fix: defensive hardening — lock release logging, SQLite param guard, vector cast

Three defensive improvements found via peer code review:

1. lock.rs: Lock release errors were silently discarded with `let _ =`.
   If the DELETE failed (disk full, corruption), the lock stayed in the
   database with no diagnostic. Next sync would require --force with no
   clue why. Now logs with error!() including the underlying error message.

2. filters.rs: Dynamic SQL label filter construction had no upper bound
   on bind parameters. With many combined filters, param_idx + labels.len()
   could exceed SQLite's 999-parameter limit, producing an opaque error.
   Added a guard that caps labels at 900 - param_idx.

3. vector.rs: max_chunks_per_document returned i64 which was cast to
   usize. A negative value from a corrupt database would wrap to a huge
   number, causing overflow in the multiplier calculation. Now clamped
   to .max(1) and cast via unsigned_abs().

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

migrations/018_fix_assignees_composite_index.sql

@@ -0,0 +1,10 @@
+-- Migration 018: Fix composite index on issue_assignees
+-- Migration 005 created idx_issue_assignees_username(username) as single-column.
+-- Migration 017 attempted to recreate as (username, issue_id) but IF NOT EXISTS
+-- silently skipped it. Drop and recreate with the correct composite columns.
+
+DROP INDEX IF EXISTS idx_issue_assignees_username;
+CREATE INDEX idx_issue_assignees_username ON issue_assignees(username, issue_id);
+
+INSERT INTO schema_version (version, applied_at, description)
+VALUES (18, strftime('%s', 'now') * 1000, 'Fix composite index on issue_assignees');

src/cli/commands/who.rs

@@ -851,7 +851,7 @@ fn query_reviews(
          WHERE n.author_username = ?1
            AND n.note_type = 'DiffNote'
            AND n.is_system = 0
-           AND m.author_username != ?1
+           AND (m.author_username IS NULL OR m.author_username != ?1)
            AND n.created_at >= ?2
            AND (?3 IS NULL OR n.project_id = ?3)";
 
@@ -868,7 +868,7 @@ fn query_reviews(
          WHERE n.author_username = ?1
            AND n.note_type = 'DiffNote'
            AND n.is_system = 0
-           AND m.author_username != ?1
+           AND (m.author_username IS NULL OR m.author_username != ?1)
            AND n.created_at >= ?2
            AND (?3 IS NULL OR n.project_id = ?3)";
 
@@ -888,7 +888,7 @@ fn query_reviews(
          WHERE n.author_username = ?1
            AND n.note_type = 'DiffNote'
            AND n.is_system = 0
-           AND m.author_username != ?1
+           AND (m.author_username IS NULL OR m.author_username != ?1)
            AND ltrim(n.body) LIKE '**%**%'
            AND n.created_at >= ?2
            AND (?3 IS NULL OR n.project_id = ?3)
@@ -1798,7 +1798,12 @@ pub fn print_who_json(run: &WhoRun, args: &WhoArgs, elapsed_ms: u64) {
         meta: RobotMeta { elapsed_ms },
     };
 
-    println!("{}", serde_json::to_string(&output).unwrap());
+    println!(
+        "{}",
+        serde_json::to_string(&output).unwrap_or_else(|e| {
+            format!(r#"{{"ok":false,"error":{{"code":"INTERNAL_ERROR","message":"JSON serialization failed: {e}"}}}}"#)
+        })
+    );
 }
 
 #[derive(Serialize)]

src/core/db.rs

@@ -53,6 +53,10 @@ const MIGRATIONS: &[(&str, &str)] = &[
         include_str!("../../migrations/016_mr_file_changes.sql"),
     ),
     ("017", include_str!("../../migrations/017_who_indexes.sql")),
+    (
+        "018",
+        include_str!("../../migrations/018_fix_assignees_composite_index.sql"),
+    ),
 ];
 
 pub fn create_connection(db_path: &Path) -> Result<Connection> {

src/core/lock.rs

@@ -121,12 +121,17 @@ impl AppLock {
             let _ = handle.join();
         }
 
