@@ -1,6 +1,6 @@
 {
   "name": "prisma-cli",
-  "version": "8.0.0-rc.19",
+  "version": "8.0.0-rc.20",
   "private": true,
   "engines": {
     "node": ">=24"
 
@@ -1,7 +1,7 @@
 {
   "name": "@repo/cli-conformance",
   "private": true,
-  "version": "8.0.0-rc.19",
+  "version": "8.0.0-rc.20",
   "description": "Reusable conformance checks for the engine's consumers: import purity over built output, config-section validators that never throw, and verification of the tarballs a registry would receive. Depends on no package it checks.",
   "type": "module",
   "exports": {
@@ -24,7 +24,7 @@
     "test": "pnpm run typecheck && vitest run"
   },
   "devDependencies": {
-    "@repo/tsconfig": "workspace:8.0.0-rc.19",
+    "@repo/tsconfig": "workspace:8.0.0-rc.20",
     "@types/node": "^22.19.19",
     "es-module-lexer": "^2.1.0",
     "tsx": "^4.22.4",
 
@@ -59,8 +59,8 @@
   },
   "devDependencies": {
     "@prisma/management-api-sdk": "1.80.0",
-    "@repo/cli-conformance": "workspace:8.0.0-rc.19",
-    "@repo/tsconfig": "workspace:8.0.0-rc.19",
+    "@repo/cli-conformance": "workspace:8.0.0-rc.20",
+    "@repo/tsconfig": "workspace:8.0.0-rc.20",
     "@types/node": "^22.19.19",
     "ci-info": "^4.3.1",
     "tsdown": "^0.21.10",
 
@@ -1,7 +1,7 @@
 {
   "name": "@repo/cli-telemetry",
   "private": true,
-  "version": "8.0.0-rc.19",
+  "version": "8.0.0-rc.20",
   "description": "CLI telemetry child sender: the detached subprocess the engine hands a composed payload to, its system probes, and the POST",
   "type": "module",
   "sideEffects": [
@@ -35,7 +35,7 @@
     "@vercel/detect-agent": "^1.2.3"
   },
   "devDependencies": {
-    "@repo/tsconfig": "workspace:8.0.0-rc.19",
+    "@repo/tsconfig": "workspace:8.0.0-rc.20",
     "@types/node": "^22.19.19",
     "tsdown": "^0.21.10",
     "typescript": "^6.0.3",
 
@@ -1,6 +1,6 @@
 {
   "name": "@prisma/cli",
-  "version": "8.0.0-rc.19",
+  "version": "8.0.0-rc.20",
   "description": "Command-line interface for the Prisma Developer Platform.",
   "type": "module",
   "bin": {
@@ -50,7 +50,7 @@
   "dependencies": {
     "@manypkg/tools": "^2.1.2",
     "@prisma/cli-engine": "workspace:0.6.2",
-    "@prisma/composer-cli": "0.25.0",
+    "@prisma/composer-cli": "0.26.0",
     "@prisma/compute-sdk": "0.43.0",
     "@prisma/management-api-sdk": "1.80.0",
     "@prisma/orm-toolchain": "8.0.0-rc.14",
@@ -62,11 +62,11 @@
     "open": "^11.0.0"
   },
   "devDependencies": {
-    "@prisma/composer": "0.25.0",
+    "@prisma/composer": "0.26.0",
     "@prisma/credentials-store": "^7.8.0",
-    "@repo/cli-conformance": "workspace:8.0.0-rc.19",
-    "@repo/cli-telemetry": "workspace:8.0.0-rc.19",
-    "@repo/tsconfig": "workspace:8.0.0-rc.19",
+    "@repo/cli-conformance": "workspace:8.0.0-rc.20",
+    "@repo/cli-telemetry": "workspace:8.0.0-rc.20",
+    "@repo/tsconfig": "workspace:8.0.0-rc.20",
     "@types/node": "^22.19.19",
     "@types/cross-spawn": "^6.0.6",
     "tsdown": "^0.21.10",
 
