Name session checkpoints by their session title

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/app.rs

@@ -228,6 +228,8 @@ impl App {
                     // Before the counters are taken, so they measure what is
                     // actually reachable.
                     sweep_orphan_checkpoints(&kv_cache_path(), &projects);
+                    #[cfg(target_os = "macos")]
+                    crate::engine::sweep_transient_cache(&transient_cache_path());
                     let context_limit = preferences.context_tokens.max(0) as u32;
                     // Reopen on the project we left, with a fresh draft chat.
                     let last_project = preferences

src/app/generation.rs

@@ -552,8 +552,7 @@ impl App {
         false
     }
 
-    #[cfg(target_os = "macos")]
-    fn session_title(&self, session_id: i32) -> Option<String> {
+    pub(super) fn session_title(&self, session_id: i32) -> Option<String> {
         self.projects
             .iter()
             .flat_map(|project| &project.sessions)

src/app/view/stats.rs

@@ -417,9 +417,16 @@ impl App {
         let mut rows = column![].spacing(7);
         for entry in &usage.entries {
             let path = entry.path.clone();
+            let label = entry
+                .session
+                .and_then(|id| self.session_title(id))
+                .map_or_else(
+                    || entry.name.clone(),
+                    |title| format!("{}: {}", entry.name, shorten(&title)),
+                );
             rows = rows.push(
                 row![
-                    text(entry.name.clone()).size(12),
+                    text(label).size(12),
                     Space::with_width(Length::Fill),
                     text(format!(
                         "{} · {} old",
@@ -499,6 +506,15 @@ const AGE_COLORS: [Color; 5] = [
     Color::from_rgb(0.45, 0.45, 0.48),
 ];
 
+/// Keeps a long session title from crowding out the size and the action.
+fn shorten(title: &str) -> String {
+    const LIMIT: usize = 44;
+    if title.chars().count() <= LIMIT {
+        return title.to_owned();
+    }
+    title.chars().take(LIMIT - 1).chain(['…']).collect()
+}
+
 fn portion(bytes: u64, capacity: u64) -> u16 {
     ((bytes.saturating_mul(1000) / capacity.max(1)) as u16).max(1)
 }

src/engine.rs

@@ -26,6 +26,8 @@ use validation::{validate_dspark, validate_main};
 
 pub(crate) use validation::validate_model_artifact;
 
+#[cfg(target_os = "macos")]
+pub(crate) use kvstore::sweep_unreachable as sweep_transient_cache;
 #[cfg(target_os = "macos")]
 pub(crate) use metal::configure_sources as configure_metal_sources;
 

src/engine/kvstore.rs

@@ -1,5 +1,6 @@
 use sha2::{Digest, Sha256};
 use std::cmp::Ordering;
+use std::collections::HashSet;
 use std::fs::{self, File};
 use std::io::{Read, Write};
 use std::path::{Path, PathBuf};
@@ -68,6 +69,8 @@ impl KvStore {
             directory: directory.to_owned(),
             budget_bytes,
         };
+        // Reclaim first, so the budget is measured against the whole directory.
+        sweep_unreachable(directory);
         // A lowered budget takes effect at once, like ds4's eviction on open.
         store.evict(None);
         Ok(store)
@@ -174,6 +177,41 @@ impl KvStore {
     }
 }
 
+/// Deletes what the index cannot reach: a checkpoint whose index is missing or
+/// unreadable can never be found, and an index whose checkpoint is gone is
+/// dead weight. Without this, an interrupted store or a checkpoint written
+/// before the index existed occupies disc that eviction cannot even see, and
+/// the directory grows past the budget unnoticed.
+pub(crate) fn sweep_unreachable(directory: &Path) {
+    let Ok(files) = fs::read_dir(directory) else {
+        return;
+    };
+    let reachable = files
+        .filter_map(Result::ok)
+        .map(|file| file.path())
+        .filter(|path| path.extension().is_some_and(|value| value == "meta"))
+        .filter_map(|path| read_entry(&path).ok())
+        .filter(|entry| entry.checkpoint.is_file())
+        .map(|entry| entry.checkpoint)
+        .collect::<HashSet<_>>();
+    let Ok(files) = fs::read_dir(directory) else {
+        return;
+    };
+    for file in files.flatten() {
+        let path = file.path();
+        let dead = match path.extension().and_then(|value| value.to_str()) {
+            Some("bin") => !reachable.contains(&path),
+            Some("meta") => !reachable.contains(&path.with_extension("bin")),
+            // Staging files from an interrupted index write.
+            Some("tmp") => true,
+            _ => false,
+        };
+        if dead {
+            let _ = fs::remove_file(&path);
+        }
+    }
+}
+
 fn eviction_score(entry: &Entry, now: u64) -> f64 {
     let age = now.saturating_sub(entry.last_used.max(entry.created_at)) as f64;
     let hits = f64::from(entry.hits) * f64::exp2(-age / HIT_HALF_LIFE_SECONDS);
@@ -364,6 +402,29 @@ mod tests {
         fs::remove_dir_all(directory).unwrap();
     }
 
+    #[test]
+    fn opening_reclaims_checkpoints_the_index_cannot_reach() {
+        let directory = temporary_directory("unreachable");
+        let store = KvStore::open(&directory, GIB).unwrap();
+        let indexed = add(&store, b"indexed", 100, 32);
+        let stray = directory.join("deadbeef.bin");
+        let widow = directory.join("widow.meta");
+        let staging = directory.join("indexed.meta.tmp");
+        fs::write(&stray, vec![0; 4_096]).unwrap();
+        fs::write(&widow, vec![0; 64]).unwrap();
+        fs::write(&staging, vec![0; 64]).unwrap();
+
+        KvStore::open(&directory, GIB).unwrap();
+
+        assert!(indexed.checkpoint.is_file());
+        assert!(index_path(&indexed.checkpoint).is_file());
+        assert!(!stray.exists());
+        assert!(!widow.exists());
+        assert!(!staging.exists());
+
+        fs::remove_dir_all(directory).unwrap();
+    }
+
     #[test]
     fn budget_evicts_the_least_valuable_unprotected_entry() {
         let directory = temporary_directory("evict");

src/metrics.rs

@@ -694,6 +694,8 @@ const CACHE_ENTRY_ROWS: usize = 12;
 pub(crate) struct KvCacheEntry {
     pub(crate) path: PathBuf,
     pub(crate) name: String,
+    /// Set for session checkpoints, so the view can name the conversation.
+    pub(crate) session: Option<i32>,
     pub(crate) bytes: u64,
     pub(crate) age_seconds: u64,
 }
@@ -762,6 +764,10 @@ pub(crate) fn kv_cache_report(root: &Path, budget_bytes: u64) -> KvCacheReport {
             }
             report.entries.push(KvCacheEntry {
                 name: entry_name(&path, transient),
+                session: (!transient)
+                    .then(|| path.file_stem().and_then(|value| value.to_str()))
+                    .flatten()
+                    .and_then(|stem| stem.parse().ok()),
                 bytes: bytes.saturating_add(
                     fs::metadata(path.with_extension("meta")).map_or(0, |index| index.len()),
                 ),
@@ -924,6 +930,9 @@ mod tests {
         assert_eq!(report.entries.len(), 2);
         assert_eq!(report.entries[0].bytes, 140);
         assert_eq!(report.entries[1].name, "Session 7");
+        // The session id survives on the row, so the view can add its title.
+        assert_eq!(report.entries[1].session, Some(7));
+        assert_eq!(report.entries[0].session, None);
 
         fs::remove_dir_all(root).unwrap();
     }