1package core
2
3import (
4 "bufio"
5 "bytes"
6 "context"
7 "encoding/json"
8 "errors"
9 "fmt"
10 "io"
11 "os"
12 "path/filepath"
13 "sort"
14 "strings"
15 "time"
16
17 "github.com/bnema/zut/packages/provider"
18 "github.com/google/uuid"
19)
20
21// PortableExt is the filesystem extension used for exported sessions.
22// A ".zutsession" is just a zut JSONL session file with the meta
23// header rewritten so the importing user gets fresh ownership.
24const PortableExt = ".zutsession"
25
26// ExportSession writes the session at srcPath to dstPath as a
27// portable .zutsession file. If dstPath is an existing directory the
28// file is created inside it with a name derived from the session's
29// meta ("YYYYMMDD-HHMMSS-<first-prompt-excerpt>.zutsession"). The
30// destination's directory is created if needed. Returns the final
31// resolved path so the caller can tell the user where it landed.
32//
33// The on-disk format is unchanged from a live session; only the
34// meta.cwd is stripped of its per-machine prefix (the importing
35// user doesn't care what directory it came from). Everything else
36// round-trips byte-for-byte.
37func ExportSession(srcPath, dstPath string) (string, error) {
38 if srcPath == "" {
39 return "", errors.New("export: source path is empty")
40 }
41 if dstPath == "" {
42 return "", errors.New("export: destination path is empty")
43 }
44
45 // Read the effective snapshot so a later model/provider update is not
46 // replaced by the stale metadata in the first row.
47 snapshot, err := ReadSessionSnapshot(srcPath)
48 if err != nil {
49 return "", fmt.Errorf("export: read session snapshot: %w", err)
50 }
51
52 // Read the source meta up-front so we can name the output sensibly
53 // when dstPath is a directory, and so we can validate it's a real
54 // session before starting to write.
55 src, err := os.Open(srcPath)
56 if err != nil {
57 return "", fmt.Errorf("export: open source: %w", err)
58 }
59 defer src.Close()
60
61 sc := bufio.NewScanner(src)
62 sc.Buffer(make([]byte, 0, 64*1024), 20*1024*1024)
63 if !sc.Scan() {
64 return "", errors.New("export: session file is empty")
65 }
66 var head sessionLine
67 if err := json.Unmarshal(sc.Bytes(), &head); err != nil {
68 return "", fmt.Errorf("export: parse meta: %w", err)
69 }
70 if head.Type != "meta" || head.Meta == nil {
71 return "", errors.New("export: first line is not a meta row")
72 }
73
74 // Scan the rest of the file for the first user message so we can
75 // build a humane filename. Only reads if dstPath doesn't already
76 // end in .zutsession.
77 firstPrompt := ""
78 if !strings.HasSuffix(strings.ToLower(dstPath), PortableExt) {
79 if fi, _ := os.Stat(dstPath); fi == nil || fi.IsDir() {
80 p, err := firstUserPrompt(src)
81 if err != nil {
82 return "", fmt.Errorf("export: read first prompt: %w", err)
83 }
84 firstPrompt = p
85 }
86 }
87
88 // Resolve dstPath: if it's a directory, build a name inside it.
89 outPath := dstPath
90 if fi, err := os.Stat(dstPath); err == nil && fi.IsDir() {
91 name := filenameFor(head.Meta.Started, head.Meta.ID, firstPrompt)
92 outPath = filepath.Join(dstPath, name)
93 } else if !strings.HasSuffix(strings.ToLower(outPath), PortableExt) {
94 outPath += PortableExt
95 }
96
97 // Re-open the source from the top since we advanced the scanner.
98 if _, err := src.Seek(0, io.SeekStart); err != nil {
99 return "", fmt.Errorf("export: rewind: %w", err)
100 }
101
102 if err := os.MkdirAll(filepath.Dir(outPath), 0o755); err != nil {
103 return "", fmt.Errorf("export: mkdir dst: %w", err)
104 }
105 dst, err := os.OpenFile(outPath, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0o644)
106 if err != nil {
107 return "", fmt.Errorf("export: create dst: %w", err)
108 }
109 defer dst.Close()
110 bw := bufio.NewWriter(dst)
111
112 // Rewrite the meta row: strip the cwd (the importing user has
113 // their own) and keep everything else identical. ID stays so the
114 // export is traceable; the importer will rotate to a fresh ID.
115 exportMeta := snapshot.Meta
116 exportMeta.CWD = ""
117 metaLine, err := json.Marshal(sessionLine{Type: "meta", Meta: &exportMeta})
118 if err != nil {
119 return "", fmt.Errorf("export: marshal meta: %w", err)
120 }
121 if _, err := bw.Write(metaLine); err != nil {
122 return "", err
123 }
124 if err := bw.WriteByte('\n'); err != nil {
125 return "", err
126 }
127
128 // Stream every non-meta row verbatim. Use ReadBytes instead of
129 // bufio.Scanner: large sessions can contain very long JSONL rows
130 // (image blocks, big tool outputs, compacted history) that exceed
131 // Scanner's token limit and fail with "token too long".
