feat: sft router — /export and /stats endpoints

app/sft.py

@@ -9,12 +9,15 @@ set_sft_config_dir() in test fixtures.
 """
 from __future__ import annotations
 
+import json
 import logging
+from datetime import datetime, timezone
 from pathlib import Path
 from typing import Literal
 
 import yaml
 from fastapi import APIRouter, HTTPException
+from fastapi.responses import StreamingResponse
 from pydantic import BaseModel
 
 from app.utils import append_jsonl, read_jsonl, write_jsonl
@@ -203,3 +206,68 @@ def post_undo(req: UndoRequest):
         write_jsonl(_approved_file(), [r for r in approved if r.get("id") != req.id])
 
     return {"ok": True}
+
+
+# ── GET /export ─────────────────────────────────────────────────────────────
+
+@router.get("/export")
+def get_export():
+    """Stream approved records as SFT-ready JSONL for download."""
+    approved = read_jsonl(_approved_file())
+    exportable = [
+        r for r in approved
+        if r.get("status") == "approved"
+        and r.get("corrected_response")
+        and str(r["corrected_response"]).strip()
+    ]
+
+    def generate():
+        for r in exportable:
+            record = {
+                "messages": r.get("prompt_messages", []) + [
+                    {"role": "assistant", "content": r["corrected_response"]}
+                ]
+            }
+            yield json.dumps(record) + "\n"
+
+    timestamp = datetime.now(timezone.utc).strftime("%Y%m%d-%H%M%S")
+    return StreamingResponse(
+        generate(),
+        media_type="application/x-ndjson",
+        headers={
+            "Content-Disposition": f'attachment; filename="sft_export_{timestamp}.jsonl"'
+        },
+    )
+
+
+# ── GET /stats ──────────────────────────────────────────────────────────────
+
+@router.get("/stats")
+def get_stats():
+    """Return counts by status, model, and task type."""
+    records = _read_candidates()
+    by_status: dict[str, int] = {}
+    by_model: dict[str, int] = {}
+    by_task_type: dict[str, int] = {}
+
+    for r in records:
+        status = r.get("status", "unknown")
+        by_status[status] = by_status.get(status, 0) + 1
+        model = r.get("model_name", "unknown")
+        by_model[model] = by_model.get(model, 0) + 1
+        task_type = r.get("task_type", "unknown")
+        by_task_type[task_type] = by_task_type.get(task_type, 0) + 1
+
+    approved = read_jsonl(_approved_file())
+    export_ready = sum(
+        1 for r in approved
+        if r.get("corrected_response") and str(r["corrected_response"]).strip()
+    )
+
+    return {
+        "total": len(records),
+        "by_status": by_status,
+        "by_model": by_model,
+        "by_task_type": by_task_type,
+        "export_ready": export_ready,
+    }

tests/test_sft.py

@@ -260,3 +260,83 @@ def test_undo_already_needs_review_returns_409(client, tmp_path):
     _populate_candidates(tmp_path, [_make_record("a")])
     r = client.post("/api/sft/undo", json={"id": "a"})
     assert r.status_code == 409
+
+
+# ── /api/sft/export ──────────────────────────────────────────────────────────
+
+def test_export_returns_approved_as_sft_jsonl(client, tmp_path):
+    from app import sft as sft_module
+    from app.utils import write_jsonl
+    approved = {
+        **_make_record("a"),
+        "status": "approved",
+        "corrected_response": "def add(a, b): return a + b",
+        "prompt_messages": [
+            {"role": "system", "content": "You are a coding assistant."},
+            {"role": "user", "content": "Write a Python add function."},
+        ],
+    }
+    write_jsonl(sft_module._approved_file(), [approved])
+    _populate_candidates(tmp_path, [approved])
+
+    r = client.get("/api/sft/export")
+    assert r.status_code == 200
+    assert "application/x-ndjson" in r.headers["content-type"]
+    lines = [l for l in r.text.splitlines() if l.strip()]
+    assert len(lines) == 1
+    record = json.loads(lines[0])
+    assert record["messages"][-1] == {
+        "role": "assistant", "content": "def add(a, b): return a + b"
+    }
+    assert record["messages"][0]["role"] == "system"
+    assert record["messages"][1]["role"] == "user"
+
+
+def test_export_excludes_non_approved(client, tmp_path):
+    from app import sft as sft_module
+    from app.utils import write_jsonl
+    records = [
+        {**_make_record("a"), "status": "discarded", "corrected_response": None},
+        {**_make_record("b"), "status": "needs_review", "corrected_response": None},
+    ]
+    write_jsonl(sft_module._approved_file(), records)
+    r = client.get("/api/sft/export")
+    assert r.text.strip() == ""
+
+
+def test_export_empty_when_no_approved_file(client):
+    r = client.get("/api/sft/export")
+    assert r.status_code == 200
+    assert r.text.strip() == ""
+
+
+# ── /api/sft/stats ───────────────────────────────────────────────────────────
+
+def test_stats_counts_by_status(client, tmp_path):
+    from app import sft as sft_module
+    from app.utils import write_jsonl
+    records = [
+        _make_record("a"),
+        {**_make_record("b"), "status": "approved", "corrected_response": "ok"},
+        {**_make_record("c"), "status": "discarded"},
+        {**_make_record("d"), "status": "model_rejected"},
+    ]
+    _populate_candidates(tmp_path, records)
+    write_jsonl(sft_module._approved_file(), [records[1]])
+    r = client.get("/api/sft/stats")
+    assert r.status_code == 200
+    data = r.json()
+    assert data["total"] == 4
+    assert data["by_status"]["needs_review"] == 1
+    assert data["by_status"]["approved"] == 1
+    assert data["by_status"]["discarded"] == 1
+    assert data["by_status"]["model_rejected"] == 1
+    assert data["export_ready"] == 1
+
+
+def test_stats_empty_when_no_data(client):
+    r = client.get("/api/sft/stats")
+    assert r.status_code == 200
+    data = r.json()
+    assert data["total"] == 0
+    assert data["export_ready"] == 0