@@ -110,14 +110,6 @@ async function tarball(): Promise<readonly Finding[]> {
       enginePackage: "@prisma/cli-engine",
       familyPackages: ["@prisma/composer-cli", "@prisma/orm-toolchain"],
       exceptions: [
-        {
-          familyPackage: "@prisma/composer-cli",
-          familyPin: "0.6.1",
-          shellPin: "0.6.2",
-          reason: "engine 0.6.2 must publish before composer-cli can peer it",
-          removeWhen:
-            "composer-cli releases peering 0.6.2 and the follow-up bump PR pins that release",
-        },
         {
           familyPackage: "@prisma/orm-toolchain",
           familyPin: "0.6.1",
 
@@ -34,12 +34,20 @@ const MISSING_PRISMA_CONFIG_PATH = join(
   "missing-prisma.config.ts",
 );
 
-/** A prisma.config.ts whose only section is composer's. */
-const COMPOSER_SECTION_CONFIG_PATH = join(
+/** A composer section that still carries the retired `configPath`. */
+const COMPOSER_CONFIG_PATH_CONFIG_PATH = join(
   dirname(fileURLToPath(import.meta.url)),
   "fixtures",
   "config",
-  "composer-section.config.ts",
+  "composer-config-path.config.ts",
+);
+
+/** A composer section built with `@prisma/composer/config`. */
+const COMPOSER_VALID_CONFIG_PATH = join(
+  dirname(fileURLToPath(import.meta.url)),
+  "fixtures",
+  "config",
+  "composer-valid.config.ts",
 );
 
 const SEMVER_PREFIX = /^\d+\.\d+\.\d+/;
@@ -492,7 +500,10 @@ describe("buildCli", () => {
    *  stdout is not a TTY here, so the stream is JSON, and JSON escapes
    *  every separator in a Windows path — no path the CLI printed is a
    *  substring of the stream that carried it. */
-  function resultError(stdoutText: string): Diagnostic {
+  function resultFailure(stdoutText: string): {
+    readonly error: Diagnostic;
+    readonly diagnostics: readonly Diagnostic[];
+  } {
     const frames = stdoutText
       .split("\n")
       .filter((line) => line !== "")
@@ -501,81 +512,74 @@ describe("buildCli", () => {
     if (last?.kind !== "result" || last.envelope.ok) {
       throw new Error(`expected a failed result frame, got: ${stdoutText}`);
     }
-    return last.envelope.error;
+    return {
+      error: last.envelope.error,
+      diagnostics: last.envelope.diagnostics,
+    };
   }
 
-  /** Composer's `dev` through the real bin, against the fixture whose
-   *  composer section names a config file that is not there. */
-  async function runComposerDev(): Promise<{
+  /** Composer's `dev` through the real bin, reading the given config. */
+  async function runComposerDev(configPath: string): Promise<{
     readonly exitCode: number;
     readonly error: Diagnostic;
+    readonly diagnostics: readonly Diagnostic[];
   }> {
     const proc = makeProcess({
-      argv: [
-        "node",
-        "bin.js",
-        "dev",
-        "--config",
-        COMPOSER_SECTION_CONFIG_PATH,
-        "src/service.ts",
-      ],
+      argv: ["node", "bin.js", "dev", "--config", configPath, "src/service.ts"],
     });
 
     const exitCode = await main(proc);
-    return { exitCode, error: resultError(proc.stdoutText) };
+    return { exitCode, ...resultFailure(proc.stdoutText) };
   }
 
   /**
    * The mount's config wiring, end to end: the section name composer's
-   * family declares, read by the bin's real disk loader, reaching
-   * composer's own handler as the path it acts on.
-   *
-   * Every platform but Windows. `dev` is the only composer command
-   * that reaches config discovery without credentials — `deploy` stops
-   * at the credential check — and it refuses Windows before it reads
-   * the section it was handed, so no shipped command can show the
-   * section arriving there. The test after this one pins what Windows
-   * can still show.
+   * family declares, read by the bin's real disk loader and checked by
+   * composer's own validator before any handler runs, so every
+   * platform sees the same refusal.
    */
-  it.skipIf(process.platform === "win32")(
-    "hands the composer section of prisma.config.ts to the composer family",
-    async () => {
-      const { exitCode, error } = await runComposerDev();
-
-      expect(exitCode).toBe(2);
-      expect(error.code).toBe("CONFIG.FILE_MISSING");
-      // Composer resolves the section's relative path against the
-      // prisma.config.ts that declared it, not against the cwd.
-      expect(error.where?.path).toBe(
-        join(
-          dirname(COMPOSER_SECTION_CONFIG_PATH),
-          "named-by-the-section.config.ts",
-        ),
-      );
-      expect(error.why).toContain("there is no walk to fall back on");
-    },
-  );
+  it("refuses a composer section that still names a config file", async () => {
+    const { exitCode, error, diagnostics } = await runComposerDev(
+      COMPOSER_CONFIG_PATH_CONFIG_PATH,
+    );
+
+    expect(exitCode).toBe(2);
+    expect(error).toMatchObject({
+      code: "CLI.CONFIG_SECTION_INVALID",
+      summary: `The 'composer' section of ${COMPOSER_CONFIG_PATH_CONFIG_PATH} is invalid.`,
+    });
+    expect(diagnostics).toEqual([
+      expect.objectContaining({
+        code: "CONFIG.FIELD_RETIRED",
+        severity: "error",
+        meta: { field: "configPath" },
+        where: { path: COMPOSER_CONFIG_PATH_CONFIG_PATH },
+      }),
+    ]);
+  });
 
