diff --git a/src/lib/sandbox-base-image-platform-digest.test.ts b/src/lib/sandbox-base-image-platform-digest.test.ts
index 476ca15dfe4..f39ee9e2433 100644
--- a/src/lib/sandbox-base-image-platform-digest.test.ts
+++ b/src/lib/sandbox-base-image-platform-digest.test.ts
@@ -197,13 +197,24 @@ describe("sandbox base-image pinned platform digest resolution", () => {
     });
   });
 
-  it("falls back to the Dockerfile-pinned digest when RepoDigests JSON is malformed", () => {
+  it("preserves metadata for an exact digest when RepoDigests JSON is malformed (#9386)", () => {
     dockerMocks.imageInspect.mockImplementation((ref: string) => ({
       status: ref === REF ? 0 : 1,
     }));
     dockerMocks.imageInspectFormat.mockImplementation((format: string, ref: string) =>
       (
-        new Map([[`{{json .RepoDigests}}\0${REF}`, "{not-json"]]).get(`${format}\0${ref}`) ?? ""
+        new Map([
+          [`{{json .RepoDigests}}\0${REF}`, "{not-json"],
+          [
+            `{{json .}}\0${REF}`,
+            JSON.stringify({
+              Id: IMAGE_ID,
+              RepoDigests: [],
+              Os: "linux",
+              Architecture: "amd64",
+            }),
+          ],
+        ]).get(`${format}\0${ref}`) ?? ""
       ).trim(),
     );
 
@@ -218,6 +229,11 @@ describe("sandbox base-image pinned platform digest resolution", () => {
       digest: DIGEST,
       source: "pinned",
       pinnedRemoteRef: REF,
+      metadata: {
+        ref: REF,
+        digest: DIGEST,
+        imageId: IMAGE_ID,
+      },
     });
     expect(traceMocks.add).toHaveBeenCalledWith(
       "nemoclaw.sandbox_base_image.repodigest_parse_failed",
@@ -226,6 +242,49 @@ describe("sandbox base-image pinned platform digest resolution", () => {
     expect(dockerMocks.build).not.toHaveBeenCalled();
   });
 
+  it("preserves an exact override when Docker reports a different repository digest (#9386)", () => {
+    dockerMocks.imageInspect.mockImplementation((ref: string) => ({
+      status: ref === PLATFORM_REF ? 0 : 1,
+    }));
+    dockerMocks.imageInspectFormat.mockImplementation((format: string, ref: string) =>
+      (
+        new Map([
+          [`{{json .RepoDigests}}\0${PLATFORM_REF}`, JSON.stringify([REF])],
+          [
+            `{{json .}}\0${PLATFORM_REF}`,
+            JSON.stringify({
+              Id: IMAGE_ID,
+              RepoDigests: [REF],
+              Os: "linux",
+              Architecture: "amd64",
+            }),
+          ],
+        ]).get(`${format}\0${ref}`) ?? ""
+      ).trim(),
+    );
+
+    const resolved = resolveSandboxBaseImage({
+      ...resolutionOptions(),
+      envVar: "NEMOCLAW_SANDBOX_BASE_IMAGE_REF",
+      env: {
+        ...resolutionOptions().env,
+        NEMOCLAW_SANDBOX_BASE_IMAGE_REF: PLATFORM_REF,
+      },
+    });
+
+    expect(resolved).toMatchObject({
+      ref: PLATFORM_REF,
+      digest: PLATFORM_DIGEST,
+      source: "override",
+      metadata: {
+        ref: PLATFORM_REF,
+        digest: PLATFORM_DIGEST,
+        imageId: IMAGE_ID,
+      },
+    });
+    expect(dockerMocks.build).not.toHaveBeenCalled();
+  });
+
   it("rejects a pinned resolution hint from a stale Dockerfile pin", () => {
     const options = resolutionOptions();
     const stalePin = `${IMAGE_NAME}@sha256:${"c".repeat(64)}`;
diff --git a/src/lib/sandbox-base-image.ts b/src/lib/sandbox-base-image.ts
index d628490687c..d7be1c13d1d 100644
--- a/src/lib/sandbox-base-image.ts
+++ b/src/lib/sandbox-base-image.ts
@@ -116,6 +116,7 @@ function hasCurrentLocalBuildProvenance(
 function getRepoDigest(
   imageName: string,
   imageRef: string,
+  preserveExactDigestRef = false,
 ): { digest: string; ref: string } | null {
   const referencesExpectedRepository =
     imageRef === imageName ||
@@ -147,6 +148,7 @@ function getRepoDigest(
     });
     return pinnedDigest;
   }
+  if (preserveExactDigestRef && pinnedDigest) return pinnedDigest;
   const repoDigest = Array.isArray(repoDigests)
     ? repoDigests.find((entry) => String(entry).startsWith(`${imageName}@sha256:`))
     : null;
@@ -157,6 +159,7 @@ function getRepoDigest(
 