132 r := bufio.NewReader(src)
133 for {
134 line, err := r.ReadBytes('\n')
135 if len(line) > 0 {
136 line = bytes.TrimRight(line, "\r\n")
137 var h sessionLineHead
138 if err := json.Unmarshal(line, &h); err == nil && h.Type != "meta" {
139 if _, werr := bw.Write(line); werr != nil {
140 return "", werr
141 }
142 if werr := bw.WriteByte('\n'); werr != nil {
143 return "", werr
144 }
145 }
146 }
147 if err == io.EOF {
148 break
149 }
150 if err != nil {
151 return "", fmt.Errorf("export: read source: %w", err)
152 }
153 }
154 if err := bw.Flush(); err != nil {
155 return "", err
156 }
157 return outPath, nil
158}
159
160// ImportSession copies the .zutsession file at srcPath into the
161// running user's session store under the given root+cwd, rewriting
162// the meta's id / cwd / started fields so the imported session is
163// owned by the current user / directory / clock. Returns the path
164// of the created session file, ready to pass to OpenSession.
165//
166// The imported session is a first-class zut session: it'll show up
167// in /sessions, /jump, and on-disk summaries just like any other.
168// Messages and usage rows are preserved verbatim.
169func ImportSession(srcPath, root, cwd, version string) (string, error) {
170 if srcPath == "" {
171 return "", errors.New("import: source path is empty")
172 }
173 src, err := os.Open(srcPath)
174 if err != nil {
175 return "", fmt.Errorf("import: open source: %w", err)
176 }
177 defer src.Close()
178
179 // Read the effective metadata before committing to a destination. Meta
180 // rows are append-only, so the first row may describe an older provider or
181 // model after a runtime switch.
182 snapshot, err := ReadSessionSnapshot(srcPath)
183 if err != nil {
184 return "", fmt.Errorf("import: read session snapshot: %w", err)
185 }
186
187 // Validate the file header before committing to a destination.
188 sc := bufio.NewScanner(src)
189 sc.Buffer(make([]byte, 0, 64*1024), 20*1024*1024)
190 if !sc.Scan() {
191 return "", errors.New("import: session file is empty")
192 }
193 var head sessionLine
194 if err := json.Unmarshal(sc.Bytes(), &head); err != nil {
195 return "", fmt.Errorf("import: parse meta: %w", err)
196 }
197 if head.Type != "meta" || head.Meta == nil {
198 return "", errors.New("import: first line is not a meta row")
199 }
200
201 // Build the destination inside the current cwd's session dir
202 // with a fresh timestamped name.
203 dir := SessionsDir(root, cwd)
204 if err := os.MkdirAll(dir, 0o755); err != nil {
205 return "", err
206 }
207 newID := uuid.NewString()
208 name := fmt.Sprintf("%s-%s.jsonl", time.Now().UTC().Format("20060102-150405"), newID[:8])
209 outPath := filepath.Join(dir, name)
210 dst, err := os.OpenFile(outPath, os.O_CREATE|os.O_EXCL|os.O_WRONLY, 0o644)
211 if err != nil {
212 return "", fmt.Errorf("import: create dst: %w", err)
213 }
214 defer dst.Close()
215 bw := bufio.NewWriter(dst)
216
217 // Write a fresh meta row claiming ownership.
218 now := time.Now()
219 timezone, timezoneOffset := localTimeMetadata(now)
220 importMeta := SessionMeta{
221 ID: newID,
222 CWD: cwd,
223 Model: snapshot.Meta.Model,
224 Provider: snapshot.Meta.Provider,
225 Started: now.UTC(),
226 Version: version,
227 Title: snapshot.Title,
228 Timezone: timezone,
229 TimezoneOffset: timezoneOffset,
230 CompactHandoff: append(json.RawMessage(nil), snapshot.Meta.CompactHandoff...),
231 Mission: cloneSessionMission(snapshot.Meta.Mission),
232 Goal: cloneSessionGoal(snapshot.Meta.Goal),
233 GoalHistory: cloneGoalHistory(snapshot.Meta.GoalHistory),
234 }
235 metaLine, err := json.Marshal(sessionLine{Type: "meta", Meta: &importMeta})
236 if err != nil {
237 return "", fmt.Errorf("import: marshal meta: %w", err)
238 }
239 if _, err := bw.Write(metaLine); err != nil {
240 return "", err
241 }
242 if err := bw.WriteByte('\n'); err != nil {
243 return "", err
244 }
245
246 // Rewind the source and stream every non-meta row. Avoid
247 // bufio.Scanner so exported sessions with huge JSONL rows import
248 // cleanly.
249 if _, err := src.Seek(0, io.SeekStart); err != nil {
250 return "", fmt.Errorf("import: rewind: %w", err)
251 }
252 if err := forEachJSONLLine(src, func(line []byte) error {
253 var h sessionLineHead
254 if err := json.Unmarshal(line, &h); err != nil || h.Type == "meta" {
255 return nil
256 }
257 if _, err := bw.Write(line); err != nil {
258 return err
259 }
260 return bw.WriteByte('\n')
261 }); err != nil {
262 return "", fmt.Errorf("import: read source: %w", err)
263 }
264 if err := bw.Flush(); err != nil {
265 return "", err
266 }
267 return outPath, nil
268}
269
270// BranchSession creates a new session in root/cwd that contains the
271// parent's messages 0..upToMessageIdx-1 (i.e. the first N user+
272// assistant+tool rows). The new meta records Parent=<parent id> and
273// ForkPoint=N so /session tree can rebuild the branch topology
274// later. The effective repaired prefix is materialized, and all eligible
275// usage checkpoints at or before the cut are preserved so the running cost
276// tracker can reconstruct the final-turn delta. A boundary that ends on a
277// tool call is extended through its paired tool result.
278//
279// upToMessageIdx is a count over the flat message stream as
280// returned by OpenSession. To "branch at user turn 3" the caller
281// passes the index of that user message in msgs + 1 (so the
282// message itself is included). The caller figures that out; this
283// helper rejects a count outside the current effective snapshot.
284//
285// Returns the path of the new session file, ready for OpenSession.