   /**
-   * What Windows still shows: the bin evaluated the config file, the
-   * engine accepted its `composer` section, and the command reached
-   * composer's own operation — which then refuses the platform. A
-   * mis-wired section would fail here as a config diagnostic instead.
-   * What it does not show is the section's path reaching composer's
-   * config discovery, since the refusal comes first.
-   *
-   * When composer supports Windows this test fails, and the pair
-   * collapses back into the one above.
+   * `dev --help` never evaluates the config, so a valid section shows
+   * only on a run that validates it: composer's validator accepts the
+   * section and the handler runs. Its first step imports the entry the
+   * host passed, which does not exist; on Windows the handler refuses
+   * the platform before that.
    */
-  it.runIf(process.platform === "win32")(
-    "on Windows, composer's dev refuses the platform before it reads the section",
-    async () => {
-      const { exitCode, error } = await runComposerDev();
+  it("hands a valid composer section to composer's dev", async () => {
+    const { exitCode, error } = await runComposerDev(
+      COMPOSER_VALID_CONFIG_PATH,
+    );
 
-      expect(exitCode).toBe(2);
-      expect(error.code).toBe("DEV.PLATFORM_UNSUPPORTED");
-    },
-  );
+    expect(exitCode).toBe(2);
+    expect(error).toMatchObject(
+      process.platform === "win32"
+        ? { code: "DEV.PLATFORM_UNSUPPORTED" }
+        : {
+            code: "COMPOSE.ENTRY_UNLOADABLE",
+            summary: expect.stringContaining(join("src", "service.ts")),
+          },
+    );
+  });
 
   it("runs --version through the real tree, printing the version with exit 0", async () => {
     const proc = makeProcess({
 
@@ -4,6 +4,6 @@ import { definePrismaConfig } from "@prisma/cli-engine";
 // appearing in one of this repository's directories above these
 // fixtures can never join a test's chain.
 export default definePrismaConfig({
-  composer: { configPath: "./named-by-the-section.config.ts" },
+  composer: { configPath: "./prisma-composer.config.ts" },
   parent: false,
 });
@@ -0,0 +1,18 @@
+import { definePrismaConfig } from "@prisma/cli-engine";
+import { defineConfig as composer } from "@prisma/composer/config";
+import { nodeBuild } from "@prisma/composer/node/control";
+
+const build = nodeBuild();
+
+export default definePrismaConfig({
+  composer: composer({
+    extensions: [build],
+    state: {
+      extension: build.id,
+      create: () => {
+        throw new Error("no command in these tests reaches the state store");
+      },
+    },
+  }),
+  parent: false,
+});
@@ -42,7 +42,7 @@
     "test": "vitest run"
   },
   "devDependencies": {
-    "@repo/tsconfig": "workspace:8.0.0-rc.19",
+    "@repo/tsconfig": "workspace:8.0.0-rc.20",
     "@types/node": "^22.19.19",
     "tsdown": "^0.21.10",
     "typescript": "^6.0.3",
Original file line number	Diff line number	Diff line change
`@@ -1,6 +1,6 @@`
`1`	`1`	`{`
`2`	`2`	`"name": "prisma-cli",`
`3`		`- "version": "8.0.0-rc.19",`
	`3`	`+ "version": "8.0.0-rc.20",`
`4`	`4`	`"private": true,`
`5`	`5`	`"engines": {`
`6`	`6`	`"node": ">=24"`