 type PulledCandidateOptions = {
   pinnedRemoteRef?: string;
+  preserveExactDigestRef?: boolean;
   refreshBeforeValidation?: boolean;
   refreshIfLocalInvalid?: boolean;
 };
@@ -299,7 +302,11 @@ function validatePulledCandidate(
     return null;
   }
 
-  const repoDigest = getRepoDigest(imageName, imageRef);
+  const repoDigest = getRepoDigest(
+    imageName,
+    imageRef,
+    candidateOptions.preserveExactDigestRef === true,
+  );
   return {
     ref: repoDigest?.ref || imageRef,
     digest: repoDigest?.digest || null,
@@ -485,6 +492,7 @@ export function resolveSandboxBaseImage(
       );
     }
     const resolved = resolvePulledCandidate(options.imageName, override, "override", options, {
+      preserveExactDigestRef: true,
       refreshBeforeValidation: true,
     });
     if (resolved?.digest) return finish(resolved);
diff --git a/src/lib/sandbox-base-image/resolution-metadata.test.ts b/src/lib/sandbox-base-image/resolution-metadata.test.ts
index 6f30f83192c..68b4831c77e 100644
--- a/src/lib/sandbox-base-image/resolution-metadata.test.ts
+++ b/src/lib/sandbox-base-image/resolution-metadata.test.ts
@@ -108,6 +108,33 @@ describe("sandbox base-image resolution metadata lifecycle", () => {
     );
   });
 
+  it("preserves an exact digest resolution when Docker omits RepoDigests (#9386)", () => {
+    mocks.dockerImageInspectFormat.mockReturnValue(
+      JSON.stringify({
+        Id: inspected.Id,
+        Os: inspected.Os,
+        Architecture: inspected.Architecture,
+      }),
+    );
+
+    expect(createSandboxBaseImageResolutionMetadata(options, KEY, publishedResolution)).toEqual(
+      metadata,
+    );
+  });
+
+  it("rejects sparse RepoDigests when the resolved reference is not the exact digest", () => {
+    mocks.dockerImageInspectFormat.mockReturnValue(
+      JSON.stringify({ ...inspected, RepoDigests: [] }),
+    );
+
+    expect(
+      createSandboxBaseImageResolutionMetadata(options, KEY, {
+        ...publishedResolution,
+        ref: `${IMAGE_NAME}:published`,
+      }),
+    ).toBeNull();
+  });
+
   it("finalizes a local fallback with identity metadata and no repository digest (#4680)", () => {
     const localResolution: SandboxBaseImageResolution = {
       ref: options.localTag,
diff --git a/src/lib/sandbox-base-image/resolution-metadata.ts b/src/lib/sandbox-base-image/resolution-metadata.ts
index 7f8a48bb5ee..bfbd0ec39e8 100644
--- a/src/lib/sandbox-base-image/resolution-metadata.ts
+++ b/src/lib/sandbox-base-image/resolution-metadata.ts
@@ -25,6 +25,14 @@ export function inspectLocalImageMetadata(imageRef: string): LocalImageMetadata
   }
 }
 