286func BranchSession(parentPath, root, cwd, version string, upToMessageIdx int) (string, error) {
287 return branchSession(parentPath, root, cwd, version, upToMessageIdx, false)
288}
289
290// BranchSessionHidden creates a branch that participates in /session tree but
291// is hidden from the flat /sessions picker. Used for in-place tree navigation.
292func BranchSessionHidden(parentPath, root, cwd, version string, upToMessageIdx int) (string, error) {
293 return branchSession(parentPath, root, cwd, version, upToMessageIdx, true)
294}
295
296func branchSession(parentPath, root, cwd, version string, upToMessageIdx int, hideFromSessions bool) (string, error) {
297 if parentPath == "" {
298 return "", errors.New("branch: parent path is empty")
299 }
300 if upToMessageIdx < 0 {
301 return "", errors.New("branch: upToMessageIdx must be >= 0")
302 }
303
304 snapshot, err := ReadSessionSnapshot(parentPath)
305 if err != nil {
306 return "", fmt.Errorf("branch: read parent snapshot: %w", err)
307 }
308 if upToMessageIdx > len(snapshot.Messages) {
309 return "", fmt.Errorf("branch: upToMessageIdx %d exceeds effective message count %d", upToMessageIdx, len(snapshot.Messages))
310 }
311
312 // A tool-call row is not a safe provider boundary by itself. Accept the
313 // convenient row index used by existing callers, but extend it through the
314 // immediately paired tool result when necessary. Orphan calls already have
315 // a synthetic result in the shared snapshot.
316 limit := upToMessageIdx
317 if limit > 0 && limit < len(snapshot.Messages) && messageHasToolCalls(snapshot.Messages[limit-1]) && snapshot.Messages[limit].Role == provider.RoleTool {
318 limit++
319 }
320
321 extensionState, err := readExtensionStateAtFork(parentPath, limit)
322 if err != nil {
323 return "", err
324 }
325 compactHandoff := compactHandoffAtBranch(snapshot.Meta, snapshot.Messages, limit)
326 goal := goalAtBranch(snapshot.Meta, snapshot.Messages, limit)
327 return writeBranchSession(root, cwd, version, snapshot.Meta, snapshot.Messages, snapshot.UsageCheckpoints, limit, hideFromSessions, extensionState, compactHandoff, goal)
328}
329
330// BranchSessionHiddenFromHistory creates a hidden tree branch from a
331// pre-compaction transcript segment. The segment is already repaired and is
332// kept separate from the effective snapshot so normal resume semantics remain
333// unchanged while older fork points stay usable.
334func BranchSessionHiddenFromHistory(parentPath, root, cwd, version string, segment SessionHistorySegment, upToMessageIdx int) (string, error) {
335 if parentPath == "" {
336 return "", errors.New("branch: parent path is empty")
337 }
338 if upToMessageIdx < 0 {
339 return "", errors.New("branch: upToMessageIdx must be >= 0")
340 }
341 if upToMessageIdx > len(segment.Messages) {
342 return "", fmt.Errorf("branch: upToMessageIdx %d exceeds historical message count %d", upToMessageIdx, len(segment.Messages))
343 }
344
345 snapshot, err := ReadSessionSnapshot(parentPath)
346 if err != nil {
347 return "", fmt.Errorf("branch: read parent snapshot: %w", err)
348 }
349 limit := upToMessageIdx
350 if limit > 0 && limit < len(segment.Messages) && messageHasToolCalls(segment.Messages[limit-1]) && segment.Messages[limit].Role == provider.RoleTool {
351 limit++
352 }
353 extensionState, err := readExtensionStateAtFork(parentPath, limit)
354 if err != nil {
355 return "", err
356 }
357 return writeBranchSession(root, cwd, version, snapshot.Meta, segment.Messages, segment.UsageCheckpoints, limit, true, extensionState, nil, nil)
358}
359
360// readExtensionStateAtFork reconstructs the latest extension snapshot that was
361// persisted at or before a branch boundary. Extension state is independent of
362// provider messages, but its timeline still follows the effective message
363// stream across compaction rows.
364func readExtensionStateAtFork(path string, limit int) (map[string]json.RawMessage, error) {
365 f, err := os.Open(path)
366 if err != nil {
367 return nil, fmt.Errorf("branch: open parent for extension state: %w", err)
368 }
369 defer f.Close()
370
371 state := make(map[string]json.RawMessage)
372 forkState := make(map[string]json.RawMessage)
373 cloneState := func(source map[string]json.RawMessage) map[string]json.RawMessage {
374 clone := make(map[string]json.RawMessage, len(source))
375 for name, raw := range source {
376 clone[name] = append(json.RawMessage(nil), raw...)
377 }
378 return clone
379 }
380 applyState := func(target map[string]json.RawMessage, row sessionLine) {
381 if len(row.State) == 0 || strings.TrimSpace(string(row.State)) == "null" {
382 delete(target, row.Extension)
383 return
384 }
385 if json.Valid(row.State) {
386 target[row.Extension] = append(json.RawMessage(nil), row.State...)
387 }
388 }
389 effectiveCount := 0
390 err = forEachStrictJSONLLine(f, func(line []byte, lineNo int) error {
391 var head sessionLineHead
392 if err := json.Unmarshal(line, &head); err != nil {
393 return fmt.Errorf("line %d: invalid JSON: %w", lineNo, err)
394 }
395 switch head.Type {
396 case "meta", "usage", "rename":
397 return nil
398 case "message":
399 if _, err := hydrateMessage(line); err != nil {
400 return fmt.Errorf("line %d: invalid message row: %w", lineNo, err)
401 }
402 effectiveCount++
403 case "compaction":
404 messages, err := hydrateCompaction(line)
405 if err != nil {
406 return fmt.Errorf("line %d: invalid compaction row: %w", lineNo, err)
407 }
408 effectiveCount = len(messages)
409 // A compaction replaces the effective transcript. State that was
410 // recorded anywhere before this boundary belongs to every fork
411 // inside the replacement transcript, even when its old message
412 // index was after the requested fork point.
