1use std::collections::HashMap;
4use std::path::Path;
5use std::sync::Mutex;
6use std::time::SystemTime;
7
8use chrono::{DateTime, Utc};
9use lru::LruCache;
10
11use crate::error::SessionStoreError;
12use crate::sessions_root;
13
14const MANIFEST_CACHE_CAPACITY: usize = 200;
15const MANIFEST_CACHE_NONZERO_CAPACITY: std::num::NonZeroUsize =
16 std::num::NonZeroUsize::new(MANIFEST_CACHE_CAPACITY).unwrap();
17static MANIFEST_CACHE: std::sync::OnceLock<Mutex<LruCache<String, CachedManifest>>> = std::sync::OnceLock::new();
18
19#[derive(Debug, Clone)]
20struct CachedManifest {
21 summary: SessionSummary,
22 signature: ManifestSignature,
23}
24
25#[derive(Debug, Clone, Copy, PartialEq, Eq)]
26struct ManifestSignature {
27 modified: Option<SystemTime>,
28 len: u64,
29}
30
31fn manifest_signature(path: &Path) -> Option<ManifestSignature> {
32 let metadata = std::fs::symlink_metadata(path).ok()?;
33 Some(ManifestSignature {
34 modified: metadata.modified().ok(),
35 len: metadata.len(),
36 })
37}
38
39pub(crate) fn invalidate_manifest_cache(path: &Path) {
41 if let Some(cache) = MANIFEST_CACHE.get()
42 && let Ok(mut cache) = cache.lock()
43 {
44 let key = path.to_string_lossy();
45 cache.pop(key.as_ref());
46 }
47}
48
49#[derive(Debug, Clone, serde::Serialize, serde::Deserialize, PartialEq, Eq)]
51pub struct SessionSummary {
52 pub session_id: String,
54 pub turn_count: u64,
56 pub event_count: u64,
58 pub status: String,
60 pub updated_at: String,
62}
63
64#[derive(Debug, Clone, serde::Serialize, serde::Deserialize, PartialEq, Eq)]
66pub struct FactRecord {
67 pub fact: String,
69 pub session_id: String,
71}
72
73#[derive(Debug, Clone, serde::Serialize, serde::Deserialize, PartialEq)]
79pub struct MemorySearchResult {
80 chunk_id: String,
82 path: String,
84 start_line: usize,
86 end_line: usize,
88 score: f64,
90 snippet: String,
92 source: String,
94 created_at: Option<i64>,
96}
97
98#[must_use]
100pub fn recent_sessions(workspace: &Path, n: usize) -> Vec<SessionSummary> {
101 let root = sessions_root(workspace);
102 if !root.exists() {
103 return Vec::new();
104 }
105 let mut out = Vec::new();
106 let entries = match std::fs::read_dir(&root) {
107 Ok(e) => e,
108 Err(_) => return Vec::new(),
109 };
110 let mut cache = MANIFEST_CACHE
111 .get_or_init(|| Mutex::new(LruCache::new(MANIFEST_CACHE_NONZERO_CAPACITY)))
112 .lock()
113 .unwrap_or_else(std::sync::PoisonError::into_inner);
114 for entry in entries.filter_map(Result::ok) {
115 let manifest = entry.path().join("manifest.json");
116 let key = manifest.to_string_lossy().into_owned();
117 let signature = manifest_signature(&manifest);
118 if let Some(cached) = cache.get(&key)
119 && signature == Some(cached.signature)
120 {
121 out.push(cached.summary.clone());
122 continue;
123 }
124 if let Ok(bytes) = std::fs::read(&manifest)
125 && let Ok(s) = serde_json::from_slice::<SessionSummary>(&bytes)
126 {
127 if let Some(signature) = signature.or_else(|| manifest_signature(&manifest)) {
128 cache.put(key, CachedManifest { summary: s.clone(), signature });
129 }
130 out.push(s);
131 }
132 }
133 out.sort_by(|a, b| b.updated_at.cmp(&a.updated_at));
134 out.truncate(n);
135 out
136}
137
138pub fn query_facts(workspace: &Path, limit: usize) -> Result<Vec<FactRecord>, SessionStoreError> {
142 let root = sessions_root(workspace);
143 if !root.exists() {
144 return Ok(Vec::new());
145 }
146 let mut facts: Vec<FactRecord> = Vec::new();
147 let entries = std::fs::read_dir(&root).map_err(|e| SessionStoreError::io(root.clone(), e))?;
148 for entry in entries.filter_map(Result::ok) {
