fix: harden runtime config snapshot publication

backend/src/tht/tht-runner.ts

@@ -306,6 +306,12 @@ export class ThtRunner {
     return new Promise((resolve) => {
       const env: NodeJS.ProcessEnv = { ...process.env };
       delete env.THT_DATA_ROOT;
+      // Handoff variables are backend-owned capabilities, never inherited from an
+      // operator shell or forwarded request environment.
+      delete env.THT_RUNTIME_CONFIG_MANIFEST_SHA256;
+      delete env.THT_CONFIG_FD;
+      delete env.THT_CONFIG_MANIFEST_FD;
+      delete env.THT_CONFIG_MANIFEST_SHA256;
       clearPrincipalEnvironment(env);
       if (this.cfg.dataRoot !== undefined) env.THT_DATA_ROOT = this.cfg.dataRoot;
       if (this.principal) Object.assign(env, principalEnvironment(this.principal));
@@ -321,41 +327,27 @@ export class ThtRunner {
         env.THT_SSL_CA = ca;
       }
       let snapshotFd: number | undefined;
-      let canonicalFd: number | undefined;
-      let manifestFd: number | undefined;
       let ch;
       try {
         snapshotFd = workspaceConfigPath && this.runtimeSnapshots.has(workspaceConfigPath)
           ? this.openTrustedRuntimeSnapshot(workspaceConfigPath) : undefined;
         const lease = workspaceConfigPath ? this.runtimeLeases.get(workspaceConfigPath) : undefined;
-        // Registry leases retain the verified config bytes in fd 3 and the separately
-        // published manifest in fd 4. The argv remains the canonical -c pathname for
-        // diagnostics/compatibility; the harness never trusts that pathname for bytes.
-        canonicalFd = snapshotFd === undefined && lease
-          ? openSync(lease.path, fsConstants.O_RDONLY | fsConstants.O_NOFOLLOW) : undefined;
-        manifestFd = lease
-          ? openSync(lease.manifestPath, fsConstants.O_RDONLY | fsConstants.O_NOFOLLOW) : undefined;
-        if (lease) {
-          env.THT_CONFIG_FD = "3";
-          env.THT_CONFIG_MANIFEST_FD = "4";
-          env.THT_CONFIG_MANIFEST_SHA256 = lease.manifestSha256;
-        }
-        const handoffFd = snapshotFd ?? canonicalFd;
+        // Runtime leases use the canonical path plus an authenticated manifest digest.
+        // FD 3/4 remain reserved for the maintenance writer/root ABI.
+        if (lease) env.THT_RUNTIME_CONFIG_MANIFEST_SHA256 = lease.manifestSha256;
         ch = spawn(
           this.cfg.thtBin,
           snapshotFd === undefined ? this.buildArgv(args, workspaceConfigPath) : [...args, "-c", "/dev/fd/3"],
           {
             cwd: this.cfg.harnessDir,
             env,
-            ...(handoffFd === undefined ? {} : {
-              stdio: ["ignore", "pipe", "pipe", handoffFd, ...(manifestFd === undefined ? [] : [manifestFd])],
+            ...(snapshotFd === undefined ? {} : {
+              stdio: ["ignore", "pipe", "pipe", snapshotFd],
             }),
           },
         );
       } finally {
         if (snapshotFd !== undefined) closeSync(snapshotFd);
-        if (canonicalFd !== undefined) closeSync(canonicalFd);
-        if (manifestFd !== undefined) closeSync(manifestFd);
       }
       let stdout = "";
       let stderr = "";

backend/src/workspaces/runtime-config-lease.ts

@@ -14,7 +14,7 @@ import {
   type RuntimePaths,
   type SemanticRuntimeConfig,
 } from "./runtime-renderer.js";
-import { parseWorkspaceYaml, validateOperationalWorkspace, type WorkspaceDescriptor } from "./schema.js";
+import { parseWorkspaceYaml, serializeWorkspaceYaml, validateOperationalWorkspace, type WorkspaceDescriptor } from "./schema.js";
 