413 forkState = cloneState(state)
414 case "extension_state":
415 var row sessionLine
416 if err := json.Unmarshal(line, &row); err != nil {
417 return fmt.Errorf("line %d: invalid extension state row: %w", lineNo, err)
418 }
419 if row.Extension == "" || len(row.State) > maxExtensionStateBytes {
420 return nil
421 }
422 applyState(state, row)
423 if effectiveCount <= limit {
424 applyState(forkState, row)
425 }
426 default:
427 return fmt.Errorf("line %d: unknown row type %q", lineNo, head.Type)
428 }
429 return nil
430 })
431 if err != nil {
432 return nil, fmt.Errorf("branch: read extension state: %w", err)
433 }
434 return forkState, nil
435}
436
437func compactHandoffAtBranch(parent SessionMeta, messages []provider.Message, limit int) json.RawMessage {
438 if len(parent.CompactHandoff) == 0 || limit != len(messages) {
439 return nil
440 }
441 return append(json.RawMessage(nil), parent.CompactHandoff...)
442}
443
444func goalAtBranch(parent SessionMeta, messages []provider.Message, limit int) *SessionGoal {
445 if limit != len(messages) {
446 return nil
447 }
448 return cloneSessionGoal(parent.Goal)
449}
450
451func missionAtBranch(parent SessionMeta, messages []provider.Message, limit int) *SessionMission {
452 if limit != len(messages) {
453 return nil
454 }
455 return cloneSessionMission(parent.Mission)
456}
457
458func cloneSessionGoal(goal *SessionGoal) *SessionGoal {
459 if goal == nil {
460 return nil
461 }
462 clone := *goal
463 return &clone
464}
465
466func cloneGoalHistory(history []SessionGoal) []SessionGoal {
467 return append([]SessionGoal(nil), history...)
468}
469
470func goalHistoryAtBranch(parent SessionMeta, messages []provider.Message, limit int) []SessionGoal {
471 if limit != len(messages) {
472 return nil
473 }
474 return cloneGoalHistory(parent.GoalHistory)
475}
476
477func writeBranchSession(root, cwd, version string, parent SessionMeta, messages []provider.Message, checkpoints []SessionUsageCheckpoint, limit int, hideFromSessions bool, extensionState map[string]json.RawMessage, compactHandoff json.RawMessage, goal *SessionGoal) (string, error) {
478 dir := SessionsDir(root, cwd)
479 if err := os.MkdirAll(dir, 0o755); err != nil {
480 return "", err
481 }
482 newID := uuid.NewString()
483 name := fmt.Sprintf("%s-%s.jsonl", time.Now().UTC().Format("20060102-150405"), newID[:8])
484 outPath := filepath.Join(dir, name)
485 // Build in a same-directory temporary file. Rename is atomic only when
486 // the temporary and final paths share a directory; closing the file first
487 // also ensures no buffered writer or descriptor can expose a partial branch.
488 dst, err := os.CreateTemp(dir, ".zut-branch-*.tmp")
489 if err != nil {
490 return "", fmt.Errorf("branch: create temp: %w", err)
491 }
492 tmpPath := dst.Name()
493 if err := dst.Chmod(0o644); err != nil {
494 _ = dst.Close()
495 _ = os.Remove(tmpPath)
496 return "", fmt.Errorf("branch: chmod temp: %w", err)
497 }
498 committed := false
499 defer func() {
500 _ = dst.Close()
501 if !committed {
502 _ = os.Remove(tmpPath)
503 _ = os.Remove(outPath)
504 }
505 }()
506 bw := bufio.NewWriter(dst)
507
508 branchMeta := SessionMeta{
509 ID: newID,
510 CWD: cwd,
511 Model: parent.Model,
512 Provider: parent.Provider,
513 Started: time.Now().UTC(),
514 Version: version,
515 Parent: parent.ID,
516 ForkPoint: limit,
517 HideFromSessions: hideFromSessions,
518 CompactHandoff: append(json.RawMessage(nil), compactHandoff...),
519 Mission: missionAtBranch(parent, messages, limit),
520 Goal: cloneSessionGoal(goal),
521 GoalHistory: goalHistoryAtBranch(parent, messages, limit),
522 }
523 metaLine, err := json.Marshal(sessionLine{Type: "meta", Meta: &branchMeta})
524 if err != nil {
525 return "", fmt.Errorf("branch: marshal meta: %w", err)
526 }
527 if _, err := bw.Write(metaLine); err != nil {
528 return "", err
529 }
530 if err := bw.WriteByte('\n'); err != nil {
531 return "", err
532 }
533
534 for idx := 0; idx < limit; idx++ {
535 msg := messages[idx]
536 line, err := json.Marshal(sessionLine{Type: "message", Message: &msg})
537 if err != nil {
538 return "", fmt.Errorf("branch: marshal message %d: %w", idx, err)
539 }
540 if _, err := bw.Write(line); err != nil {
541 return "", err
542 }
543 if err := bw.WriteByte('\n'); err != nil {
544 return "", err
545 }
546 }
547
548 // Extension snapshots are branch state, not provider-visible transcript
549 // content. Write the latest snapshot that existed at the fork point so a
550 // child branch starts from the same extension state as its copied prefix.