149 let memory = entry.path().join(crate::DERIVED_DIR).join("memory.json");
150 let Ok(bytes) = std::fs::read(&memory) else {
151 continue;
152 };
153 let Ok(value) = serde_json::from_slice::<serde_json::Value>(&bytes) else {
154 continue;
155 };
156 let session_id = entry.file_name().to_string_lossy().into_owned();
157 if let Some(arr) = value.get("grounded_facts").and_then(|v| v.as_array()) {
158 for item in arr {
159 if let Some(fact) = item.get("fact").and_then(|f| f.as_str()) {
160 facts.push(FactRecord {
161 fact: fact.to_string(),
162 session_id: session_id.clone(),
163 });
164 }
165 }
166 }
167 }
168 facts.truncate(limit);
169 Ok(facts)
170}
171
172pub fn search_memory(
179 workspace: &Path,
180 query: &str,
181 max_results: usize,
182 min_score: f64,
183) -> Result<Vec<MemorySearchResult>, SessionStoreError> {
184 if query.is_empty() {
185 return Ok(Vec::new());
186 }
187
188 let root = sessions_root(workspace);
189 if !root.exists() {
190 return Ok(Vec::new());
191 }
192
193 let query_terms = tokenize(query);
194 if query_terms.is_empty() {
195 return Ok(Vec::new());
196 }
197 let mut results: Vec<MemorySearchResult> = Vec::new();
198 let session_source = String::from("session");
199 let mut documents = Vec::new();
200
201 let entries = std::fs::read_dir(&root).map_err(|e| SessionStoreError::io(root.clone(), e))?;
202 for entry in entries.filter_map(Result::ok) {
203 let session_dir = entry.path();
204 let memory = session_dir.join(crate::DERIVED_DIR).join("memory.json");
205 let Ok(bytes) = std::fs::read(&memory) else {
206 continue;
207 };
208 let Ok(value) = serde_json::from_slice::<serde_json::Value>(&bytes) else {
209 continue;
210 };
211 let session_id = entry.file_name().to_string_lossy().into_owned();
212 let memory_path = memory.to_string_lossy().into_owned();
213 let created_at = value
214 .get("created_at")
215 .and_then(parse_timestamp)
216 .or_else(|| value.get("updated_at").and_then(parse_timestamp));
217
218 if let Some(arr) = value.get("grounded_facts").and_then(|v| v.as_array()) {
219 for (idx, item) in arr.iter().enumerate() {
220 let Some(fact) = item.get("fact").and_then(|f| f.as_str()) else {
221 continue;
222 };
223 documents.push((
224 format!("{session_id}:{idx}"),
225 memory_path.clone(),
226 fact.to_owned(),
227 tokenize(fact),
228 created_at,
229 ));
230 }
231 }
232 }
233
234 let document_count = documents.len();
235 if document_count == 0 {
236 return Ok(Vec::new());
237 }
238 let average_length =
239 documents.iter().map(|(_, _, _, terms, _)| terms.len() as f64).sum::<f64>() / document_count as f64;
240 let mut document_frequency: HashMap<String, usize> = HashMap::new();
241 for (_, _, _, terms, _) in &documents {
242 let mut seen = std::collections::HashSet::new();
243 for term in terms {
244 if seen.insert(term.as_str()) {
245 *document_frequency.entry(term.clone()).or_insert(0) += 1;
246 }
247 }
248 }
249 let k1 = 1.2;
250 let b = 0.75;
251 let now = Utc::now();
252 for (chunk_id, path, fact, terms, created_at) in documents {
253 let length = terms.len() as f64;
254 let mut term_frequency = HashMap::<&str, usize>::new();
255 for term in &terms {
256 *term_frequency.entry(term.as_str()).or_insert(0) += 1;
257 }
258 let mut score = 0.0;
259 for query_term in &query_terms {
260 let Some(&frequency) = term_frequency.get(query_term.as_str()) else {
261 continue;
262 };
263 let Some(&frequency_in_documents) = document_frequency.get(query_term) else {
264 continue;
265 };
266 let idf = (((document_count - frequency_in_documents) as f64 + 0.5)