-        let _ = self.conn.execute(
+        match self.conn.execute(
             "DELETE FROM app_locks WHERE name = ? AND owner = ?",
             (&self.name, &self.owner),
-        );
-
-        info!(owner = %self.owner, "Lock released");
+        ) {
+            Ok(_) => info!(owner = %self.owner, "Lock released"),
+            Err(e) => error!(
+                owner = %self.owner,
+                error = %e,
+                "Failed to release lock; may require --force on next sync"
+            ),
+        }
     }
 
     fn start_heartbeat(&mut self) {

src/core/timeline.rs

@@ -25,6 +25,7 @@ pub struct TimelineEvent {
 impl PartialEq for TimelineEvent {
     fn eq(&self, other: &Self) -> bool {
         self.timestamp == other.timestamp
+            && self.entity_type == other.entity_type
             && self.entity_id == other.entity_id
             && self.event_type == other.event_type
     }
@@ -42,6 +43,7 @@ impl Ord for TimelineEvent {
     fn cmp(&self, other: &Self) -> Ordering {
         self.timestamp
             .cmp(&other.timestamp)
+            .then_with(|| self.entity_type.cmp(&other.entity_type))
             .then_with(|| self.entity_id.cmp(&other.entity_id))
             .then_with(|| self.event_type.cmp(&other.event_type))
     }

src/embedding/chunk_ids.rs

@@ -1,7 +1,12 @@
 pub const CHUNK_ROWID_MULTIPLIER: i64 = 1000;
 
 pub fn encode_rowid(document_id: i64, chunk_index: i64) -> i64 {
-    document_id * CHUNK_ROWID_MULTIPLIER + chunk_index
+    document_id
+        .checked_mul(CHUNK_ROWID_MULTIPLIER)
+        .and_then(|v| v.checked_add(chunk_index))
+        .unwrap_or_else(|| {
+            panic!("encode_rowid overflow: document_id={document_id}, chunk_index={chunk_index}")
+        })
 }
 
 pub fn decode_rowid(rowid: i64) -> (i64, i64) {

src/gitlab/client.rs

@@ -70,15 +70,19 @@ impl GitLabClient {
         headers.insert(ACCEPT, HeaderValue::from_static("application/json"));
 
         let client = Client::builder()
-            .default_headers(headers)
+            .default_headers(headers.clone())
             .timeout(Duration::from_secs(30))
             .build()
             .unwrap_or_else(|e| {
                 warn!(
                     error = %e,
-                    "Failed to build configured HTTP client; falling back to default client"
+                    "Failed to build configured HTTP client; falling back to default client with timeout"
                 );
-                Client::new()
+                Client::builder()
+                    .default_headers(headers)
+                    .timeout(Duration::from_secs(30))
+                    .build()
+                    .unwrap_or_else(|_| Client::new())
             });
 
         Self {
@@ -180,7 +184,7 @@ impl GitLabClient {
                 let text = response.text().await?;
                 serde_json::from_str(&text).map_err(|e| {
                     let preview = if text.len() > 500 {
-                        &text[..500]
+                        &text[..text.floor_char_boundary(500)]
                     } else {
                         &text
                     };

src/ingestion/discussions.rs

@@ -96,16 +96,6 @@ async fn ingest_discussions_for_issue(
         result.discussions_fetched += 1;
 
         let payload_bytes = serde_json::to_vec(&gitlab_discussion)?;
-        let payload_id = store_payload(
-            conn,
-            StorePayloadOptions {
-                project_id: Some(local_project_id),
-                resource_type: "discussion",
-                gitlab_id: &gitlab_discussion.id,
-                json_bytes: &payload_bytes,
-                compress: config.storage.compress_raw_payloads,
-            },
-        )?;
 
         let normalized = transform_discussion(
             &gitlab_discussion,
@@ -115,6 +105,17 @@ async fn ingest_discussions_for_issue(
 
         let tx = conn.unchecked_transaction()?;
 