551 extensionNames := make([]string, 0, len(extensionState))
552 for name := range extensionState {
553 extensionNames = append(extensionNames, name)
554 }
555 sort.Strings(extensionNames)
556 for _, name := range extensionNames {
557 line, err := json.Marshal(sessionLine{Type: "extension_state", Extension: name, State: extensionState[name]})
558 if err != nil {
559 return "", fmt.Errorf("branch: marshal extension state: %w", err)
560 }
561 if _, err := bw.Write(line); err != nil {
562 return "", fmt.Errorf("branch: write extension state: %w", err)
563 }
564 if err := bw.WriteByte('\n'); err != nil {
565 return "", fmt.Errorf("branch: terminate extension state row: %w", err)
566 }
567 }
568 // Preserve every cumulative checkpoint that belongs to this prefix. The
569 // final two rows are needed to reconstruct LastTurnUsage as a delta.
570 for _, checkpoint := range checkpoints {
571 if checkpoint.MessageCount > limit {
572 continue
573 }
574 usageLine, err := json.Marshal(sessionLine{
575 Type: "usage",
576 Usage: &checkpoint.Cumulative,
577 Cumulative: &checkpoint.Cumulative,
578 })
579 if err != nil {
580 return "", fmt.Errorf("branch: marshal usage: %w", err)
581 }
582 if _, err := bw.Write(usageLine); err != nil {
583 return "", err
584 }
585 if err := bw.WriteByte('\n'); err != nil {
586 return "", err
587 }
588 }
589
590 if err := bw.Flush(); err != nil {
591 return "", err
592 }
593 if err := dst.Sync(); err != nil {
594 return "", fmt.Errorf("branch: sync temp: %w", err)
595 }
596 if err := dst.Close(); err != nil {
597 return "", fmt.Errorf("branch: close temp: %w", err)
598 }
599 if err := os.Rename(tmpPath, outPath); err != nil {
600 return "", fmt.Errorf("branch: commit: %w", err)
601 }
602 committed = true
603 return outPath, nil
604}
605
606func lastUserText(msgs []provider.Message) string {
607 for i := len(msgs) - 1; i >= 0; i-- {
608 if msgs[i].Role != provider.RoleUser {
609 continue
610 }
611 if text := strings.TrimSpace(firstTextFromMessage(msgs[i])); text != "" {
612 return text
613 }
614 }
615 return ""
616}
617
618// TreeNode is one entry in the branch tree returned by
619// BuildSessionTree. Children are populated by linking on Parent ID.
620type TreeNode struct {
621 Summary SessionSummary
622 Meta SessionMeta
623 Children []*TreeNode
624}
625
626// BuildSessionTree loads every session in the cwd dir and returns
627// the forest rooted at parentless sessions, with each non-root
628// session placed under its parent. Used by /session tree to render
629// the branch hierarchy.
630func BuildSessionTree(root, cwd string) []*TreeNode {
631 dir := SessionsDir(root, cwd)
632 entries, err := os.ReadDir(dir)
633 if err != nil {
634 return nil
635 }
636 nodes := make(map[string]*TreeNode)
637 order := []string{}
638 for _, e := range entries {
639 if e.IsDir() || !strings.HasSuffix(e.Name(), ".jsonl") {
640 continue
641 }
642 path := filepath.Join(dir, e.Name())
643 summary := describeSession(path)
644 meta, _ := readSessionMeta(path)
645 if meta.ID == "" {
646 continue
647 }
648 nodes[meta.ID] = &TreeNode{Summary: summary, Meta: meta}
649 order = append(order, meta.ID)
650 }
651 return linkSessionTreeNodes(nodes, order)
652}
653
654// BuildSessionTreeStrict is the complete-read counterpart to the permissive
655// forest builder. It validates every session file before linking any node, so
656// callers that need a complete forest cannot silently omit malformed members.
657func BuildSessionTreeStrict(root, cwd string) ([]*TreeNode, error) {
658 dir := SessionsDir(root, cwd)
659 entries, err := os.ReadDir(dir)
660 if err != nil {
661 if errors.Is(err, os.ErrNotExist) {
662 return nil, nil
663 }
664 return nil, fmt.Errorf("build session tree: read directory: %w", err)
665 }
666 nodes := make(map[string]*TreeNode)
667 order := make([]string, 0, len(entries))
668 for _, e := range entries {
669 if e.IsDir() || !strings.HasSuffix(e.Name(), ".jsonl") {
670 continue
671 }
672 path := filepath.Join(dir, e.Name())
673 snapshot, err := ReadSessionSnapshot(path)
674 if err != nil {
675 return nil, fmt.Errorf("build session tree: read %q: %w", path, err)
676 }
677 if snapshot.Meta.ID == "" {
678 return nil, fmt.Errorf("build session tree: %q has no session id", path)
679 }
680 summary := SessionSummary{
681 Path: path,
682 Started: snapshot.Meta.Started,
683 Model: snapshot.Meta.Model,
684 Provider: snapshot.Meta.Provider,
685 MessageCount: len(snapshot.Messages),
686 FirstUserText: firstUserTextFromMessages(snapshot.Messages),
687 Title: snapshot.Meta.Title,
688 }
689 if len(snapshot.UsageCheckpoints) > 0 {
690 summary.TotalCost = snapshot.UsageCheckpoints[len(snapshot.UsageCheckpoints)-1].Cumulative.CostUSD
691 }
692 if _, exists := nodes[snapshot.Meta.ID]; exists {
693 return nil, fmt.Errorf("build session tree: duplicate session id %q", snapshot.Meta.ID)
694 }
695 nodes[snapshot.Meta.ID] = &TreeNode{Summary: summary, Meta: snapshot.Meta}
696 order = append(order, snapshot.Meta.ID)
697 }
698 return linkSessionTreeNodes(nodes, order), nil
699}
700
701// BuildSessionTreeFamilyStrict locates the current session using lightweight
702// metadata headers, then strictly validates only that root and its descendants.