267 / (frequency_in_documents as f64 + 0.5)
268 + 1.0)
269 .ln();
270 let denominator = frequency as f64 + k1 * (1.0 - b + b * length / average_length.max(1.0));
271 score += idf * (frequency as f64 * (k1 + 1.0)) / denominator;
272 }
273 if score <= 0.0 {
274 continue;
275 }
276 score *= recency_multiplier(created_at, now);
281 if score < min_score {
282 continue;
283 }
284 results.push(MemorySearchResult {
285 chunk_id,
286 path,
287 start_line: 0,
288 end_line: 0,
289 score,
290 snippet: fact,
291 source: session_source.clone(),
292 created_at,
293 });
294 }
295
296 results.sort_by(|a, b| {
297 b.score
298 .partial_cmp(&a.score)
299 .unwrap_or(std::cmp::Ordering::Equal)
300 .then_with(|| a.chunk_id.cmp(&b.chunk_id))
301 });
302 results.truncate(max_results);
303 Ok(results)
304}
305
306fn parse_timestamp(value: &serde_json::Value) -> Option<i64> {
307 if let Some(timestamp) = value.as_i64() {
308 return DateTime::<Utc>::from_timestamp(timestamp, 0).map(|_| timestamp);
309 }
310 let text = value.as_str()?.trim();
311 if let Ok(timestamp) = text.parse::<i64>() {
312 return DateTime::<Utc>::from_timestamp(timestamp, 0).map(|_| timestamp);
313 }
314 DateTime::parse_from_rfc3339(text).ok().map(|timestamp| timestamp.timestamp())
315}
316
317fn recency_multiplier(created_at: Option<i64>, now: DateTime<Utc>) -> f64 {
318 let Some(created_at) = created_at.and_then(|timestamp| DateTime::<Utc>::from_timestamp(timestamp, 0)) else {
319 return 1.0;
320 };
321 let age_days = (now - created_at).num_seconds().max(0) as f64 / 86_400.0;
322 1.0 + 0.15 * 0.5_f64.powf(age_days / 30.0)
323}
324
325pub fn default_search_max_results() -> usize {
327 6
328}
329
330pub fn default_search_min_score() -> f64 {
332 0.0
333}
334
335fn count_substring_matches(text: &str, lowered_query: &str) -> usize {
336 if lowered_query.is_empty() {
337 return 0;
338 }
339 let lowered = text.to_ascii_lowercase();
340 let mut count = 0;
341 let mut start = 0;
342 while let Some(pos) = lowered[start..].find(lowered_query) {
343 count += 1;
344 start += pos + lowered_query.len();
345 }
346 count
347}
348
349fn tokenize(text: &str) -> Vec<String> {
350 let mut tokens = Vec::new();
351 let mut current = String::new();
352 for character in text.chars() {
353 if character.is_alphanumeric() {
354 current.extend(character.to_lowercase());
355 } else if !current.is_empty() {
356 tokens.push(std::mem::take(&mut current));
357 }
358 }
359 if !current.is_empty() {
360 tokens.push(current);
361 }
362 tokens
363}
364
365#[derive(Debug, Clone, serde::Serialize, serde::Deserialize, PartialEq, Eq)]
372pub struct SessionMemoryView {
373 pub summary: String,
375 pub facts: Vec<String>,
377}
378
379pub fn write_session_memory_view(
387 workspace: &Path,
388 session_id: &str,
389 view: &SessionMemoryView,
390) -> Result<(), SessionStoreError> {
391 let dir = crate::session_dir(workspace, session_id);
392 crate::ensure_private_directory(&dir)?;
393 crate::ensure_private_directory(&dir.join(crate::DERIVED_DIR))?;
394
395 let envelope = serde_json::json!({
396 "session_id": session_id,
397 "schema_version": 3,
398 "summary": view.summary,
399 "grounded_facts": view
400 .facts
401 .iter()
402 .map(|fact| serde_json::json!({ "fact": fact }))
403 .collect::<Vec<_>>(),
404 "touched_files": [],
405 "generated_at": Utc::now().to_rfc3339(),
406 });
407 let bytes = serde_json::to_vec_pretty(&envelope)
408 .map_err(|error| SessionStoreError::io(dir.clone(), std::io::Error::other(error)))?;
409 let dest = dir.join(crate::DERIVED_DIR).join("memory.json");
