diff --git a/crates/socket-patch-core/src/patch/vendor/cargo.rs b/crates/socket-patch-core/src/patch/vendor/cargo.rs
index 15d0ea0..b0a2d48 100644
--- a/crates/socket-patch-core/src/patch/vendor/cargo.rs
+++ b/crates/socket-patch-core/src/patch/vendor/cargo.rs
@@ -142,6 +142,24 @@ async fn cargo_service_copy(
                 );
             }
             let _ = tokio::fs::remove_file(copy_dir.join(".cargo-checksum.json")).await;
+            // Verify the EXTRACTED TREE, not just the archive bytes: the SRI
+            // proves the download is intact, but an unexpected internal
+            // layout (the single `{name}-{version}/` strip leaving an extra
+            // wrapper, or an over-strip) lands the patched files at the wrong
+            // paths and the caller would synthesize success from
+            // `record.files` while the copy is wrong. Fail closed → `auto`
+            // falls back to the local build. (Mirrors composer_lock.rs.)
+            if !copy_matches_after_hashes(copy_dir, &record.files).await {
+                let _ = remove_tree(copy_dir).await;
+                return miss(
+                    warnings,
+                    "vendor_prebuilt_layout_mismatch",
+                    format!(
+                        "prebuilt crate for {name} extracted to an unexpected \
+                         layout (patched files absent at their recorded paths)"
+                    ),
+                );
+            }
             warnings.push(VendorWarning::new(
                 "vendor_prebuilt_downloaded",
                 format!(
diff --git a/crates/socket-patch-core/src/patch/vendor/composer_lock.rs b/crates/socket-patch-core/src/patch/vendor/composer_lock.rs
index b03ad79..bb5d7fd 100644
--- a/crates/socket-patch-core/src/patch/vendor/composer_lock.rs
+++ b/crates/socket-patch-core/src/patch/vendor/composer_lock.rs
@@ -538,6 +538,30 @@ async fn composer_service_copy(
                     format!("cannot extract the prebuilt dist zip: {e}"),
                 );
             }
+            // Verify the EXTRACTED TREE, not just the archive bytes. The
+            // archive-bytes SRI (checked in fetch_verified_archive) proves
+            // the download is intact, but says nothing about whether the
+            // internal layout lands the patched files at the paths the
+            // record names: a zip with an unexpected wrapper dir (the
+            // single-level `strip_first` leaves an extra `pkg-<sha>/`
+            // segment) or a root-level `src/…` (over-stripped) extracts
+            // "successfully" with every file at the WRONG path. Without
+            // this check the caller synthesized success purely from
+            // `record.files` and shipped a copy missing its patched files
+            // (exit 0, empty copy_dir on disk). Fail closed here and let
+            // the `auto` source fall back to the local build.
+            if !copy_matches_after_hashes(copy_dir, &record.files).await {
+                let _ = remove_tree(copy_dir).await;
+                return miss(
+                    warnings,
+                    "vendor_prebuilt_layout_mismatch",
+                    format!(
+                        "prebuilt dist zip for {pkg} extracted to an \
+                         unexpected layout (patched files absent at their \
+                         recorded paths)"
+                    ),
+                );
+            }
             warnings.push(VendorWarning::new(
                 "vendor_prebuilt_downloaded",
                 format!(
@@ -1501,6 +1525,106 @@ mod tests {
             .any(|w| w.code == "vendor_prebuilt_downloaded"));
     }
 
+    /// Wrong internal layout (double wrapper → the single-level strip
+    /// misplaces the patched file) must NOT be reported as success from
+    /// `record.files` alone. Under `service` mode it hard-fails
+    /// `vendor_prebuilt_layout_mismatch`; the file is not at the expected
+    /// path. Regression for the exit-0-empty-copy incident (run 29040958337).
+    #[tokio::test]
+    async fn service_wrong_layout_service_mode_hard_fails() {
+        let lock = lock_value("psr/log", "3.0.2", false);
+        let (dir, blobs, installed, record) = fixture(&lock).await;
+        let root = dir.path();
+        // A double wrapper: single strip_first leaves `extra/src/...`, so the
+        // patched file never lands at `copy_dir/src/LoggerInterface.php`.
+        let zip = make_dist_zip(
+            "outer-wrapper",
+            &[("extra/src/LoggerInterface.php", PATCHED)],
+        );
+        let sri = sri_sha512(&zip);
+        let server = wiremock::MockServer::start().await;
+        mount_composer_granted(&server, &sri, &zip).await;
+
+        let outcome = vendor_with_service(
+            root,
+            &blobs,
+            &installed,
+            &record,
+            &composer_service_cfg(&server.uri(), VendorSource::Service, false),
+        )
+        .await;
+        // Service mode has no fallback, so `miss()` surfaces the uniform
+        // `vendor_prebuilt_required` code (same as an integrity mismatch);
+        // the layout diagnosis rides in the detail. The point of the
+        // regression is that it REFUSES rather than synthesizing success —
+        // and the copy dir does not hold the file at its recorded path.