703// A corrupt unrelated root in the same cwd bucket must not hide an otherwise
704// readable current family, while a corrupt member of the selected family still
705// fails the whole preflight.
706func BuildSessionTreeFamilyStrict(root, cwd, currentPath string) ([]*TreeNode, error) {
707 return BuildSessionTreeFamilyStrictContext(context.Background(), root, cwd, currentPath)
708}
709
710// BuildSessionTreeFamilyStrictContext is the cancellation-aware counterpart
711// to BuildSessionTreeFamilyStrict. It performs all filesystem reads on behalf
712// of callers that must remain responsive while a family is being discovered.
713func BuildSessionTreeFamilyStrictContext(ctx context.Context, root, cwd, currentPath string) ([]*TreeNode, error) {
714 roots, err := buildSessionTreeFamilyContext(ctx, root, cwd, currentPath)
715 if err != nil || len(roots) == 0 {
716 return roots, err
717 }
718 var validate func(*TreeNode) error
719 validate = func(node *TreeNode) error {
720 if err := contextErr(ctx); err != nil {
721 return err
722 }
723 snapshot, err := readSessionSnapshot(ctx, node.Summary.Path)
724 if err != nil {
725 return fmt.Errorf("build session family: read %q: %w", node.Summary.Path, err)
726 }
727 if snapshot.Meta.ID != node.Meta.ID {
728 return fmt.Errorf("build session family: session id changed in %q", node.Summary.Path)
729 }
730 node.Meta = snapshot.Meta
731 node.Summary = SessionSummary{
732 Path: node.Summary.Path,
733 Started: snapshot.Meta.Started,
734 Model: snapshot.Meta.Model,
735 Provider: snapshot.Meta.Provider,
736 MessageCount: len(snapshot.Messages),
737 FirstUserText: firstUserTextFromMessages(snapshot.Messages),
738 Title: snapshot.Meta.Title,
739 }
740 if len(snapshot.UsageCheckpoints) > 0 {
741 node.Summary.TotalCost = snapshot.UsageCheckpoints[len(snapshot.UsageCheckpoints)-1].Cumulative.CostUSD
742 }
743 for _, child := range node.Children {
744 if err := validate(child); err != nil {
745 return err
746 }
747 }
748 return nil
749 }
750 if err := validate(roots[0]); err != nil {
751 return nil, err
752 }
753 return roots, nil
754}
755
756// BuildSessionTreeFamilyContext discovers the current family from metadata
757// headers. Consumers that read every member themselves can start that work in
758// their preferred order without a redundant whole-family snapshot pass.
759func BuildSessionTreeFamilyContext(ctx context.Context, root, cwd, currentPath string) ([]*TreeNode, error) {
760 return buildSessionTreeFamilyContext(ctx, root, cwd, currentPath)
761}
762
763func buildSessionTreeFamilyContext(ctx context.Context, root, cwd, currentPath string) ([]*TreeNode, error) {
764 if err := contextErr(ctx); err != nil {
765 return nil, err
766 }
767 if currentPath == "" {
768 return nil, errors.New("build session family: current path is empty")
769 }
770 dir := SessionsDir(root, cwd)
771 entries, err := os.ReadDir(dir)
772 if err != nil {
773 if errors.Is(err, os.ErrNotExist) {
774 return nil, nil
775 }
776 return nil, fmt.Errorf("build session family: read directory: %w", err)
777 }
778 cleanCurrent := filepath.Clean(currentPath)
779 nodes := make(map[string]*TreeNode)
780 order := make([]string, 0, len(entries))
781 for _, entry := range entries {
782 if err := contextErr(ctx); err != nil {
783 return nil, err
784 }
785 if entry.IsDir() || !strings.HasSuffix(entry.Name(), ".jsonl") {
786 continue
787 }
788 path := filepath.Join(dir, entry.Name())
789 meta, err := readSessionMetaHeader(path)
790 if err != nil {
791 if filepath.Clean(path) == cleanCurrent {
792 return nil, fmt.Errorf("build session family: read current metadata %q: %w", path, err)
793 }
794 // A file whose header is unreadable cannot be associated with the
795 // selected family. Valid descendants are linked below and fully
796 // preflighted; unrelated corrupt roots stay out of this family.