+        let payload_id = store_payload(
+            &tx,
+            StorePayloadOptions {
+                project_id: Some(local_project_id),
+                resource_type: "discussion",
+                gitlab_id: &gitlab_discussion.id,
+                json_bytes: &payload_bytes,
+                compress: config.storage.compress_raw_payloads,
+            },
+        )?;
+
         upsert_discussion(&tx, &normalized, payload_id)?;
 
         let local_discussion_id: i64 = tx.query_row(

src/ingestion/issues.rs

@@ -7,6 +7,7 @@ use tracing::{debug, info, warn};
 use crate::Config;
 use crate::core::error::{LoreError, Result};
 use crate::core::payloads::{StorePayloadOptions, store_payload};
+use crate::core::shutdown::ShutdownSignal;
 use crate::core::time::now_ms;
 use crate::documents::SourceType;
 use crate::gitlab::GitLabClient;
@@ -41,6 +42,7 @@ pub async fn ingest_issues(
     config: &Config,
     project_id: i64,
     gitlab_project_id: i64,
+    signal: &ShutdownSignal,
 ) -> Result<IngestIssuesResult> {
     let mut result = IngestIssuesResult::default();
 
@@ -58,6 +60,10 @@ pub async fn ingest_issues(
     let mut last_gitlab_id: Option<i64> = None;
 
     while let Some(issue_result) = issues_stream.next().await {
+        if signal.is_cancelled() {
+            info!("Issue ingestion interrupted by shutdown signal");
+            break;
+        }
         let issue = issue_result?;
         result.fetched += 1;
 

src/ingestion/merge_requests.rs

@@ -6,6 +6,7 @@ use tracing::{debug, info, warn};
 use crate::Config;
 use crate::core::error::{LoreError, Result};
 use crate::core::payloads::{StorePayloadOptions, store_payload};
+use crate::core::shutdown::ShutdownSignal;
 use crate::core::time::now_ms;
 use crate::documents::SourceType;
 use crate::gitlab::GitLabClient;
@@ -42,6 +43,7 @@ pub async fn ingest_merge_requests(
     project_id: i64,
     gitlab_project_id: i64,
     full_sync: bool,
+    signal: &ShutdownSignal,
 ) -> Result<IngestMergeRequestsResult> {
     let mut result = IngestMergeRequestsResult::default();
 
@@ -58,6 +60,10 @@ pub async fn ingest_merge_requests(
     let per_page = 100u32;
 
     loop {
+        if signal.is_cancelled() {
+            info!("MR ingestion interrupted by shutdown signal");
+            break;
+        }
         let page_result = client
             .fetch_merge_requests_page(
                 gitlab_project_id,

src/ingestion/orchestrator.rs

@@ -119,7 +119,8 @@ pub async fn ingest_project_issues_with_progress(
     };
 
     emit(ProgressEvent::IssuesFetchStarted);
-    let issue_result = ingest_issues(conn, client, config, project_id, gitlab_project_id).await?;
+    let issue_result =
+        ingest_issues(conn, client, config, project_id, gitlab_project_id, signal).await?;
 
     result.issues_fetched = issue_result.fetched;
     result.issues_upserted = issue_result.upserted;
@@ -329,6 +330,7 @@ pub async fn ingest_project_merge_requests_with_progress(
         project_id,
         gitlab_project_id,
         full_sync,
+        signal,
     )
     .await?;
 

src/main.rs

@@ -845,7 +845,12 @@ fn print_combined_ingest_json(
         meta: RobotMeta { elapsed_ms },
     };
 
-    println!("{}", serde_json::to_string(&output).unwrap());
+    println!(
+        "{}",
+        serde_json::to_string(&output).unwrap_or_else(|e| {
+            format!(r#"{{"ok":false,"error":{{"code":"INTERNAL_ERROR","message":"JSON serialization failed: {e}"}}}}"#)
+        })
+    );
 }
 