 export interface RuntimeConfigLease {
   path: string;
@@ -50,6 +50,8 @@ interface SnapshotIdentity {
   revisionContentRoot: string;
   digest: string;
   descriptorBlob?: string;
+  descriptorDev: string;
+  descriptorIno: string;
 }
 interface PublishedIdentity {
   path: string;
@@ -154,6 +156,8 @@ export class WorkspaceRuntimeConfigLeaseFactory {
       workspace_id: snapshot.workspaceId, workspace_revision: snapshot.workspaceRevision,
       descriptor_git_blob: snapshot.descriptorBlob!,
       descriptor_sha256: snapshot.digest,
+      descriptor_dev: snapshot.descriptorDev,
+      descriptor_ino: snapshot.descriptorIno,
       config_sha256: renderedDigest,
       config_dwh_binding: this.computeBinding(rendered),
     };
@@ -168,10 +172,14 @@ export class WorkspaceRuntimeConfigLeaseFactory {
 
   private helper(action: string, extra: Record<string, unknown>): any {
     const python = join(this.input.harnessDir, ".venv", "bin", "python");
-    const executable = existsSync(python) ? python : (process.env.PYTHON ?? "python3");
     const modulePath = existsSync(join(this.input.harnessDir, "tht", "runtime_config_lease_io.py"))
       ? join(this.input.harnessDir, "tht", "runtime_config_lease_io.py")
       : join(process.cwd(), "../harness/tht/runtime_config_lease_io.py");
+    // Fixtures may provide a temporary harness directory; still execute the real
+    // project helper environment, never a fabricated TypeScript binding.
+    const projectPython = join(dirname(dirname(modulePath)), ".venv", "bin", "python");
+    const executable = existsSync(python) ? python
+      : existsSync(projectPython) ? projectPython : (process.env.PYTHON ?? "python3");
     const helperArgs = existsSync(modulePath) ? [modulePath] : ["-m", "tht.runtime_config_lease_io"];
     const result = spawnSync(executable, helperArgs, { cwd: this.input.harnessDir,
       input: JSON.stringify({ action, ...extra }), encoding: "utf8",
@@ -188,12 +196,10 @@ export class WorkspaceRuntimeConfigLeaseFactory {
     try {
       const value = this.helper("binding", { config_hex: Buffer.from(content).toString("hex") });
       if (value && typeof value.workspace_id === "string" && typeof value.config_fingerprint === "string" && typeof value.input_fingerprint === "string") return value;
+      throw new Error("runtime config binding helper returned malformed output");
     } catch (error) {
-      // Development fixtures may intentionally omit the harness virtualenv. Production
-      // deployments always execute the real helper through harness/.venv/bin/python.
-      if (existsSync(join(this.input.harnessDir, ".venv", "bin", "python"))) throw error;
+      throw error instanceof Error ? error : new Error("runtime config binding failed");
     }
-    return { workspace_id: "unknown", config_fingerprint: `sha256:${digest(content)}`, input_fingerprint: `sha256:${digest(content)}` };
   }
 
