Day-0 placeholder: stim+pymatching+fastapi+openenv-core, /healthz live

Dockerfile

@@ -0,0 +1,25 @@
+FROM python:3.11-slim
+
+ENV PYTHONUNBUFFERED=1 \
+    PIP_NO_CACHE_DIR=1 \
+    PIP_DISABLE_PIP_VERSION_CHECK=1
+
+RUN useradd -m -u 1000 user
+USER user
+ENV PATH="/home/user/.local/bin:$PATH"
+
+WORKDIR /app
+
+# Day-0 deployment-substrate dependencies (Section 11 of the plan):
+# stim + pymatching + fastapi + openenv-core, plus uvicorn for the server.
+RUN pip install --user --no-cache-dir \
+        "stim>=1.13,<2.0" \
+        "pymatching>=2.2,<3.0" \
+        "fastapi>=0.110" \
+        "uvicorn[standard]>=0.27" \
+        "openenv-core>=0.2.1"
+
+COPY --chown=user app.py /app/app.py
+
+EXPOSE 7860
+CMD ["python", "-m", "uvicorn", "app:app", "--host", "0.0.0.0", "--port", "7860"]

README.md

@@ -1,11 +1,49 @@
 ---
 title: QuantumScribe
-emoji: 👀
-colorFrom: purple
-colorTo: red
+emoji: 🩺
+colorFrom: indigo
+colorTo: pink
 sdk: docker
+app_port: 7860
 pinned: false
 license: mit
+short_description: Day-0 placeholder for the Qubit-Medic OpenEnv server.
+tags:
+  - openenv
+  - reinforcement-learning
+  - quantum-error-correction
+  - stim
+  - pymatching
 ---
 
-Check out the configuration reference at https://huggingface.co/docs/hub/spaces-config-reference
+# QuantumScribe — Day-0 placeholder
+
+This Space is the **deployment-substrate placeholder** for the
+**Qubit-Medic** OpenEnv server, an RL training environment that teaches
+an LLM to decode errors on the rotated surface code.
+
+## Try it
+
+* `GET /` — root metadata.
+* `GET /healthz` — liveness probe; returns `{"ok": true, "stim_version": "...", ...}`.
+
+```bash
+curl https://ronitraj-quantumscribe.hf.space/healthz
+```
+
+## What's coming
+
+This placeholder will be replaced by the real **Qubit-Medic** environment:
+
+| Endpoint | What it does |
+|---|---|
+| `POST /reset` | Sample a fresh syndrome + observation for the LLM. |
+| `POST /step`  | Score the LLM's predicted Pauli frame with five independent rewards (logical correction, syndrome consistency, Hamming overlap, format compliance, PyMatching beat-rate). |
+| `GET  /health` | Curriculum + episode statistics. |
+| `GET  /healthz` | Liveness (already live on this placeholder). |
+
+## Stack
+
+* [Stim](https://github.com/quantumlib/Stim) — Clifford circuit simulator.
+* [PyMatching](https://github.com/oscarhiggott/PyMatching) — minimum-weight matching baseline.
+* [FastAPI](https://fastapi.tiangolo.com/) + [openenv-core](https://pypi.org/project/openenv-core/) — server + RL contract.

app.py

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+"""QuantumScribe - Day-0 deployment-substrate placeholder.
+
+This minimal FastAPI app proves the Hugging Face Spaces deployment
+substrate works for the Qubit-Medic / QuantumScribe project:
+
+* Stim + PyMatching + FastAPI + openenv-core install cleanly in HF's
+  build environment (Day-0 step 2).
+* GET /healthz returns {"ok": true, "stim_version": "..."}, proving the
+  server boots and the heavy quantum dependency loads (Day-0 step 3).
+* The endpoint is reachable from a browser (Day-0 step 4) and from a
+  Colab `requests.get(...)` call (Day-0 step 5).
+
+Once all Day-0 gates pass, this file is replaced by the real Qubit-Medic
+OpenEnv server (qubit_medic.server.app) at the same Space URL, inheriting
+the warm build cache.
+"""
+from __future__ import annotations
+
+import sys
+
+import stim
+from fastapi import FastAPI
+
+
+app = FastAPI(
+    title="QuantumScribe (Qubit-Medic) - Hello Space",
+    description="Day-0 deployment-substrate placeholder for the Qubit-Medic "
+                "OpenEnv server. Will be replaced by the real env shortly.",
+    version="0.0.1-placeholder",
+)
+
+
+_PYMATCHING_VERSION: str
+try:
+    import pymatching as _pm
+    _PYMATCHING_VERSION = getattr(_pm, "__version__", "unknown")
+except Exception as exc:
+    _PYMATCHING_VERSION = f"import-error: {exc}"
+
+_OPENENV_VERSION: str
+try:
+    import openenv as _oe
+    _OPENENV_VERSION = getattr(_oe, "__version__", "unknown")
+except Exception as exc:
+    _OPENENV_VERSION = f"import-error: {exc}"
+
+
+@app.get("/")
+def root() -> dict:
+    return {
+        "service": "QuantumScribe (Qubit-Medic)",
+        "status": "Day-0 placeholder live",
+        "next": "POST /reset and /step will become available once the real "
+                "DecoderEnvironment is pushed.",
+        "endpoints": ["/", "/healthz"],
+        "links": {
+            "github": "https://github.com/ronitraj (replace with repo URL once public)",
+            "openenv_docs": "https://meta-pytorch.org/OpenEnv/",
+        },
+    }
+
+
+@app.get("/healthz")
+def healthz() -> dict:
+    """Day-0 liveness probe.
+
+    Returns the Stim version - so curl-ing this in a browser or from Colab
+    proves both that networking works AND that the heavy quantum deps
+    actually loaded. This is the literal endpoint the plan calls for.
+    """
+    return {
+        "ok": True,
+        "stim_version": stim.__version__,
+        "pymatching_version": _PYMATCHING_VERSION,
+        "openenv_version": _OPENENV_VERSION,
+        "python_version": sys.version.split()[0],
+        "service": "QuantumScribe",
+    }