+function isExactSameRepositoryDigestRef(
+  imageName: string,
+  digest: string,
+  ref: string,
+): boolean {
+  return /^sha256:[0-9a-f]{64}$/u.test(digest) && ref === `${imageName}@${digest}`;
+}
+
 export function validateSandboxBaseImageResolutionMetadata(input: {
   metadata: SandboxBaseImageResolutionMetadata;
   expectedKey: string;
@@ -67,7 +75,10 @@ export function validateSandboxBaseImageResolutionMetadata(input: {
   if (metadata.digest) {
     const expectedRepoDigest = `${input.imageName}@${metadata.digest}`;
     const repoDigests = Array.isArray(inspected.RepoDigests) ? inspected.RepoDigests : [];
-    if (!repoDigests.some((entry) => String(entry) === expectedRepoDigest)) {
+    if (
+      !isExactSameRepositoryDigestRef(input.imageName, metadata.digest, metadata.ref) &&
+      !repoDigests.some((entry) => String(entry) === expectedRepoDigest)
+    ) {
       return { ok: false, reason: "repo_digest_missing" };
     }
   }
@@ -89,7 +100,19 @@ export function createSandboxBaseImageResolutionMetadata(
   if (resolution.digest) {
     const expectedRepoDigest = `${options.imageName}@${resolution.digest}`;
     const repoDigests = Array.isArray(inspected?.RepoDigests) ? inspected.RepoDigests : [];
-    if (!repoDigests.some((entry) => String(entry) === expectedRepoDigest)) return null;
+    // Docker may omit RepoDigests after resolving an exact platform manifest.
+    // The resolver's exact same-repository digest ref remains immutable proof.
+    const exactResolvedReference = isExactSameRepositoryDigestRef(
+      options.imageName,
+      resolution.digest,
+      resolution.ref,
+    );
+    if (
+      !exactResolvedReference &&
+      !repoDigests.some((entry) => String(entry) === expectedRepoDigest)
+    ) {
+      return null;
+    }
   }
 
   return {
@@ -115,7 +138,11 @@ export function finalizeSandboxBaseImageResolution(
   resolution: SandboxBaseImageResolution,
 ): SandboxBaseImageResolution {
   let locallyProvenResolution = resolution;
-  if (resolution.digest) {
+  const preserveExactOverride =
+    resolution.source === "override" &&
+    resolution.digest !== null &&
+    isExactSameRepositoryDigestRef(options.imageName, resolution.digest, resolution.ref);
+  if (resolution.digest && !preserveExactOverride) {
     const inspected = inspectLocalImageMetadata(resolution.ref);
     const expectedRepoDigest = `${options.imageName}@${resolution.digest}`;
     const matchingRepoDigests = Array.isArray(inspected?.RepoDigests)
diff --git a/src/lib/sandbox-base-image/resolution-validation.test.ts b/src/lib/sandbox-base-image/resolution-validation.test.ts
index 40cfc4104fa..1b974833a1b 100644
--- a/src/lib/sandbox-base-image/resolution-validation.test.ts
+++ b/src/lib/sandbox-base-image/resolution-validation.test.ts
@@ -58,6 +58,22 @@ describe("sandbox base-image resolution validation", () => {
     });
   });
 
+  it("validates an exact digest reference when Docker reports another repository digest (#9386)", () => {
+    const digest = `sha256:${"a".repeat(64)}`;
+    const exactMetadata = {
+      ...metadata,
+      ref: `${metadata.imageName}@${digest}`,
+      digest,
+    };
+
+    expect(
+      validate(exactMetadata, {
+        ...inspected,
+        RepoDigests: [`${metadata.imageName}@sha256:${"b".repeat(64)}`],
+      }),
+    ).toEqual({ ok: true });
+  });
+
   it("validates local fallback images by identity without RepoDigests (#4680)", () => {
     expect(
       validate(