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 if goal.TokenBudget != nil {
464 budget := *goal.TokenBudget
465 clone.TokenBudget = &budget
466 }
467 return &clone
468}
469
470func cloneGoalHistory(history []SessionGoal) []SessionGoal {
471 if len(history) == 0 {
472 return nil
473 }
474 clone := make([]SessionGoal, len(history))
475 for index := range history {
476 clone[index] = *cloneSessionGoal(&history[index])
477 }
478 return clone
479}
480
481func goalHistoryAtBranch(parent SessionMeta, messages []provider.Message, limit int) []SessionGoal {
482 if limit != len(messages) {
483 return nil
484 }
485 return cloneGoalHistory(parent.GoalHistory)
486}
487
488func 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) {
489 dir := SessionsDir(root, cwd)
490 if err := os.MkdirAll(dir, 0o755); err != nil {
491 return "", err
492 }
493 newID := uuid.NewString()
494 name := fmt.Sprintf("%s-%s.jsonl", time.Now().UTC().Format("20060102-150405"), newID[:8])
495 outPath := filepath.Join(dir, name)
496 // Build in a same-directory temporary file. Rename is atomic only when
497 // the temporary and final paths share a directory; closing the file first
498 // also ensures no buffered writer or descriptor can expose a partial branch.
499 dst, err := os.CreateTemp(dir, ".zut-branch-*.tmp")
500 if err != nil {
501 return "", fmt.Errorf("branch: create temp: %w", err)
502 }
503 tmpPath := dst.Name()
504 if err := dst.Chmod(0o644); err != nil {
505 _ = dst.Close()
506 _ = os.Remove(tmpPath)
507 return "", fmt.Errorf("branch: chmod temp: %w", err)
508 }
509 committed := false
510 defer func() {
511 _ = dst.Close()
512 if !committed {
513 _ = os.Remove(tmpPath)
514 _ = os.Remove(outPath)
515 }
516 }()
517 bw := bufio.NewWriter(dst)
518
519 branchMeta := SessionMeta{
520 ID: newID,
521 CWD: cwd,
522 Model: parent.Model,
523 Provider: parent.Provider,
524 Started: time.Now().UTC(),
525 Version: version,
526 Parent: parent.ID,
527 ForkPoint: limit,
528 HideFromSessions: hideFromSessions,
529 CompactHandoff: append(json.RawMessage(nil), compactHandoff...),
530 Mission: missionAtBranch(parent, messages, limit),
531 Goal: cloneSessionGoal(goal),
532 GoalHistory: goalHistoryAtBranch(parent, messages, limit),
533 }
534 metaLine, err := json.Marshal(sessionLine{Type: "meta", Meta: &branchMeta})
535 if err != nil {
536 return "", fmt.Errorf("branch: marshal meta: %w", err)
537 }
538 if _, err := bw.Write(metaLine); err != nil {
539 return "", err
540 }
541 if err := bw.WriteByte('\n'); err != nil {
542 return "", err
543 }
544
545 for idx := 0; idx < limit; idx++ {
546 msg := messages[idx]
547 line, err := json.Marshal(sessionLine{Type: "message", Message: &msg})
548 if err != nil {
549 return "", fmt.Errorf("branch: marshal message %d: %w", idx, err)
550 }
551 if _, err := bw.Write(line); err != nil {
552 return "", err
553 }
554 if err := bw.WriteByte('\n'); err != nil {
555 return "", err
556 }
557 }
558
559 // Extension snapshots are branch state, not provider-visible transcript
560 // content. Write the latest snapshot that existed at the fork point so a
561 // child branch starts from the same extension state as its copied prefix.