   private publishSecure(workspaceId: string, revision: string, content: string, manifestBase: Record<string, unknown>): {path:string; manifestPath:string; manifest:string; manifest_sha256:string} {
@@ -231,11 +237,25 @@ export class WorkspaceRuntimeConfigLeaseFactory {
       snapshots_root: root, repository_root: repositoryRoot,
       workspace_revision: match[1], workspace_id: match[2],
     });
-    if (!verified || typeof verified.source !== "string"
-      || verified.sha256 !== digest(verified.source) || verified.snapshot_path !== path) {
+    if (!verified || typeof verified.source !== "string" || typeof verified.git_source !== "string"
+      || verified.sha256 !== digest(verified.source) || verified.snapshot_path !== path
+      || !/^\d+$/.test(String(verified.descriptor_dev)) || !/^\d+$/.test(String(verified.descriptor_ino))) {
       throw new Error("workspace snapshot integrity check failed");
     }
-    const workspace = validateOperationalWorkspace(parseWorkspaceYaml(verified.source));
+    // The registry's production canonicalizer is the sole descriptor equivalence
+    // rule. Raw token containment is not identity: it permits changed values.
+    let workspace: WorkspaceDescriptor;
+    let gitWorkspace: WorkspaceDescriptor;
+    try {
+      workspace = validateOperationalWorkspace(parseWorkspaceYaml(verified.source));
+      gitWorkspace = validateOperationalWorkspace(parseWorkspaceYaml(verified.git_source));
+      if (serializeWorkspaceYaml(workspace) !== serializeWorkspaceYaml(gitWorkspace)
+          || serializeWorkspaceYaml(workspace) !== verified.source) {
+        throw new Error("canonical descriptor differs from Git");
+      }
+    } catch (error) {
+      throw new Error(`workspace snapshot integrity check failed: ${error instanceof Error ? error.message : "invalid descriptor"}`);
+    }
     if (workspace.workspace.id !== match[2] || typeof verified.descriptor_git_blob !== "string") {
       throw new Error("workspace snapshot integrity check failed");
     }
@@ -243,6 +263,7 @@ export class WorkspaceRuntimeConfigLeaseFactory {
       workspace, workspaceId: match[2], workspaceRevision: match[1],
       revisionContentRoot: join(root, match[1]), digest: verified.sha256,
       descriptorBlob: verified.descriptor_git_blob,
+      descriptorDev: String(verified.descriptor_dev), descriptorIno: String(verified.descriptor_ino),
     };
   }
 }

backend/test/workspace-runtime-config-lease.test.ts

@@ -1,10 +1,11 @@
 import { test, expect } from "vitest";
 import { chmodSync, existsSync, lstatSync, mkdirSync, mkdtempSync, readFileSync, rmSync, writeFileSync } from "node:fs";
 import { tmpdir } from "node:os";
-import { join } from "node:path";
+import { dirname, join } from "node:path";
 import { execFileSync } from "node:child_process";
 import { createHash } from "node:crypto";
 import { WorkspaceRuntimeConfigLeaseFactory } from "../src/workspaces/runtime-config-lease.js";
+import { parseWorkspaceYaml, serializeWorkspaceYaml } from "../src/workspaces/schema.js";
 
 const workspace = "abc";
 const descriptor = `workspace:
@@ -33,13 +34,14 @@ llm_policy:
 
 function fixture() {
   const root = mkdtempSync(join(tmpdir(), "runtime-config-lease-"));
+  const canonicalDescriptor = serializeWorkspaceYaml(parseWorkspaceYaml(descriptor));
   const snapshots = join(root, "snapshots");
   const repo = join(root, "repo");
   mkdirSync(join(repo, "workspaces"), { recursive: true });
   execFileSync("git", ["init", "--initial-branch=main"], { cwd: repo });
   execFileSync("git", ["config", "user.name", "Fixture"], { cwd: repo });
   execFileSync("git", ["config", "user.email", "fixture@example.invalid"], { cwd: repo });
-  writeFileSync(join(repo, "workspaces", `${workspace}.yaml`), descriptor);
+  writeFileSync(join(repo, "workspaces", `${workspace}.yaml`), canonicalDescriptor);
   execFileSync("git", ["add", "."], { cwd: repo });
   execFileSync("git", ["commit", "-m", "fixture"], { cwd: repo });
   const actualCommit = execFileSync("git", ["rev-parse", "HEAD"], { cwd: repo, encoding: "utf8" }).trim();
@@ -50,17 +52,22 @@ function fixture() {
   const harness = join(root, "harness");
   mkdirSync(snapshotsDir, { recursive: true, mode: 0o700 });
   chmodSync(snapshots, 0o700);
+  const publicFiles = {
+    [`${workspace}.yaml`]: canonicalDescriptor,
+    [`${workspace}.env.example`]: "# fixture\n",
+    [`${workspace}.md`]: "# Lease\n",
+  };
+  for (const [name, contents] of Object.entries(publicFiles)) writeFileSync(join(snapshotsDir, name), contents, { mode: 0o400 });
   writeFileSync(join(snapshotsDir, "snapshot.json"), JSON.stringify({
     head: actualCommit,
     revisions: [{ id: workspace, commit: actualCommit, blob, snapshotPath }],
-    files: { [`${workspace}.yaml`]: createHash("sha256").update(descriptor).digest("hex") },
+    files: Object.fromEntries(Object.entries(publicFiles).map(([name, contents]) => [name, createHash("sha256").update(contents).digest("hex")])),
   }), { mode: 0o400 });
   mkdirSync(harness);
-  writeFileSync(snapshotPath, descriptor, { mode: 0o400 });
   const secret = join(root, "password");
   writeFileSync(secret, "secret", { mode: 0o600 });
   const configPath = join(harness, "config.yaml");
-  writeFileSync(configPath, "profile: test\n");
+  writeFileSync(configPath, "profile: workstation\n");
   const factory = new WorkspaceRuntimeConfigLeaseFactory({
     dataRoot, runtimeSnapshotRoot: snapshots, harnessDir: harness, configPath,
     env: {
@@ -72,7 +79,7 @@ function fixture() {
       internalEmbeddingModel: "qwen3-embedding:0.6b", internalEmbeddingDimensions: 1024,
     },
   });
-  return { root, snapshotPath, factory };
+  return { root, snapshotPath, factory, canonicalDescriptor };
 }
 
