Preserve semantic reader after failed generation rebuild

crates/searchi-service/src/lib.rs

@@ -289,22 +289,36 @@ impl HybridSearch {
     /// storage errors leave the previous generation active. A crashed build is
     /// reclaimed on the next explicit rebuild under an OS advisory lock.
     pub fn index_embeddings(&mut self) -> Result<EmbeddingReport> {
-        let previous_fingerprint = self.generation_fingerprint.clone();
-        self.generation_fingerprint = format!(
+        let fingerprint = format!(
             "{}:text-only",
             generation_fingerprint(self.embedder.fingerprint())
         );
+        self.rebuild_generation(fingerprint, Self::build)
+    }
+
+    /// Keep the reader's policy aligned with the active generation on every
+    /// failure boundary, including lock admission, activation and cleanup.
+    fn rebuild_generation(
+        &mut self,
+        fingerprint: String,
+        build: impl FnOnce(&mut Self, i64) -> Result<EmbeddingReport>,
+    ) -> Result<EmbeddingReport> {
         let _lock = self.store.build_lock()?;
-        let generation = self.store.begin(&self.generation_fingerprint)?;
-        let built = self.build(generation);
+        let generation = self.store.begin(&fingerprint)?;
+        let previous_fingerprint = std::mem::replace(&mut self.generation_fingerprint, fingerprint);
+        let built = build(self, generation).and_then(|report| {
+            self.store.activate(generation)?;
+            Ok(report)
+        });
         match built {
-            Ok(report) => {
-                self.store.activate(generation)?;
-                Ok(report)
-            }
+            Ok(report) => Ok(report),
             Err(error) => {
-                self.store.abandon(generation)?;
                 self.generation_fingerprint = previous_fingerprint;
+                if let Err(cleanup) = self.store.abandon(generation) {
+                    return Err(error.context(format!(
+                        "Failed to discard staging generation {generation}: {cleanup:#}"
+                    )));
+                }
                 Err(error)
             }
         }

crates/searchi-service/src/media.rs

@@ -17,8 +17,7 @@ impl HybridSearch {
         tools: &FfmpegTools,
         limits: &MediaLimits,
     ) -> Result<EmbeddingReport> {
-        let previous_fingerprint = self.generation_fingerprint.clone();
-        self.generation_fingerprint = generation_fingerprint(self.embedder.fingerprint());
+        let mut fingerprint = generation_fingerprint(self.embedder.fingerprint());
         let defaults = MediaLimits::default();
         if limits.max_frames != defaults.max_frames
             || limits.frame_interval_ms != defaults.frame_interval_ms
@@ -29,7 +28,7 @@ impl HybridSearch {
             || limits.max_duration_ms != defaults.max_duration_ms
             || limits.max_file_bytes != defaults.max_file_bytes
         {
-            self.generation_fingerprint.push_str(&format!(
+            fingerprint.push_str(&format!(
                 ":custom-{}-{}-{}-{}-{}-{}-{}-{}",
                 limits.max_frames,
                 limits.frame_interval_ms,
@@ -41,14 +40,12 @@ impl HybridSearch {
                 limits.max_file_bytes
             ));
         }
-        let _lock = self.store.build_lock()?;
-        let generation = self.store.begin(&self.generation_fingerprint)?;
-        let built = (|| {
-            let mut report = self.build(generation)?;
+        self.rebuild_generation(fingerprint, |service, generation| {
+            let mut report = service.build(generation)?;
             let mut after = 0;
             let mut media_count = 0usize;
             loop {
-                let files = self.store.media_batch(after)?;
+                let files = service.store.media_batch(after)?;
                 if files.is_empty() {
                     break;
                 }
@@ -64,7 +61,7 @@ impl HybridSearch {
                         "Media generation exceeds 10000-file resource budget"
                     );
                     let before_chunks = report.chunks;
-                    match self.build_media_file(
+                    match service.build_media_file(
                         generation,
                         id,
                         path,
@@ -78,7 +75,7 @@ impl HybridSearch {
                             if error.downcast_ref::<InferenceFailure>().is_some() {
                                 return Err(error);
                             }
-                            self.store.media_failure(
+                            service.store.media_failure(
                                 generation,
                                 &path.to_string_lossy(),
                                 &format!("{error:#}"),
@@ -96,18 +93,7 @@ impl HybridSearch {
                 }
             }
             Ok(report)
-        })();
-        match built {
-            Ok(report) => {
-                self.store.activate(generation)?;
-                Ok(report)
-            }
-            Err(error) => {
-                self.store.abandon(generation)?;
-                self.generation_fingerprint = previous_fingerprint;
-                Err(error)
-            }
-        }
+        })
     }
 
     #[allow(clippy::too_many_arguments)]