410 vtcode_commons::VtCodePaths::write_private_file_atomic(&dest, &bytes)
411 .map_err(|error| SessionStoreError::io(dest, std::io::Error::other(error)))?;
412 invalidate_manifest_cache(&dir.join("manifest.json"));
413 Ok(())
414}
415
416pub fn session_memory_facts(
421 workspace: &Path,
422 session_id: &str,
423 limit: usize,
424) -> Result<Vec<FactRecord>, SessionStoreError> {
425 let memory = crate::session_dir(workspace, session_id)
426 .join(crate::DERIVED_DIR)
427 .join("memory.json");
428 let Ok(bytes) = std::fs::read(&memory) else {
429 return Ok(Vec::new());
430 };
431 let Ok(value) = serde_json::from_slice::<serde_json::Value>(&bytes) else {
432 return Ok(Vec::new());
433 };
434 let mut facts = Vec::new();
435 if let Some(arr) = value.get("grounded_facts").and_then(|v| v.as_array()) {
436 for item in arr {
437 if let Some(fact) = item.get("fact").and_then(|f| f.as_str()) {
438 facts.push(FactRecord {
439 fact: fact.to_string(),
440 session_id: session_id.to_string(),
441 });
442 if facts.len() >= limit {
443 break;
444 }
445 }
446 }
447 }
448 Ok(facts)
449}
450
451#[cfg(test)]
452mod tests {
453 use super::*;
454 use tempfile::TempDir;
455
456 #[test]
457 fn count_substring_matches_counts_overlapping() {
458 assert_eq!(count_substring_matches("aaaa", "aa"), 2);
459 assert_eq!(count_substring_matches("ababa", "aba"), 1);
460 assert_eq!(count_substring_matches("hello world", "ll"), 1);
461 assert_eq!(count_substring_matches("", "x"), 0);
462 }
463
464 #[test]
465 fn search_memory_returns_matching_facts() {
466 let dir = TempDir::new().expect("tempdir");
467 let sess = crate::session_dir(dir.path(), "s1");
468 std::fs::create_dir_all(sess.join(crate::DERIVED_DIR)).expect("mkdir");
469 let memory = serde_json::json!({
470 "grounded_facts": [
471 {"fact": "the widget is blue"},
472 {"fact": "the server runs on port 8080"},
473 {"fact": "use PostgreSQL for persistence"},
474 ]
475 });
476 std::fs::write(sess.join(crate::DERIVED_DIR).join("memory.json"), serde_json::to_string(&memory).expect("ser"))
477 .expect("write");
478
479 let results = search_memory(dir.path(), "blue", 10, 0.0).expect("search");
480 assert_eq!(results.len(), 1);
481 assert_eq!(results[0].snippet, "the widget is blue");
482 assert_eq!(results[0].chunk_id, "s1:0");
483 assert!(results[0].score > 0.0);
484 }
485
486 #[test]
487 fn search_memory_scores_multiple_matches() {
488 let dir = TempDir::new().expect("tempdir");
489 let sess = crate::session_dir(dir.path(), "s2");
490 std::fs::create_dir_all(sess.join(crate::DERIVED_DIR)).expect("mkdir");
491 let memory = serde_json::json!({
492 "grounded_facts": [
493 {"fact": "rust uses rustc and cargo"},
494 {"fact": "cargo is the rust build tool"},
495 ]
496 });
497 std::fs::write(sess.join(crate::DERIVED_DIR).join("memory.json"), serde_json::to_string(&memory).expect("ser"))
498 .expect("write");
499
500 let results = search_memory(dir.path(), "cargo", 10, 0.0).expect("search");
501 assert_eq!(results.len(), 2);
502 assert!(results.iter().all(|r| r.score > 0.0));
503 }
504
505 #[test]
506 fn search_memory_respects_min_score() {
507 let dir = TempDir::new().expect("tempdir");
508 let sess = crate::session_dir(dir.path(), "s3");
509 std::fs::create_dir_all(sess.join(crate::DERIVED_DIR)).expect("mkdir");
510 let memory = serde_json::json!({
511 "grounded_facts": [
512 {"fact": "alpha beta gamma"},
513 ]
514 });
515 std::fs::write(sess.join(crate::DERIVED_DIR).join("memory.json"), serde_json::to_string(&memory).expect("ser"))
516 .expect("write");
517