562 extensionNames := make([]string, 0, len(extensionState))
563 for name := range extensionState {
564 extensionNames = append(extensionNames, name)
565 }
566 sort.Strings(extensionNames)
567 for _, name := range extensionNames {
568 line, err := json.Marshal(sessionLine{Type: "extension_state", Extension: name, State: extensionState[name]})
569 if err != nil {
570 return "", fmt.Errorf("branch: marshal extension state: %w", err)
571 }
572 if _, err := bw.Write(line); err != nil {
573 return "", fmt.Errorf("branch: write extension state: %w", err)
574 }
575 if err := bw.WriteByte('\n'); err != nil {
576 return "", fmt.Errorf("branch: terminate extension state row: %w", err)
577 }
578 }
579 // Preserve every cumulative checkpoint that belongs to this prefix. The
580 // final two rows are needed to reconstruct LastTurnUsage as a delta.
581 for _, checkpoint := range checkpoints {
582 if checkpoint.MessageCount > limit {
583 continue
584 }
585 usageLine, err := json.Marshal(sessionLine{
586 Type: "usage",
587 Usage: &checkpoint.Cumulative,
588 Cumulative: &checkpoint.Cumulative,
589 })
590 if err != nil {
591 return "", fmt.Errorf("branch: marshal usage: %w", err)
592 }
593 if _, err := bw.Write(usageLine); err != nil {
594 return "", err
595 }
596 if err := bw.WriteByte('\n'); err != nil {
597 return "", err
598 }
599 }
600
601 if err := bw.Flush(); err != nil {
602 return "", err
603 }
604 if err := dst.Sync(); err != nil {
605 return "", fmt.Errorf("branch: sync temp: %w", err)
606 }
607 if err := dst.Close(); err != nil {
608 return "", fmt.Errorf("branch: close temp: %w", err)
609 }
610 if err := os.Rename(tmpPath, outPath); err != nil {
611 return "", fmt.Errorf("branch: commit: %w", err)
612 }
613 committed = true
614 return outPath, nil
615}
616
617func lastUserText(msgs []provider.Message) string {
618 for i := len(msgs) - 1; i >= 0; i-- {
619 if msgs[i].Role != provider.RoleUser {
620 continue
621 }
622 if text := strings.TrimSpace(firstTextFromMessage(msgs[i])); text != "" {
623 return text
624 }
625 }
626 return ""
627}
628
629// TreeNode is one entry in the branch tree returned by
630// BuildSessionTree. Children are populated by linking on Parent ID.
631type TreeNode struct {
632 Summary SessionSummary
633 Meta SessionMeta
634 Children []*TreeNode
635}
636
637// BuildSessionTree loads every session in the cwd dir and returns
638// the forest rooted at parentless sessions, with each non-root
639// session placed under its parent. Used by /session tree to render
640// the branch hierarchy.
641func BuildSessionTree(root, cwd string) []*TreeNode {
642 dir := SessionsDir(root, cwd)
643 entries, err := os.ReadDir(dir)
644 if err != nil {
645 return nil
646 }
647 nodes := make(map[string]*TreeNode)
648 order := []string{}
649 for _, e := range entries {
650 if e.IsDir() || !strings.HasSuffix(e.Name(), ".jsonl") {
651 continue
652 }
653 path := filepath.Join(dir, e.Name())
654 summary := describeSession(path)
655 meta, _ := readSessionMeta(path)
656 if meta.ID == "" {
657 continue
658 }
659 nodes[meta.ID] = &TreeNode{Summary: summary, Meta: meta}
660 order = append(order, meta.ID)
661 }
662 return linkSessionTreeNodes(nodes, order)
663}
664
665// BuildSessionTreeStrict is the complete-read counterpart to the permissive
666// forest builder. It validates every session file before linking any node, so
667// callers that need a complete forest cannot silently omit malformed members.
