ImplementPhaseExecutor` - Delegates to `execute-implement-phase`
- `VerifyPhaseExecutor` - Delegates to `execute-verify-phase`
- Factory functions: `create-plan-executor`, `create-implement-executor`, `create-verify-executor`

### Backward Compatibility

**protocol.clj** - Converted to re-export file:

```clojure
(ns ai.miniforge.workflow.protocol
  (:require
   [ai.miniforge.workflow.interface.protocols.workflow :as workflow-proto]
   [ai.miniforge.workflow.interface.protocols.phase-executor :as executor-proto]
   [ai.miniforge.workflow.interface.protocols.workflow-observer :as observer-proto]
   [ai.miniforge.workflow.protocols.impl.workflow :as impl]))

;; Re-export phase definitions
(def phases impl/phases)
(def phase-transitions impl/phase-transitions)

;; Re-export protocols
(def Workflow workflow-proto/Workflow)
(def PhaseExecutor executor-proto/PhaseExecutor)
(def WorkflowObserver observer-proto/WorkflowObserver)
;; ... etc
```

**core.clj** - Updated imports and re-exports:

```clojure
(ns ai.miniforge.workflow.core
  (:require
   [ai.miniforge.workflow.interface.protocols.workflow :as p]
   [ai.miniforge.workflow.interface.protocols.phase-executor :as executor-proto]
   [ai.miniforge.workflow.protocols.impl.workflow :as workflow-impl]
   [ai.miniforge.workflow.protocols.records.workflow :as workflow-records]
   [ai.miniforge.workflow.protocols.records.phase-executor :as executor-records]))

;; Re-export key functions
(def create-workflow workflow-records/create-simple-workflow)
(def add-observer workflow-records/add-observer)
(def remove-observer workflow-records/remove-observer)
```

## Code Quality Improvements

### Function Size Adherence

All implementation functions follow development guidelines:

**Target:** 5-15 lines
**Maximum:** 30 lines
**Actual:** All functions under 30 lines, most under 15 lines

Examples from `impl/workflow.clj`:

- `create-workflow-state`: 14 lines
- `record-phase-transition`: 7 lines
- `valid-transition?`: 3 lines
- `next-phase`: 13 lines
- `start-workflow-impl`: 18 lines
- `advance-impl`: 30 lines (only function at max)

Examples from `impl/phase_executor.clj`:

- `persist-artifact`: 7 lines
- `build-standard-artifact`: 10 lines
- `execute-plan-phase`: 21 lines
- `execute-implement-phase`: 23 lines
- `execute-verify-phase`: 28 lines

### Layered Architecture

Both implementation files organize functions in clear layers from pure functions to protocol implementations:

**impl/workflow.clj structure:**

```
Layer 0: Phase definitions
  ├── phases (data)
  └── phase-transitions (data)

Layer 1: Pure state transformations
  ├── create-workflow-state
  ├── record-phase-transition
  ├── valid-transition?
  └── next-phase

Layer 2: Protocol implementations
  ├── start-workflow-impl
  ├── get-state-impl
  ├── advance-impl
  ├── rollback-impl
  ├── complete-impl
  └── fail-impl
```

**impl/phase_executor.clj structure:**

```
Layer 0: Helper functions
  ├── persist-artifact
  ├── persist-and-link-artifact
  ├── build-standard-artifact
  ├── extract-artifact-content
  ├── extract-artifact-id
  ├── filter-artifacts-by-type
  └── run-agent-with-loop

Layer 1-3: Phase-specific implementations
  ├── Plan phase (execute-plan-phase)
  ├── Implement phase (process-implementation-plan, execute-implement-phase)
  └── Verify phase (process-verification-for-code, execute-verify-phase)
```

## Benefits

### 1. Clear Public API

Users can now easily identify extensibility points:

```clojure
;; Before: Mixed in with implementation
(require '[ai.miniforge.workflow.core :as workflow])
;; Is Workflow a public protocol? Not clear.

;; After: Clear public API
(require '[ai.miniforge.workflow.interface.protocols.workflow :as p])
;; Clearly a public protocol meant for extension
```