518 let results = search_memory(dir.path(), "beta", 10, 2.0).expect("search");
519 assert!(results.is_empty());
520 }
521
522 #[test]
523 fn search_memory_empty_query_returns_empty() {
524 let dir = TempDir::new().expect("tempdir");
525 let results = search_memory(dir.path(), "", 10, 0.0).expect("search");
526 assert!(results.is_empty());
527 }
528
529 #[test]
530 fn search_memory_sorts_by_score_descending() {
531 let dir = TempDir::new().expect("tempdir");
532 for i in 0..3 {
533 let sess = crate::session_dir(dir.path(), &format!("s{i}"));
534 std::fs::create_dir_all(sess.join(crate::DERIVED_DIR)).expect("mkdir");
535 let memory = serde_json::json!({
536 "grounded_facts": [
537 {"fact": format!("fact {i} appears twice twice")},
538 ]
539 });
540 std::fs::write(
541 sess.join(crate::DERIVED_DIR).join("memory.json"),
542 serde_json::to_string(&memory).expect("ser"),
543 )
544 .expect("write");
545 }
546
547 let results = search_memory(dir.path(), "twice", 10, 0.0).expect("search");
548 assert_eq!(results.len(), 3);
549 assert!(results.windows(2).all(|w| w[0].score >= w[1].score));
550 }
551
552 #[test]
553 fn search_memory_uses_bm25_term_coverage_and_deterministic_ties() {
554 let dir = TempDir::new().expect("tempdir");
555 for (session_id, facts) in [
556 ("s1", vec!["rust cargo tool", "unrelated note"]),
557 ("s2", vec!["cargo build tool"]),
558 ] {
559 let session = crate::session_dir(dir.path(), session_id);
560 std::fs::create_dir_all(session.join(crate::DERIVED_DIR)).expect("mkdir");
561 let memory = serde_json::json!({
562 "grounded_facts": facts.into_iter().map(|fact| serde_json::json!({"fact": fact})).collect::<Vec<_>>()
563 });
564 std::fs::write(
565 session.join(crate::DERIVED_DIR).join("memory.json"),
566 serde_json::to_string(&memory).expect("serialize"),
567 )
568 .expect("write");
569 }
570
571 let results = search_memory(dir.path(), "rust cargo", 10, 0.0).expect("search");
572 assert_eq!(results.first().map(|result| result.chunk_id.as_str()), Some("s1:0"));
573 assert!(results[0].score > results[1].score);
574 }
575
576 #[test]
577 fn search_memory_applies_recency_to_valid_rfc3339_timestamps() {
578 let dir = TempDir::new().expect("tempdir");
579 for (session_id, timestamp) in [("old", "2020-01-01T00:00:00Z"), ("new", "2099-01-01T00:00:00Z")] {
580 let session = crate::session_dir(dir.path(), session_id);
581 std::fs::create_dir_all(session.join(crate::DERIVED_DIR)).expect("mkdir");
582 let memory = serde_json::json!({
583 "created_at": timestamp,
584 "grounded_facts": [{"fact": "shared search fact"}]
585 });
586 std::fs::write(
587 session.join(crate::DERIVED_DIR).join("memory.json"),
588 serde_json::to_vec(&memory).expect("serialize"),
589 )
590 .expect("write");
591 }
592
593 let results = search_memory(dir.path(), "shared", 10, 0.0).expect("search");
594 assert_eq!(results.len(), 2);
595 assert_eq!(results[0].chunk_id, "new:0");
596 assert!(results[0].score > results[1].score);
597 }
598
599 #[test]
600 fn search_memory_does_not_boost_missing_or_invalid_timestamps() {
601 let dir = TempDir::new().expect("tempdir");
602 for (session_id, timestamp) in [
603 ("missing", serde_json::Value::Null),
604 ("invalid", serde_json::json!("not-a-date")),
605 ] {
606 let session = crate::session_dir(dir.path(), session_id);
607 std::fs::create_dir_all(session.join(crate::DERIVED_DIR)).expect("mkdir");
608 let mut memory = serde_json::json!({"grounded_facts": [{"fact": "neutral search fact"}]});
609 if !timestamp.is_null() {
610 memory["created_at"] = timestamp;
611 }
612 std::fs::write(