668func BuildSessionTreeStrict(root, cwd string) ([]*TreeNode, error) {
669 dir := SessionsDir(root, cwd)
670 entries, err := os.ReadDir(dir)
671 if err != nil {
672 if errors.Is(err, os.ErrNotExist) {
673 return nil, nil
674 }
675 return nil, fmt.Errorf("build session tree: read directory: %w", err)
676 }
677 nodes := make(map[string]*TreeNode)
678 order := make([]string, 0, len(entries))
679 for _, e := range entries {
680 if e.IsDir() || !strings.HasSuffix(e.Name(), ".jsonl") {
681 continue
682 }
683 path := filepath.Join(dir, e.Name())
684 snapshot, err := ReadSessionSnapshot(path)
685 if err != nil {
686 return nil, fmt.Errorf("build session tree: read %q: %w", path, err)
687 }
688 if snapshot.Meta.ID == "" {
689 return nil, fmt.Errorf("build session tree: %q has no session id", path)
690 }
691 summary := SessionSummary{
692 Path: path,
693 Started: snapshot.Meta.Started,
694 Model: snapshot.Meta.Model,
695 Provider: snapshot.Meta.Provider,
696 MessageCount: len(snapshot.Messages),
697 FirstUserText: firstUserTextFromMessages(snapshot.Messages),
698 Title: snapshot.Meta.Title,
699 }
700 if len(snapshot.UsageCheckpoints) > 0 {
701 summary.TotalCost = snapshot.UsageCheckpoints[len(snapshot.UsageCheckpoints)-1].Cumulative.CostUSD
702 }
703 if _, exists := nodes[snapshot.Meta.ID]; exists {
704 return nil, fmt.Errorf("build session tree: duplicate session id %q", snapshot.Meta.ID)
705 }
706 nodes[snapshot.Meta.ID] = &TreeNode{Summary: summary, Meta: snapshot.Meta}
707 order = append(order, snapshot.Meta.ID)
708 }
709 return linkSessionTreeNodes(nodes, order), nil
710}
711
712// BuildSessionTreeFamilyStrict locates the current session using lightweight
713// metadata headers, then strictly validates only that root and its descendants.
714// A corrupt unrelated root in the same cwd bucket must not hide an otherwise
715// readable current family, while a corrupt member of the selected family still
716// fails the whole preflight.
717func BuildSessionTreeFamilyStrict(root, cwd, currentPath string) ([]*TreeNode, error) {
718 return BuildSessionTreeFamilyStrictContext(context.Background(), root, cwd, currentPath)
719}
720
721// BuildSessionTreeFamilyStrictContext is the cancellation-aware counterpart
722// to BuildSessionTreeFamilyStrict. It performs all filesystem reads on behalf
723// of callers that must remain responsive while a family is being discovered.
724func BuildSessionTreeFamilyStrictContext(ctx context.Context, root, cwd, currentPath string) ([]*TreeNode, error) {
725 roots, err := buildSessionTreeFamilyContext(ctx, root, cwd, currentPath)
726 if err != nil || len(roots) == 0 {
727 return roots, err
728 }
729 var validate func(*TreeNode) error
730 validate = func(node *TreeNode) error {
731 if err := contextErr(ctx); err != nil {
732 return err
733 }
734 snapshot, err := readSessionSnapshot(ctx, node.Summary.Path)
735 if err != nil {
736 return fmt.Errorf("build session family: read %q: %w", node.Summary.Path, err)
737 }
738 if snapshot.Meta.ID != node.Meta.ID {
739 return fmt.Errorf("build session family: session id changed in %q", node.Summary.Path)
740 }
741 node.Meta = snapshot.Meta
742 node.Summary = SessionSummary{
743 Path: node.Summary.Path,
744 Started: snapshot.Meta.Started,
745 Model: snapshot.Meta.Model,
746 Provider: snapshot.Meta.Provider,
747 MessageCount: len(snapshot.Messages),
748 FirstUserText: firstUserTextFromMessages(snapshot.Messages),
749 Title: snapshot.Meta.Title,
750 }
751 if len(snapshot.UsageCheckpoints) > 0 {
752 node.Summary.TotalCost = snapshot.UsageCheckpoints[len(snapshot.UsageCheckpoints)-1].Cumulative.CostUSD
753 }
754 for _, child := range node.Children {
755 if err := validate(child); err != nil {
756 return err
757 }
758 }
759 return nil
760 }
761 if err := validate(roots[0]); err != nil {
762 return nil, err
763 }
764 return roots, nil
765}
766
767// BuildSessionTreeFamilyContext discovers the current family from metadata
768// headers. Consumers that read every member themselves can start that work in
769// their preferred order without a redundant whole-family snapshot pass.