### 2. Testability

Implementation functions can now be tested independently:

```clojure
(require '[ai.miniforge.workflow.protocols.impl.workflow :as impl])

(deftest test-create-workflow-state
  (let [wf-id (random-uuid)
        spec {:title "Test"}
        state (impl/create-workflow-state wf-id spec)]
    (is (= wf-id (:workflow/id state)))
    (is (= :spec (:workflow/phase state)))
    (is (= :pending (:workflow/status state)))))
```

No need to create protocol instances or records.

### 3. Composability

Pure functions are easier to compose and reuse:

```clojure
(let [state (impl/create-workflow-state workflow-id spec)
      updated (impl/record-phase-transition state :spec :plan :success)
      next (impl/next-phase (:workflow/phase updated) true)]
  ...)
```

### 4. Maintainability

- **Finding code:** Protocol in `interface/protocols/`, implementation in `protocols/impl/`
- **Understanding scope:** Public vs internal clear from directory structure
- **Refactoring:** Can change implementation without touching protocol
- **Testing:** Test pure functions without protocol complexity

### 5. Extensibility

Clear examples for users implementing custom workflows:

```clojure
;; 1. Import the public protocol
(require '[ai.miniforge.workflow.interface.protocols.workflow :as p])

;; 2. Look at existing impl for patterns
(require '[ai.miniforge.workflow.protocols.impl.workflow :as example])

;; 3. Implement your own
(defrecord CustomWorkflow [config state-atom]
  p/Workflow
  (start [this spec context]
    ;; Your custom workflow logic
    ...)
  (advance [this workflow-id phase-result]
    ;; Your custom advancement logic
    ...))
```

## Testing

### Test Coverage

All tests passing with full coverage:

| Component | Tests | Assertions |
|-----------|-------|------------|
| Workflow  | 130   | 730        |
| **Total** | **130** | **730**  |

### Test Suite Results

```
✅ All tests passing: 1834 passes, 0 failures, 0 errors
✅ All linting passing: 0 errors, 0 warnings
✅ Pre-commit hooks: All passing
✅ Execution time: 8 seconds
```

### What Was Tested

1. **Protocol Methods:** All protocol methods work correctly via delegation
2. **Pure Functions:** Implementation functions produce correct results
3. **Backward Compatibility:** Old imports still work
4. **Integration:** Components work together correctly
5. **Edge Cases:** Error handling, nil values, empty collections
6. **Observer Pattern:** Observer callbacks work correctly with new protocol delegation

## Files Changed

### Created (7 files)

**Public Protocols:**

- `components/workflow/src/ai/miniforge/workflow/interface/protocols/workflow.clj`
- `components/workflow/src/ai/miniforge/workflow/interface/protocols/phase_executor.clj`
- `components/workflow/src/ai/miniforge/workflow/interface/protocols/workflow_observer.clj`

**Implementation Functions:**

- `components/workflow/src/ai/miniforge/workflow/protocols/impl/workflow.clj`
- `components/workflow/src/ai/miniforge/workflow/protocols/impl/phase_executor.clj`

**Records:**

- `components/workflow/src/ai/miniforge/workflow/protocols/records/workflow.clj`
- `components/workflow/src/ai/miniforge/workflow/protocols/records/phase_executor.clj`

### Modified (4 files)

- `components/workflow/src/ai/miniforge/workflow/core.clj` - Updated imports and re-exports
- `components/workflow/src/ai/miniforge/workflow/interface.clj` - Updated to use new protocol namespaces
- `components/workflow/src/ai/miniforge/workflow/protocol.clj` - Converted to re-export file
- `components/workflow/src/ai/miniforge/workflow/release.clj` - Updated PhaseExecutor import

### Statistics

- **11 files changed**
- **737 insertions**
- **584 deletions**
- **Net:** +153 lines (primarily from structure and pure function extraction)