+        match outcome {
+            VendorOutcome::Refused { code, detail } => {
+                assert_eq!(code, "vendor_prebuilt_required");
+                assert!(
+                    detail.contains("unexpected layout"),
+                    "the refusal must diagnose the layout mismatch: {detail}"
+                );
+            }
+            other => panic!("expected a refusal, got {other:?}"),
+        }
+        assert!(
+            tokio::fs::metadata(root.join(copy_rel()).join("src/LoggerInterface.php"))
+                .await
+                .is_err(),
+            "the misplaced service copy must not be left at the recorded path"
+        );
+    }
+
+    /// Same wrong-layout archive under `auto`: the guard trips and the local
+    /// build takes over, producing a correct copy — success WITHOUT the bad
+    /// service bytes.
+    #[tokio::test]
+    async fn service_wrong_layout_auto_falls_back_to_build() {
+        let lock = lock_value("psr/log", "3.0.2", false);
+        let (dir, blobs, installed, record) = fixture(&lock).await;
+        let root = dir.path();
+        let zip = make_dist_zip(
+            "outer-wrapper",
+            &[("extra/src/LoggerInterface.php", PATCHED)],
+        );
+        let sri = sri_sha512(&zip);
+        let server = wiremock::MockServer::start().await;
+        mount_composer_granted(&server, &sri, &zip).await;
+
+        let (result, entry, warnings) = unwrap_done(
+            vendor_with_service(
+                root,
+                &blobs,
+                &installed,
+                &record,
+                &composer_service_cfg(&server.uri(), VendorSource::Auto, false),
+            )
+            .await,
+        );
+        assert!(
+            result.success,
+            "auto must fall back to the local build when the service layout \
+             is wrong: {:?}",
+            result.error
+        );
+        assert!(entry.is_some());
+        // The copy holds the patched bytes at the RIGHT path (from the local
+        // build, not the misplaced service extract).
+        assert_eq!(
+            tokio::fs::read(root.join(copy_rel()).join("src/LoggerInterface.php"))
+                .await
+                .unwrap(),
+            PATCHED
+        );
+        assert!(
+            warnings
+                .iter()
+                .any(|w| w.code == "vendor_prebuilt_layout_mismatch"),
+            "the fallback must record why the service copy was rejected: {warnings:?}"
+        );
+    }
+
     /// `service` mode + integrity mismatch hard-fails, nothing extracted.
     #[tokio::test]
     async fn service_integrity_mismatch_service_mode_hard_fails() {
diff --git a/crates/socket-patch-core/src/patch/vendor/gem.rs b/crates/socket-patch-core/src/patch/vendor/gem.rs
index f19acf6..43f6dfb 100644
--- a/crates/socket-patch-core/src/patch/vendor/gem.rs
+++ b/crates/socket-patch-core/src/patch/vendor/gem.rs
@@ -685,6 +685,24 @@ async fn gem_service_copy(
             format!("cannot write the stub gemspec into the vendored dir: {e}"),
         );
     }
+    // Verify the EXTRACTED data.tar.gz tree, not just the .gem bytes: the
+    // SRI proves the download is intact, but an unexpected internal layout
+    // lands the patched files at the wrong paths and the caller would
+    // synthesize success from `record.files` while the copy is wrong. (The
+    // stub gemspec we just wrote is not in record.files, so it is not part
+    // of this check.) Fail closed → `auto` falls back to the local build.
+    // (Mirrors composer_lock.rs.)
+    if !copy_matches_after_hashes(copy_dir, &record.files).await {
+        let _ = remove_tree(uuid_dir).await;
+        return miss(
+            warnings,
+            "vendor_prebuilt_layout_mismatch",
+            format!(
+                "prebuilt .gem for {name} extracted to an unexpected layout \
+                 (patched files absent at their recorded paths)"
+            ),
+        );
+    }
     warnings.push(VendorWarning::new(
         "vendor_prebuilt_downloaded",
         format!(
diff --git a/crates/socket-patch-core/src/patch/vendor/golang.rs b/crates/socket-patch-core/src/patch/vendor/golang.rs
index 6eaf2c2..547a9af 100644
--- a/crates/socket-patch-core/src/patch/vendor/golang.rs
+++ b/crates/socket-patch-core/src/patch/vendor/golang.rs
@@ -418,6 +418,26 @@ async fn go_service_redirect(
                     format!("cannot synthesize go.mod for the copy: {e}"),
                 );
             }
+            // Verify the EXTRACTED TREE before wiring the consumer's go.mod:
+            // the SRI proves the zip bytes are intact, but an unexpected
+            // internal layout (the `{module}@{version}/` prefix strip
+            // mismatching) lands the patched files at the wrong paths, and
+            // the caller would synthesize success from `record.files` while
+            // the copy is wrong. Fail closed → `auto` falls back to the
+            // local build; do it BEFORE editing go.mod so nothing points at
+            // a bad copy. (Mirrors composer_lock.rs.)
+            if !copy_matches_after_hashes(copy_dir, &record.files).await {
+                teardown_failed_service_copy(project_root, base_rel, module, wired).await;
+                return miss(
+                    warnings,
+                    "vendor_prebuilt_layout_mismatch",
+                    format!(
+                        "prebuilt module zip for {module} extracted to an \
+                         unexpected layout (patched files absent at their \
+                         recorded paths)"
+                    ),
+                );
+            }
             if let Err(e) =
                 go_mod_edit::ensure_replace_entry(project_root, module, version, base_rel, false)
                     .await