770func BuildSessionTreeFamilyContext(ctx context.Context, root, cwd, currentPath string) ([]*TreeNode, error) {
771 return buildSessionTreeFamilyContext(ctx, root, cwd, currentPath)
772}
773
774func buildSessionTreeFamilyContext(ctx context.Context, root, cwd, currentPath string) ([]*TreeNode, error) {
775 if err := contextErr(ctx); err != nil {
776 return nil, err
777 }
778 if currentPath == "" {
779 return nil, errors.New("build session family: current path is empty")
780 }
781 dir := SessionsDir(root, cwd)
782 entries, err := os.ReadDir(dir)
783 if err != nil {
784 if errors.Is(err, os.ErrNotExist) {
785 return nil, nil
786 }
787 return nil, fmt.Errorf("build session family: read directory: %w", err)
788 }
789 cleanCurrent := filepath.Clean(currentPath)
790 nodes := make(map[string]*TreeNode)
791 order := make([]string, 0, len(entries))
792 for _, entry := range entries {
793 if err := contextErr(ctx); err != nil {
794 return nil, err
795 }
796 if entry.IsDir() || !strings.HasSuffix(entry.Name(), ".jsonl") {
797 continue
798 }
799 path := filepath.Join(dir, entry.Name())
800 meta, err := readSessionMetaHeader(path)
801 if err != nil {
802 if filepath.Clean(path) == cleanCurrent {
803 return nil, fmt.Errorf("build session family: read current metadata %q: %w", path, err)
804 }
805 // A file whose header is unreadable cannot be associated with the
806 // selected family. Valid descendants are linked below and fully
807 // preflighted; unrelated corrupt roots stay out of this family.
808 continue
809 }
810 if _, exists := nodes[meta.ID]; exists {
811 return nil, fmt.Errorf("build session family: duplicate session id %q", meta.ID)
812 }
813 nodes[meta.ID] = &TreeNode{
814 Summary: SessionSummary{Path: path, Started: meta.Started, Model: meta.Model, Provider: meta.Provider},
815 Meta: meta,
816 }
817 order = append(order, meta.ID)
818 }
819 roots := linkSessionTreeNodes(nodes, order)
820 var familyRoot *TreeNode
821 for _, candidate := range roots {
822 if treeNodeContainsPath(candidate, cleanCurrent) {
823 familyRoot = candidate
824 break
825 }
826 }
827 if familyRoot == nil {
828 return nil, fmt.Errorf("build session family: current path %q is not in the session forest", currentPath)
829 }
830 return []*TreeNode{familyRoot}, nil
831}
832
833func readSessionMetaHeader(path string) (SessionMeta, error) {
834 f, err := os.Open(path)
835 if err != nil {
836 return SessionMeta{}, err
837 }
838 defer f.Close()
839 line, err := bufio.NewReader(f).ReadBytes('\n')
840 if err != nil && len(line) == 0 {
841 return SessionMeta{}, err
842 }
843 line = bytes.TrimSpace(line)
844 var row sessionLine
845 if err := json.Unmarshal(line, &row); err != nil {
846 return SessionMeta{}, err
847 }
848 if row.Type != "meta" || row.Meta == nil || row.Meta.ID == "" {
849 return SessionMeta{}, errors.New("first row is not a valid meta row")
850 }
851 return *row.Meta, nil
852}
853
854func treeNodeContainsPath(node *TreeNode, path string) bool {
855 if node == nil {
856 return false
857 }
858 if filepath.Clean(node.Summary.Path) == filepath.Clean(path) {
859 return true
860 }
861 for _, child := range node.Children {
862 if treeNodeContainsPath(child, path) {
863 return true
864 }
865 }
866 return false
867}
868
869func linkSessionTreeNodes(nodes map[string]*TreeNode, order []string) []*TreeNode {
870 var roots []*TreeNode
871 for _, id := range order {
872 n := nodes[id]
873 if n.Meta.Parent == "" {
874 roots = append(roots, n)
875 continue
876 }
877 if parent, ok := nodes[n.Meta.Parent]; ok {
878 parent.Children = append(parent.Children, n)
879 } else {
880 // Parent file missing (was manually deleted). Treat as a root so it
881 // still shows up in the tree.
