Initial commit: prompt template manager

React + Tailwind frontend, FastAPI backend, settings.json storage.
Supports preset CRUD, live variable filling, and AI rewrite via OpenAI.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/main.py

@@ -0,0 +1,120 @@
+import os
+from pathlib import Path
+
+from fastapi import FastAPI, HTTPException
+from fastapi.responses import FileResponse
+from fastapi.staticfiles import StaticFiles
+from openai import AsyncOpenAI
+from pydantic import BaseModel
+
+import backend.storage as storage
+from backend.models import extract_vars
+
+DIST = Path(__file__).parent.parent / "frontend" / "dist"
+OPENAI_MODEL = os.getenv("OPENAI_MODEL", "gpt-4.1")
+
+app = FastAPI()
+
+
+# ── Models ────────────────────────────────────────────────────────────────────
+
+class PresetBody(BaseModel):
+    name: str
+    description: str = ""
+    template: str
+
+
+class SettingsBody(BaseModel):
+    openai_api_key: str
+
+
+class RewriteBody(BaseModel):
+    prompt: str
+
+
+# ── Presets ───────────────────────────────────────────────────────────────────
+
+@app.get("/api/presets")
+def get_presets():
+    return {"presets": storage.list_presets()}
+
+
+@app.post("/api/presets", status_code=201)
+def create_preset(body: PresetBody):
+    variables = extract_vars(body.template)
+    return storage.create_preset(body.name, body.description, body.template, variables)
+
+
+@app.put("/api/presets/{preset_id}")
+def update_preset(preset_id: str, body: PresetBody):
+    variables = extract_vars(body.template)
+    result = storage.update_preset(preset_id, {
+        "name": body.name,
+        "description": body.description,
+        "template": body.template,
+        "variables": variables,
+    })
+    if result is None:
+        raise HTTPException(status_code=404, detail="Preset not found")
+    return result
+
+
+@app.delete("/api/presets/{preset_id}")
+def delete_preset(preset_id: str):
+    if not storage.delete_preset(preset_id):
+        raise HTTPException(status_code=404, detail="Preset not found")
+    return {"ok": True}
+
+
+# ── Settings ──────────────────────────────────────────────────────────────────
+
+@app.get("/api/settings")
+def get_settings():
+    key = storage.get_openai_key()
+    return {"openai_api_key_set": bool(key)}
+
+
+@app.post("/api/settings")
+def update_settings(body: SettingsBody):
+    storage.set_openai_key(body.openai_api_key)
+    return {"ok": True}
+
+
+# ── AI Rewrite ────────────────────────────────────────────────────────────────
+
+@app.post("/api/rewrite")
+async def rewrite_prompt(body: RewriteBody):
+    key = storage.get_openai_key()
+    if not key:
+        raise HTTPException(status_code=400, detail="OpenAI API key not configured")
+
+    client = AsyncOpenAI(api_key=key)
+    try:
+        response = await client.chat.completions.create(
+            model=OPENAI_MODEL,
+            messages=[
+                {
+                    "role": "system",
+                    "content": (
+                        "You are a prompt engineer. Rewrite the user's prompt to be clearer, "
+                        "more specific, and more effective for an AI assistant. "
+                        "Return only the rewritten prompt, no explanation."
+                    ),
+                },
+                {"role": "user", "content": body.prompt},
+            ],
+        )
+    except Exception as e:
+        raise HTTPException(status_code=502, detail=str(e))
+
+    return {"rewritten": response.choices[0].message.content}
+
+
+# ── SPA static serving (must be last) ────────────────────────────────────────
+
+if DIST.exists():
+    app.mount("/assets", StaticFiles(directory=DIST / "assets"), name="assets")
+
+    @app.get("/{full_path:path}")
+    def serve_spa(full_path: str):
+        return FileResponse(DIST / "index.html")

backend/models.py

@@ -0,0 +1,13 @@
+import re
+
+VAR_RE = re.compile(r'\{\{([a-zA-Z_][a-zA-Z0-9_]*)\}\}')
+
+
+def extract_vars(template: str) -> list[str]:
+    seen = set()
+    result = []
+    for m in VAR_RE.finditer(template):
+        if m.group(1) not in seen:
+            seen.add(m.group(1))
+            result.append(m.group(1))
+    return result

backend/storage.py

@@ -0,0 +1,73 @@
+import json
+import secrets
+from datetime import datetime, timezone
+from pathlib import Path
+
+SETTINGS_PATH = Path(__file__).parent.parent / "settings.json"
+
+
+def _now():
+    return datetime.now(timezone.utc).isoformat().replace("+00:00", "Z")
+
+
+def _read():
+    if not SETTINGS_PATH.exists():
+        return {"openai_api_key": "", "presets": []}
+    return json.loads(SETTINGS_PATH.read_text(encoding="utf-8"))
+
+
+def _write(data):
+    tmp = SETTINGS_PATH.with_suffix(".tmp")
+    tmp.write_text(json.dumps(data, indent=2), encoding="utf-8")
+    tmp.replace(SETTINGS_PATH)
+
+
+def list_presets():
+    return _read()["presets"]
+
+
+def create_preset(name, description, template, variables):
+    data = _read()
+    preset = {
+        "id": secrets.token_hex(4),
+        "name": name,
+        "description": description,
+        "template": template,
+        "variables": variables,
+        "created_at": _now(),
+        "updated_at": _now(),
+    }
+    data["presets"].append(preset)
+    _write(data)
+    return preset
+
+
+def update_preset(preset_id, fields):
+    data = _read()
+    for p in data["presets"]:
+        if p["id"] == preset_id:
+            p.update(fields)
+            p["updated_at"] = _now()
+            _write(data)
+            return p
+    return None
+
+
+def delete_preset(preset_id):
+    data = _read()
+    before = len(data["presets"])
+    data["presets"] = [p for p in data["presets"] if p["id"] != preset_id]
+    if len(data["presets"]) == before:
+        return False
+    _write(data)
+    return True
+
+
+def get_openai_key():
+    return _read().get("openai_api_key", "")
+
+
+def set_openai_key(key: str):
+    data = _read()
+    data["openai_api_key"] = key
+    _write(data)