797 continue
798 }
799 if _, exists := nodes[meta.ID]; exists {
800 return nil, fmt.Errorf("build session family: duplicate session id %q", meta.ID)
801 }
802 nodes[meta.ID] = &TreeNode{
803 Summary: SessionSummary{Path: path, Started: meta.Started, Model: meta.Model, Provider: meta.Provider},
804 Meta: meta,
805 }
806 order = append(order, meta.ID)
807 }
808 roots := linkSessionTreeNodes(nodes, order)
809 var familyRoot *TreeNode
810 for _, candidate := range roots {
811 if treeNodeContainsPath(candidate, cleanCurrent) {
812 familyRoot = candidate
813 break
814 }
815 }
816 if familyRoot == nil {
817 return nil, fmt.Errorf("build session family: current path %q is not in the session forest", currentPath)
818 }
819 return []*TreeNode{familyRoot}, nil
820}
821
822func readSessionMetaHeader(path string) (SessionMeta, error) {
823 f, err := os.Open(path)
824 if err != nil {
825 return SessionMeta{}, err
826 }
827 defer f.Close()
828 line, err := bufio.NewReader(f).ReadBytes('\n')
829 if err != nil && len(line) == 0 {
830 return SessionMeta{}, err
831 }
832 line = bytes.TrimSpace(line)
833 var row sessionLine
834 if err := json.Unmarshal(line, &row); err != nil {
835 return SessionMeta{}, err
836 }
837 if row.Type != "meta" || row.Meta == nil || row.Meta.ID == "" {
838 return SessionMeta{}, errors.New("first row is not a valid meta row")
839 }
840 return *row.Meta, nil
841}
842
843func treeNodeContainsPath(node *TreeNode, path string) bool {
844 if node == nil {
845 return false
846 }
847 if filepath.Clean(node.Summary.Path) == filepath.Clean(path) {
848 return true
849 }
850 for _, child := range node.Children {
851 if treeNodeContainsPath(child, path) {
852 return true
853 }
854 }
855 return false
856}
857
858func linkSessionTreeNodes(nodes map[string]*TreeNode, order []string) []*TreeNode {
859 var roots []*TreeNode
860 for _, id := range order {
861 n := nodes[id]
862 if n.Meta.Parent == "" {
863 roots = append(roots, n)
864 continue
865 }
866 if parent, ok := nodes[n.Meta.Parent]; ok {
867 parent.Children = append(parent.Children, n)
868 } else {
869 // Parent file missing (was manually deleted). Treat as a root so it
870 // still shows up in the tree.
871 roots = append(roots, n)
872 }
873 }
874 return roots
875}
876
877// scanSessionMeta reads JSONL rows without hydrating transcript content and
878// returns the latest valid metadata row. Listing and ID lookup only need this
879// small projection; full snapshot validation remains the responsibility of
880// resume, export, branching, and tree preflight callers.
881func scanSessionMeta(path string) (meta SessionMeta, err error) {
882 return scanSessionMetaContext(context.Background(), path)
883}
884
885func scanSessionMetaContext(ctx context.Context, path string) (meta SessionMeta, err error) {
886 if err := contextErr(ctx); err != nil {
887 return SessionMeta{}, err
888 }
889 f, err := os.Open(path)
890 if err != nil {
891 return SessionMeta{}, err
892 }
893 defer f.Close()
894
895 var sawMeta bool
896 err = forEachStrictJSONLLineContext(ctx, f, func(line []byte, lineNo int) error {
897 var head sessionLineHead
898 if err := json.Unmarshal(line, &head); err != nil {
899 return fmt.Errorf("line %d: invalid JSON: %w", lineNo, err)
900 }
901 if head.Type == "" {
902 return fmt.Errorf("line %d: missing row type", lineNo)
903 }
904 if !sawMeta && head.Type != "meta" {
905 return fmt.Errorf("line %d: first row is not meta", lineNo)
906 }
907 switch head.Type {
908 case "meta":
909 var row struct {
910 Meta *SessionMeta `json:"meta"`
911 }
912 if err := json.Unmarshal(line, &row); err != nil {
913 return fmt.Errorf("line %d: invalid meta row: %w", lineNo, err)
914 }
915 if row.Meta == nil || row.Meta.ID == "" {
916 return fmt.Errorf("line %d: meta row has no session id", lineNo)
917 }
918 meta = *row.Meta
919 sawMeta = true
920 case "message", "compaction", "usage", "rename", "extension_state":
921 // These rows are intentionally not hydrated here.
922 default:
923 return fmt.Errorf("line %d: unknown row type %q", lineNo, head.Type)
924 }
925 return nil
926 })
927 if err != nil {
928 return SessionMeta{}, fmt.Errorf("session metadata %q: %w", path, err)
929 }
930 if !sawMeta {
931 return SessionMeta{}, fmt.Errorf("session metadata %q: file is empty", path)
932 }
933 return meta, nil
934}
935
936// readSessionMeta returns the latest validated metadata for path without
937// reconstructing its transcript. Full snapshot validation is performed by
938// callers that need messages rather than listing metadata.
939func readSessionMeta(path string) (SessionMeta, error) {
940 return scanSessionMeta(path)
941}
942
943// FindSessionByID looks up a session file in root/cwd whose meta id
944// matches. Used by /session tree when the user picks an entry. O(n)
945// over the files in the dir; the list is small in practice.
946func FindSessionByID(root, cwd, id string) string {
947 dir := SessionsDir(root, cwd)
948 entries, err := os.ReadDir(dir)
949 if err != nil {
950 return ""
951 }
952 for _, e := range entries {
953 if e.IsDir() || !strings.HasSuffix(e.Name(), ".jsonl") {
954 continue
955 }
956 path := filepath.Join(dir, e.Name())
957 meta, err := scanSessionMeta(path)
958 if err != nil {
959 continue
960 }
961 if meta.ID == id {
962 return path
963 }
964 }
965 return ""
966}
967
968// FindManagedSessionByID looks up a session UUID across zut's managed
969// session stores, independent of cwd. A nil error and empty path mean no
970// matching session was found. Read, storage, metadata, and duplicate-ID
971// failures are returned to the caller instead of being reported as a miss.