882 roots = append(roots, n)
883 }
884 }
885 return roots
886}
887
888// scanSessionMeta reads JSONL rows without hydrating transcript content and
889// returns the latest valid metadata row. Listing and ID lookup only need this
890// small projection; full snapshot validation remains the responsibility of
891// resume, export, branching, and tree preflight callers.
892func scanSessionMeta(path string) (meta SessionMeta, err error) {
893 return scanSessionMetaContext(context.Background(), path)
894}
895
896func scanSessionMetaContext(ctx context.Context, path string) (meta SessionMeta, err error) {
897 if err := contextErr(ctx); err != nil {
898 return SessionMeta{}, err
899 }
900 f, err := os.Open(path)
901 if err != nil {
902 return SessionMeta{}, err
903 }
904 defer f.Close()
905
906 var sawMeta bool
907 err = forEachStrictJSONLLineContext(ctx, f, func(line []byte, lineNo int) error {
908 var head sessionLineHead
909 if err := json.Unmarshal(line, &head); err != nil {
910 return fmt.Errorf("line %d: invalid JSON: %w", lineNo, err)
911 }
912 if head.Type == "" {
913 return fmt.Errorf("line %d: missing row type", lineNo)
914 }
915 if !sawMeta && head.Type != "meta" {
916 return fmt.Errorf("line %d: first row is not meta", lineNo)
917 }
918 switch head.Type {
919 case "meta":
920 var row struct {
921 Meta *SessionMeta `json:"meta"`
922 }
923 if err := json.Unmarshal(line, &row); err != nil {
924 return fmt.Errorf("line %d: invalid meta row: %w", lineNo, err)
925 }
926 if row.Meta == nil || row.Meta.ID == "" {
927 return fmt.Errorf("line %d: meta row has no session id", lineNo)
928 }
929 meta = *row.Meta
930 sawMeta = true
931 case "message", "compaction", "usage", "rename", "extension_state":
932 // These rows are intentionally not hydrated here.
933 default:
934 return fmt.Errorf("line %d: unknown row type %q", lineNo, head.Type)
935 }
936 return nil
937 })
938 if err != nil {
939 return SessionMeta{}, fmt.Errorf("session metadata %q: %w", path, err)
940 }
941 if !sawMeta {
942 return SessionMeta{}, fmt.Errorf("session metadata %q: file is empty", path)
943 }
944 return meta, nil
945}
946
947// readSessionMeta returns the latest validated metadata for path without
948// reconstructing its transcript. Full snapshot validation is performed by
949// callers that need messages rather than listing metadata.
950func readSessionMeta(path string) (SessionMeta, error) {
951 return scanSessionMeta(path)
952}
953
954// FindSessionByID looks up a session file in root/cwd whose meta id
955// matches. Used by /session tree when the user picks an entry. O(n)
956// over the files in the dir; the list is small in practice.