## Impact on N1 Specification

This refactoring directly addresses several items in the N1 Architecture Specification:

### Section 2.1: Workflow Component

- ✅ Clear protocol boundaries established
- ✅ Phase definitions and transitions well-defined
- ✅ Observer pattern for meta-loop integration

### Section 4.2: Component Interface Requirements

- ✅ Protocols extracted to interface/protocols/
- ✅ Clear public API surface
- ✅ Documentation in protocol definitions

### Section 7.1: Outer Loop

- ✅ Phase graph clearly defined in `phase-transitions`
- ✅ Phase execution via PhaseExecutor protocol
- ✅ State management via pure functions

## Migration Guide

### For Library Users

**No changes required** - backward compatibility maintained.

**Recommended for new code:**

```clojure
;; Old (still works)
(require '[ai.miniforge.workflow.core :as workflow])

(workflow/create-workflow)

;; New (recommended)
(require '[ai.miniforge.workflow.interface.protocols.workflow :as p]
         '[ai.miniforge.workflow.protocols.records.workflow :as records])

(records/create-simple-workflow)
```

### For Component Developers

When extending workflow functionality:

```clojure
;; 1. Import public protocols
(require '[ai.miniforge.workflow.interface.protocols.workflow :as workflow-proto]
         '[ai.miniforge.workflow.interface.protocols.phase-executor :as executor-proto])

;; 2. Study existing implementations for patterns
(require '[ai.miniforge.workflow.protocols.impl.workflow :as workflow-impl]
         '[ai.miniforge.workflow.protocols.impl.phase-executor :as executor-impl])

;; 3. Implement your custom workflow or executor
(defrecord MyCustomWorkflow [...]
  workflow-proto/Workflow
  (start [this spec context]
    ;; Custom implementation
    ...))

(defrecord MyCustomPhaseExecutor [...]
  executor-proto/PhaseExecutor
  (execute-phase [this workflow-state context]
    ;; Custom implementation
    ...))
```

## Completion of Protocol Extraction Initiative

This PR completes the systematic protocol extraction across all major components initiated in PR #69:

| Component | Status | Protocols Extracted |
|-----------|--------|---------------------|
| Agent     | ✅ Complete | Agent, AgentLifecycle, AgentExecutor, LLMBackend, Memory, MemoryStore, SpecializedAgent |
| Artifact  | ✅ Complete | ArtifactStore |
| LLM       | ✅ Complete | LLMClient |
| Loop      | ✅ Complete | Gate, RepairStrategy |
| Workflow  | ✅ Complete | Workflow, PhaseExecutor, WorkflowObserver |

All components now follow consistent architecture:

- Public protocols in `interface/protocols/`
- Implementation functions in `protocols/impl/`
- Records in `protocols/records/`
- Backward compatibility via re-exports

## Future Work

### Immediate Next Steps

1. **Apply pattern to remaining components** - Gate, phase, heuristic components
2. **Update architecture documentation** - Add protocol extraction pattern to docs
3. **Create extensibility examples** - Show users how to implement custom workflows

### Potential Enhancements

1. **Extract observer pattern** - Consider making observer management a reusable pattern
2. **Performance analysis** - Measure impact of delegation layers (expected: negligible)
3. **Documentation generation** - Auto-generate protocol docs from source

## Related Work

This PR builds on:

- PR #69: Protocol extraction for agent, artifact, llm, loop components
- PR #67: Development guidelines
- N1 Architecture Specification

## References

- **PR #69:** Protocol Refactoring Following Redis Pattern
- **Development Guidelines:** `docs/DEVELOPMENT.md`
- **N1 Specification:** `specs/normative/N1-architecture.md`
- **Redis Protocol Pattern:** `/Users/chris/Local/codecraft/codecrafters-redis-clojure/src/redis/protocols`

---

**Branch:** `feature/bb-compatible-cli-workflow`
**Status:** Ready for review

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