 test("session and maintenance share deterministic bytes and path", () => {
@@ -84,6 +91,9 @@ test("session and maintenance share deterministic bytes and path", () => {
     expect(readFileSync(session.path, "utf8")).toBe(readFileSync(maintenance.path, "utf8"));
     expect(lstatSync(session.path).mode & 0o777).toBe(0o400);
     expect(existsSync(maintenance.manifestPath)).toBe(true);
+    const manifest = JSON.parse(readFileSync(maintenance.manifestPath, "utf8"));
+    expect(manifest).toMatchObject({ version: 1, descriptor_dev: expect.any(String), descriptor_ino: expect.any(String) });
+    expect(existsSync(join(dirname(dirname(maintenance.path)), "runtime-config.lock"))).toBe(false);
     session.release(); maintenance.release();
     expect(existsSync(session.path)).toBe(true);
   } finally { rmSync(f.root, { recursive: true, force: true }); }
@@ -100,3 +110,34 @@ test("same revision changed bytes are refused", () => {
     first.release();
   } finally { rmSync(f.root, { recursive: true, force: true }); }
 });
+
+test("snapshot descriptor must equal the Git canonical descriptor", () => {
+  const f = fixture();
+  try {
+    const mutated = f.canonicalDescriptor.replace("database: analytics", "database: evil").replace("name: Lease", "name: Lease analytics");
+    chmodSync(f.snapshotPath, 0o600);
+    writeFileSync(f.snapshotPath, mutated, { mode: 0o600 });
+    chmodSync(f.snapshotPath, 0o400);
+    const manifestPath = join(dirname(f.snapshotPath), "snapshot.json");
+    const manifest = JSON.parse(readFileSync(manifestPath, "utf8"));
+    manifest.files[`${workspace}.yaml`] = createHash("sha256").update(mutated).digest("hex");
+    chmodSync(manifestPath, 0o600);
+    writeFileSync(manifestPath, JSON.stringify(manifest), { mode: 0o600 });
+    chmodSync(manifestPath, 0o400);
+    expect(() => f.factory.acquireSession(f.snapshotPath)).toThrow(/Git descriptor|integrity|identity/i);
+  } finally { rmSync(f.root, { recursive: true, force: true }); }
+});
+
+test("same-byte replacement of the registry descriptor is refused", () => {
+  const f = fixture();
+  try {
+    const first = f.factory.acquireSession(f.snapshotPath);
+    const replacement = `${f.snapshotPath}.replacement`;
+    writeFileSync(replacement, readFileSync(f.snapshotPath), { mode: 0o400 });
+    chmodSync(f.snapshotPath, 0o600);
+    rmSync(f.snapshotPath);
+    writeFileSync(f.snapshotPath, readFileSync(replacement), { mode: 0o400 });
+    expect(() => f.factory.acquireSession(f.snapshotPath)).toThrow(/identity|changed|mismatch|trusted/i);
+    first.release();
+  } finally { rmSync(f.root, { recursive: true, force: true }); }
+});