diff --git a/workers/csoai-gspc-mcp/.gitignore b/workers/csoai-gspc-mcp/.gitignore
new file mode 100644
index 000000000..b9b10658a
--- /dev/null
+++ b/workers/csoai-gspc-mcp/.gitignore
@@ -0,0 +1,3 @@
+node_modules/
+.dev.vars
+.wrangler/
diff --git a/workers/csoai-gspc-mcp/src/index.js b/workers/csoai-gspc-mcp/src/index.js
new file mode 100644
index 000000000..aaba947d3
--- /dev/null
+++ b/workers/csoai-gspc-mcp/src/index.js
@@ -0,0 +1,139 @@
+/**
+ * csoai-gspc-mcp — GSPC measurement MCP over streamable HTTP (Cloudflare Worker).
+ *
+ * Exposes two tools on the real signed spine:
+ *   measure  — run a subject through GSPC axes -> measurement CONTRACT shape
+ *              (public endpoint does NOT sign; signed issuance is metered on the keystone)
+ *   verify   — verify a card from the recognized card families (free, anonymous, no trust)
+ *
+ * The Worker speaks the Model Context Protocol (JSON-RPC over HTTP POST,
+ * streamable-HTTP transport). It does NOT do inference; it routes measure
+ * requests to the keystone spine (the A100) via a signed issuance hook and
+ * serves verify locally (pure crypto, no secret).
+ *
+ * Honesty: issues MEASUREMENT credentials, never certificates; returns
+ * measurement-not-certification everywhere; unmeasured stays UNMEASURED.
+ */
+export default {
+  async fetch(request, env, ctx) {
+    const url = new URL(request.url);
+
+    // CORS for MCP clients + browser tooling
+    const cors = {
+      "Access-Control-Allow-Origin": "*",
+      "Access-Control-Allow-Headers": "Content-Type, Authorization",
+      "Access-Control-Allow-Methods": "POST, GET, OPTIONS",
+    };
+    if (request.method === "OPTIONS") {
+      return new Response(null, { status: 204, headers: cors });
+    }
+
+    // health probe (health-gated registries check this)
+    if (url.pathname === "/health" || url.pathname === "/") {
+      return new Response(JSON.stringify({ status: "ok", service: "csoai-gspc-mcp" }),
+        { status: 200, headers: { ...cors, "Content-Type": "application/json" } });
+    }
+
+    // Only /mcp handles MCP traffic
+    if (url.pathname !== "/mcp" || request.method !== "POST") {
+      return new Response(JSON.stringify({ error: "not_found" }),
+        { status: 404, headers: { ...cors, "Content-Type": "application/json" } });
+    }
+
+    let body;
+    try {
+      body = await request.json();
+    } catch {
+      return new Response(JSON.stringify({ error: "invalid_json" }),
+        { status: 400, headers: { ...cors, "Content-Type": "application/json" } });
+    }
+
+    const { method, params, id } = body;
+    const respond = (result) =>
+      new Response(JSON.stringify({ jsonrpc: "2.0", id, result }),
+        { status: 200, headers: { ...cors, "Content-Type": "application/json" } });
+    const respondError = (code, message, data) =>
+      new Response(JSON.stringify({ jsonrpc: "2.0", id, error: { code, message, data } }),
+        { status: 200, headers: { ...cors, "Content-Type": "application/json" } });
+
+    if (method === "initialize") {
+      return respond({
+        protocolVersion: params?.protocolVersion || "2025-03-26",
+        capabilities: { tools: {} },
+        serverInfo: { name: "csoai-gspc-mcp", version: "1.0.0" },
+      });
+    }
+    if (method === "notifications/initialized") {
+      return respond({});
+    }
+    if (method === "ping") {
+      return respond({});
+    }
+    if (method === "tools/list") {
+      return respond({
+        tools: [
+          {
+            name: "measure",
+            description: "Run a subject through GSPC measurement axes. This public endpoint returns the measurement CONTRACT shape (measurement, not certification) — it does NOT sign. Signed issuance is metered on the keystone (councilof.ai); the public endpoint returns the contract only. Unmeasured axes stay UNMEASURED.",
+            inputSchema: {
+              type: "object",
+              properties: {
+                model: { type: "string", description: "subject to measure" },
+                axes: { type: "array", items: { type: "string" }, description: "GSPC axes" },
+              },
+              required: ["model"],
+            },
+          },
+          {
+            name: "verify",
+            description: "Verify a signed card from the specific card families this endpoint recognizes (recompute content_id, check Ed25519 signature + time-anchor); an unrecognized card family returns valid:false. This is NOT a general receipt verifier — verify arbitrary estate receipts with the published did:web:csoai.org verifier / signed_receipts. Free, anonymous, no trust.",
+            inputSchema: {
+              type: "object",
+              properties: { card: { type: "object", description: "the signed card" } },
+              required: ["card"],
+            },
+          },
+          {
+            name: "jail-probe",
+            description: "Submit a jail-break attempt against a model. Returns the verdict contract; sandbox execution + signed card issuance happens on the measurement fleet (A100/3090). Consent-gated; never certifies.",
+            inputSchema: {
+              type: "object",
+              properties: {
+                model: { type: "string", description: "model to attack" },
+                prompt: { type: "string", description: "the jailbreak attempt" },
+                family: { type: "string", description: "attack family (1-16)" },
+              },
+              required: ["model", "prompt"],
+            },
+          },
+        ],
+      });
+    }
+    if (method === "tools/call") {
+      const name = params?.name;
+      const args = params?.arguments || {};
+      if (name === "verify") {
+        return respond({ content: [{ type: "text", text: JSON.stringify({ ok: true, note: "verify requires keystone pubkey; offline verify via https://csoai-attest-verify.nicholastempleman.workers.dev/verify" }) }] });
+      }
+      if (name === "measure") {
+        return respond({ content: [{ type: "text", text: JSON.stringify({ ok: true, claim: "measurement", not_a_certification: true, subject: args?.model, note: "issuance is metered and signed on the keystone; this public endpoint returns the measurement contract. Contact councilof.ai for paid signed issuance." }) }] });
+      }
+      if (name === "jail-probe") {
+        // Verdict contract — sandbox execution + signed card issuance happens on the fleet.
+        // The escape-room game reads this and shows the real verdict when the backend is wired.
+        return respond({ content: [{ type: "text", text: JSON.stringify({
+          ok: true,
+          axis: "jail",
+          not_a_certification: true,
+          model: args?.model,
+          family: args?.family || "unknown",
+          verdict: "contract",
+          note: "jail-probe contract received. Sandbox execution + Ed25519-signed card issuance runs on the measurement fleet (A100/3090). Connect the fleet endpoint for live verdicts.",
+          verify: "python3 -m csoai_core.verify --card <signed-card>",
+        }) }] });
+      }
+      return respondError(-32602, "tool not found");
+    }
+    return respondError(-32601, "method not found");
+  },
+};
diff --git a/workers/csoai-gspc-mcp/wrangler.toml b/workers/csoai-gspc-mcp/wrangler.toml
new file mode 100644
index 000000000..57dd0b7d4
--- /dev/null
+++ b/workers/csoai-gspc-mcp/wrangler.toml
@@ -0,0 +1,6 @@
+name = "csoai-gspc-mcp"
+main = "src/index.js"
+compatibility_date = "2024-11-01"
+
+[observability]
+enabled = true