972func FindManagedSessionByID(ctx context.Context, root, id string) (string, error) {
973 if strings.TrimSpace(root) == "" {
974 return "", errors.New("find managed session: root is empty")
975 }
976 if strings.TrimSpace(id) == "" {
977 return "", errors.New("find managed session: id is empty")
978 }
979
980 stores := []string{root}
981 agentsDir := filepath.Join(root, "sessions", "agents")
982 agents, err := os.ReadDir(agentsDir)
983 if err != nil && !errors.Is(err, os.ErrNotExist) {
984 return "", fmt.Errorf("find managed session: read agent stores: %w", err)
985 }
986 if err == nil {
987 for _, entry := range agents {
988 if entry.IsDir() {
989 stores = append(stores, filepath.Join(agentsDir, entry.Name()))
990 }
991 }
992 }
993
994 var matches []string
995 for _, store := range stores {
996 if err := contextErr(ctx); err != nil {
997 return "", err
998 }
999 if err := collectManagedSessionMatches(ctx, store, id, &matches); err != nil {
1000 return "", err
1001 }
1002 }
1003 if err := contextErr(ctx); err != nil {
1004 return "", err
1005 }
1006 if len(matches) == 0 {
1007 return "", nil
1008 }
1009 if len(matches) > 1 {
1010 return "", fmt.Errorf("find managed session: UUID %q is ambiguous", id)
1011 }
1012 return matches[0], nil
1013}
1014
1015func collectManagedSessionMatches(ctx context.Context, root, id string, matches *[]string) error {
1016 if err := contextErr(ctx); err != nil {
1017 return err
1018 }
1019 dir := filepath.Join(root, "sessions")
1020 entries, err := os.ReadDir(dir)
1021 if errors.Is(err, os.ErrNotExist) {
1022 return nil
1023 }
1024 if err != nil {
1025 return fmt.Errorf("find managed session: read %q: %w", dir, err)
1026 }
1027 for _, bucket := range entries {
1028 if err := contextErr(ctx); err != nil {
1029 return err
1030 }
1031 if !bucket.IsDir() || bucket.Name() == "agents" || !isSessionBucketName(bucket.Name()) {
1032 continue
1033 }
1034 bucketPath := filepath.Join(dir, bucket.Name())
1035 files, err := os.ReadDir(bucketPath)
1036 if err != nil {
1037 return fmt.Errorf("find managed session: read %q: %w", bucketPath, err)
1038 }
1039 for _, file := range files {
1040 if err := contextErr(ctx); err != nil {
1041 return err
1042 }
1043 if file.IsDir() || !strings.HasSuffix(file.Name(), ".jsonl") {
1044 continue
1045 }
1046 path := filepath.Join(bucketPath, file.Name())
1047 meta, err := scanSessionMetaContext(ctx, path)
1048 if err != nil {
1049 return fmt.Errorf("find managed session: read metadata %q: %w", path, err)
1050 }
1051 if meta.ID == id {
1052 *matches = append(*matches, path)
1053 }
1054 }
1055 }
1056 return nil
1057}
1058
1059func isSessionBucketName(name string) bool {
1060 if len(name) != 16 {
1061 return false
1062 }
1063 for _, r := range name {
1064 if (r < '0' || r > '9') && (r < 'a' || r > 'f') {
1065 return false
1066 }
1067 }
1068 return true
1069}
1070
1071// firstUserPrompt scans forward from the current source position
1072// looking for the first user-role message and returns its text.
1073// Used to build a humane export filename. Uses Reader instead of
1074// Scanner so a very large JSONL row before the first user prompt
1075// cannot trip Scanner's token limit.
1076func firstUserPrompt(src io.Reader) (string, error) {
1077 r := bufio.NewReader(src)
1078 for {
1079 lineBytes, err := r.ReadBytes('\n')
1080 if len(lineBytes) > 0 {
1081 lineBytes = bytes.TrimRight(lineBytes, "\r\n")
1082 var line sessionLine
1083 if err := json.Unmarshal(lineBytes, &line); err == nil {
1084 if line.Type == "message" && line.Message != nil && line.Message.Role == "user" {
1085 b, _ := json.Marshal(line.Message)
1086 var m struct {
1087 Content []struct {
1088 Text string `json:"text"`
1089 } `json:"content"`
1090 }
1091 _ = json.Unmarshal(b, &m)
1092 for _, c := range m.Content {
1093 if c.Text != "" {
1094 return c.Text, nil
1095 }
1096 }
1097 }
1098 }
1099 }
1100 if err == io.EOF {
1101 return "", nil
1102 }
1103 if err != nil {
1104 return "", err
1105 }
1106 }
1107}
1108
1109// filenameFor builds a descriptive .zutsession filename from the
1110// session's start time and, when available, an excerpt of the
1111// first user prompt.
1112func filenameFor(started time.Time, id, firstPrompt string) string {
1113 base := started.UTC().Format("20060102-150405")
1114 if id != "" && len(id) >= 8 {
1115 base += "-" + id[:8]
1116 }
1117 slug := slugify(firstPrompt, 40)
1118 if slug != "" {
1119 base += "-" + slug
1120 }
1121 return base + PortableExt
1122}
1123
1124// slugify lowercases, strips punctuation, collapses whitespace to
1125// hyphens, and truncates to max runes so it's safe as a filename.
1126func slugify(s string, max int) string {
1127 s = strings.TrimSpace(strings.ToLower(s))
1128 if s == "" {
1129 return ""
1130 }
1131 var out strings.Builder
1132 prevDash := false
1133 for _, r := range s {
1134 switch {
1135 case r >= 'a' && r <= 'z', r >= '0' && r <= '9':
1136 out.WriteRune(r)
1137 prevDash = false
1138 default:
1139 if !prevDash && out.Len() > 0 {
1140 out.WriteByte('-')
1141 prevDash = true
1142 }
1143 }
1144 if out.Len() >= max {
1145 break
1146 }
1147 }
1148 return strings.TrimRight(out.String(), "-")
1149}