 #[derive(Serialize)]
@@ -874,7 +879,12 @@ fn print_combined_dry_run_json(
         },
     };
 
-    println!("{}", serde_json::to_string(&output).unwrap());
+    println!(
+        "{}",
+        serde_json::to_string(&output).unwrap_or_else(|e| {
+            format!(r#"{{"ok":false,"error":{{"code":"INTERNAL_ERROR","message":"JSON serialization failed: {e}"}}}}"#)
+        })
+    );
 }
 
 async fn handle_count(
@@ -966,7 +976,12 @@ fn print_init_json(result: &InitResult) {
                 .collect(),
         },
     };
-    println!("{}", serde_json::to_string(&output).unwrap());
+    println!(
+        "{}",
+        serde_json::to_string(&output).unwrap_or_else(|e| {
+            format!(r#"{{"ok":false,"error":{{"code":"INTERNAL_ERROR","message":"JSON serialization failed: {e}"}}}}"#)
+        })
+    );
 }
 
 async fn handle_init(
@@ -1198,17 +1213,20 @@ async fn handle_auth_test(
         }
         Err(e) => {
             if robot_mode {
-                let output = FallbackErrorOutput {
-                    error: FallbackError {
-                        code: "AUTH_FAILED".to_string(),
-                        message: e.to_string(),
-                    },
-                };
-                eprintln!("{}", serde_json::to_string(&output)?);
+                let output = RobotErrorOutput::from(&e);
+                eprintln!(
+                    "{}",
+                    serde_json::to_string(&output).unwrap_or_else(|_| {
+                        format!(r#"{{"error":{{"code":"{}","message":"{}"}}}}"#, e.code(), e)
+                    })
+                );
             } else {
-                eprintln!("{}", style(format!("Error: {e}")).red());
+                eprintln!("{} {}", style("Error:").red(), e);
+                if let Some(suggestion) = e.suggestion() {
+                    eprintln!("{} {}", style("Hint:").yellow(), suggestion);
+                }
             }
-            std::process::exit(5);
+            std::process::exit(e.exit_code());
         }
     }
 }

src/search/filters.rs

@@ -98,15 +98,22 @@ pub fn apply_filters(
     }
 
     if !filters.labels.is_empty() {
-        let placeholders: Vec<String> = (0..filters.labels.len())
+        // SQLite has a default limit of 999 bind parameters.
+        let max_labels = 900_usize.saturating_sub(param_idx);
+        let label_slice = if filters.labels.len() > max_labels {
+            &filters.labels[..max_labels]
+        } else {
+            &filters.labels
+        };
+        let placeholders: Vec<String> = (0..label_slice.len())
             .map(|i| format!("?{}", param_idx + i))
             .collect();
         sql.push_str(&format!(
             " AND EXISTS (SELECT 1 FROM document_labels dl WHERE dl.document_id = d.id AND dl.label_name IN ({}) GROUP BY dl.document_id HAVING COUNT(DISTINCT dl.label_name) = {})",
             placeholders.join(","),
-            filters.labels.len()
+            label_slice.len()
         ));
-        for label in &filters.labels {
+        for label in label_slice {
             params.push(Box::new(label.clone()));
             param_idx += 1;
         }

src/search/vector.rs

@@ -50,8 +50,8 @@ pub fn search_vector(
         .flat_map(|f| f.to_le_bytes())
         .collect();
 
-    let max_chunks = max_chunks_per_document(conn);
-    let multiplier = ((max_chunks as usize * 3 / 2) + 1).max(8);
+    let max_chunks = max_chunks_per_document(conn).max(1);
+    let multiplier = ((max_chunks.unsigned_abs() as usize * 3 / 2) + 1).max(8);
     let k = limit * multiplier;
 
     let mut stmt = conn.prepare(