feat: add FlowRAG workflow memory & retrieval module with ChromaDB ba…

.gitignore

@@ -54,3 +54,10 @@ manpages/
 completions/crush.*sh
 .prettierignore
 .task
+
+# Local developer config (may contain API keys)
+/crush.json.bak
+/crush.local.json
+
+# FlowRAG local storage
+/flowrag_workflows.json

internal/flowrag/README.md

@@ -0,0 +1,132 @@
+# FlowRAG — Intelligent Workflow Memory & Retrieval
+
+FlowRAG is a **workflow learning and replay module** for Crush, the terminal AI coding assistant. It captures successful coding workflows, stores them in a ChromaDB vector database, and retrieves the best past experience via semantic search for future similar tasks.
+
+## How It Works
+
+### Trigger Detection (Dual Layer)
+
+**Primary: Skill-driven (AI semantic understanding)**
+
+FlowRAG is registered as a [Skill](../../skills/builtin/flowrag/SKILL.md) in Crush. The LLM automatically identifies when to trigger it:
+
+- A multi-step task completed with no errors
+- User expresses satisfaction or confirms the result
+- User explicitly asks to save/remember the workflow
+
+**Secondary: Keyword matching**
+
+The [CompletionDetector](detector.go) recognizes explicit markers:
+
+| Category | Examples |
+|----------|----------|
+| Colloquial confirmation | "ok", "好的", "done", "搞定了" |
+| Business markers | "task complete", "save workflow", "remember this" |
+
+### Data Flow
+
+```
+Task completed (Skill detection / keyword match)
+  → Prompt: "Save this workflow? (y/n)"
+    → Yes: Segmenter extracts successful steps (skips errors/retries)
+      → Embedding (OpenAI-compatible API / Trigram Hash)
+        → Store in ChromaDB / JSON File
+          → Next similar task: retrieve Top-K via semantic search
+            → Inject into system prompt for faster execution
+```
+
+## Architecture
+
+```
+internal/flowrag/
+├── detector.go          # Completion marker detection (Skill + keyword)
+├── segmenter.go         # Workflow segmentation (filter error steps)
+├── store.go             # Vector store (ChromaDB / JSON File backends)
+├── retriever.go         # Semantic search + context builder
+├── workflow.go          # Orchestrator (unified API)
+├── workflow_test.go     # 17 test cases
+├── cmd/
+│   ├── demo/            # Interactive CLI demo (zero-dependency)
+│   └── e2e_test/        # End-to-end semantic search verification
+└── README.md
+```
+
+## Tech Stack
+
+| Component | Backend | Notes |
+|-----------|---------|-------|
+| **Vector Store** | ChromaDB (default) | REST API v2, auto-creates `crush_workflows` collection |
+| **Fallback Store** | JSON File | Zero-dependency, used when ChromaDB is unavailable |
+| **Embedding** | OpenAI-compatible API | `text-embedding-3-small` or similar |
+| **Embedding (zero-dep)** | Trigram Hash | Deterministic, content-aware, no API needed |
+| **Similarity** | Cosine similarity (ChromaDB built-in) | — |
+| **Segmentation** | IsError field filtering | Precisely excludes failed/rollback steps |
+
+## Quick Start
+
+### Option A: ChromaDB (Recommended)
+
+```bash
+# Start ChromaDB
+docker run -d -p 8000:8000 chromadb/chroma
+```
+
+```go
+mgr, _ := flowrag.NewWorkflowManager(flowrag.Config{
+    ChromaDBURL:      "http://localhost:8000",
+    EmbeddingBaseURL: "https://api.openai.com/v1",
+    EmbeddingAPIKey:  "sk-xxx",
+    EmbeddingModel:   "text-embedding-3-small",
+})
+```
+
+### Option B: JSON File (Zero External Dependencies)
+
+```go
+mgr, _ := flowrag.NewWorkflowManager(flowrag.Config{
+    StorePath: "~/.crush/flowrag/workflows.json",
+})
+// ChromaDBURL left empty → falls back to file backend
+```
+
+### API Usage
+
+```go
+// Check if this message should trigger FlowRAG
+if mgr.Detector().ShouldTriggerFlowRAG(userMessage) {
+    // Confirm with user...
+}
+
+// Save successful workflow
+mgr.SaveSuccessfulWorkflow(ctx, SaveWorkflowInput{
+    UserPrompt: "Write an HTTP server",
+    Messages:   sessionMessages,
+    SessionID:  "session-123",
+})
+
+// Retrieve similar past workflows
+ctx := mgr.SearchAndBuildContext(ctx, "Create a REST API", 3)
+// Inject ctx into system prompt
+```
+
+## Interactive Demo
+
+```bash
+go run ./internal/flowrag/cmd/demo/
+```
+
+Run the demo, type `demo` to load 6 sample workflows spanning auth fixes, REST APIs, Python scripting, DB migrations, OAuth, and Docker Compose — then search with natural language queries and see semantic retrieval in action.
+
+## E2E Verification
+
+```bash
+go run ./internal/flowrag/cmd/e2e_test/
+```
+
+## Tests
+
+```bash
+go test ./internal/flowrag/... -v -count=1
+```
+
+17 test cases covering: detector (colloquial + business keywords), segmenter (success/error flow extraction), JSONFileStore (insert/search/empty), cosine similarity precision, retriever context building, and end-to-end integration.