613 session.join(crate::DERIVED_DIR).join("memory.json"),
614 serde_json::to_vec(&memory).expect("serialize"),
615 )
616 .expect("write");
617 }
618
619 let results = search_memory(dir.path(), "neutral", 10, 0.0).expect("search");
620 assert_eq!(results.len(), 2);
621 assert!((results[0].score - results[1].score).abs() < f64::EPSILON);
622 assert_eq!(results[0].created_at, None);
623 assert_eq!(results[1].created_at, None);
624 }
625
626 #[test]
627 fn recency_multiplier_matches_thirty_day_half_life() {
628 let now = DateTime::parse_from_rfc3339("2026-01-31T00:00:00Z")
629 .expect("timestamp")
630 .with_timezone(&Utc);
631 let thirty_days_ago = now - chrono::Duration::days(30);
632 let multiplier = recency_multiplier(Some(thirty_days_ago.timestamp()), now);
633 assert!((multiplier - 1.075).abs() < 1e-12);
634 assert!((recency_multiplier(None, now) - 1.0).abs() < f64::EPSILON);
635 }
636
637 #[test]
638 fn recent_sessions_invalidates_manifest_cache_after_replacement() {
639 let dir = TempDir::new().expect("tempdir");
640 let session = crate::session_dir(dir.path(), "cache-session");
641 std::fs::create_dir_all(&session).expect("mkdir");
642 let manifest = serde_json::json!({
643 "session_id": "cache-session",
644 "schema_version": 1,
645 "created_at": "2026-01-01T00:00:00Z",
646 "updated_at": "2026-01-01T00:00:00Z",
647 "turn_count": 1,
648 "event_count": 1,
649 "status": "active"
650 });
651 let path = session.join("manifest.json");
652 std::fs::write(&path, serde_json::to_vec(&manifest).expect("serialize")).expect("write");
653 assert_eq!(recent_sessions(dir.path(), 1)[0].updated_at, "2026-01-01T00:00:00Z");
654
655 let mut replaced = manifest;
656 replaced["updated_at"] = serde_json::json!("2099-01-01T00:00:00Z");
657 std::fs::write(&path, serde_json::to_vec(&replaced).expect("serialize")).expect("replace");
658 assert_eq!(recent_sessions(dir.path(), 1)[0].updated_at, "2099-01-01T00:00:00Z");
659 }
660
661 #[test]
662 fn session_memory_view_round_trips_through_queries() {
663 let dir = TempDir::new().expect("tempdir");
664 let view = SessionMemoryView {
665 summary: "Implemented the frobnicator".to_string(),
666 facts: vec![
667 "Uses tokio for async runtime".to_string(),
668 "Prefers anyhow errors".to_string(),
669 ],
670 };
671 write_session_memory_view(dir.path(), "view-session", &view).expect("write view");
672
673 let facts = session_memory_facts(dir.path(), "view-session", 10).expect("read facts");
674 assert_eq!(facts.len(), 2);
675 assert_eq!(facts[0].session_id, "view-session");
676 assert_eq!(facts[0].fact, "Uses tokio for async runtime");
677
678 let all = query_facts(dir.path(), 10).expect("query facts");
679 assert_eq!(all.len(), 2);
680 assert!(all.iter().all(|record| record.session_id == "view-session"));
681
682 let results = search_memory(dir.path(), "tokio", 5, 0.0).expect("search");
683 assert_eq!(results.len(), 1);
684 assert!(results[0].snippet.contains("tokio"));
685 }
686
687 #[test]
688 fn session_memory_facts_respects_limit_and_missing_files() {
689 let dir = TempDir::new().expect("tempdir");
690 assert!(
691 session_memory_facts(dir.path(), "missing-session", 5)
692 .expect("missing")
693 .is_empty()
694 );
695
696 let view = SessionMemoryView {
697 summary: String::new(),
698 facts: (0..5).map(|index| format!("fact-{index}")).collect(),
699 };
700 write_session_memory_view(dir.path(), "limited", &view).expect("write");
701 let limited = session_memory_facts(dir.path(), "limited", 3).expect("read");
702 assert_eq!(limited.len(), 3);
703 assert_eq!(limited[2].fact, "fact-2");
704 }
705}