957func FindSessionByID(root, cwd, id string) string {
958 dir := SessionsDir(root, cwd)
959 entries, err := os.ReadDir(dir)
960 if err != nil {
961 return ""
962 }
963 for _, e := range entries {
964 if e.IsDir() || !strings.HasSuffix(e.Name(), ".jsonl") {
965 continue
966 }
967 path := filepath.Join(dir, e.Name())
968 meta, err := scanSessionMeta(path)
969 if err != nil {
970 continue
971 }
972 if meta.ID == id {
973 return path
974 }
975 }
976 return ""
977}
978
979// FindManagedSessionByID looks up a session UUID across zut's managed
980// session stores, independent of cwd. A nil error and empty path mean no
981// matching session was found. Read, storage, metadata, and duplicate-ID
982// failures are returned to the caller instead of being reported as a miss.
983func FindManagedSessionByID(ctx context.Context, root, id string) (string, error) {
984 if strings.TrimSpace(root) == "" {
985 return "", errors.New("find managed session: root is empty")
986 }
987 if strings.TrimSpace(id) == "" {
988 return "", errors.New("find managed session: id is empty")
989 }
990
991 stores := []string{root}
992 agentsDir := filepath.Join(root, "sessions", "agents")
993 agents, err := os.ReadDir(agentsDir)
994 if err != nil && !errors.Is(err, os.ErrNotExist) {
995 return "", fmt.Errorf("find managed session: read agent stores: %w", err)
996 }
997 if err == nil {
998 for _, entry := range agents {
999 if entry.IsDir() {
1000 stores = append(stores, filepath.Join(agentsDir, entry.Name()))
1001 }
1002 }
1003 }
1004
1005 var matches []string
1006 for _, store := range stores {
1007 if err := contextErr(ctx); err != nil {
1008 return "", err
1009 }
1010 if err := collectManagedSessionMatches(ctx, store, id, &matches); err != nil {
1011 return "", err
1012 }
1013 }
1014 if err := contextErr(ctx); err != nil {
1015 return "", err
1016 }
1017 if len(matches) == 0 {
1018 return "", nil
1019 }
1020 if len(matches) > 1 {
1021 return "", fmt.Errorf("find managed session: UUID %q is ambiguous", id)
1022 }
1023 return matches[0], nil
1024}
1025
1026func collectManagedSessionMatches(ctx context.Context, root, id string, matches *[]string) error {
1027 if err := contextErr(ctx); err != nil {
1028 return err
1029 }
1030 dir := filepath.Join(root, "sessions")
1031 entries, err := os.ReadDir(dir)
1032 if errors.Is(err, os.ErrNotExist) {
1033 return nil
1034 }
1035 if err != nil {
1036 return fmt.Errorf("find managed session: read %q: %w", dir, err)
1037 }
1038 for _, bucket := range entries {
1039 if err := contextErr(ctx); err != nil {
1040 return err
1041 }
1042 if !bucket.IsDir() || bucket.Name() == "agents" || !isSessionBucketName(bucket.Name()) {
1043 continue
1044 }
1045 bucketPath := filepath.Join(dir, bucket.Name())
1046 files, err := os.ReadDir(bucketPath)
1047 if err != nil {
1048 return fmt.Errorf("find managed session: read %q: %w", bucketPath, err)
1049 }
1050 for _, file := range files {
1051 if err := contextErr(ctx); err != nil {
1052 return err
1053 }
1054 if file.IsDir() || !strings.HasSuffix(file.Name(), ".jsonl") {
1055 continue
1056 }
1057 path := filepath.Join(bucketPath, file.Name())
1058 meta, err := scanSessionMetaContext(ctx, path)
1059 if err != nil {
1060 return fmt.Errorf("find managed session: read metadata %q: %w", path, err)
1061 }
1062 if meta.ID == id {
1063 *matches = append(*matches, path)
1064 }
1065 }
1066 }
1067 return nil
1068}
1069
1070func isSessionBucketName(name string) bool {
1071 if len(name) != 16 {
1072 return false
1073 }
1074 for _, r := range name {
1075 if (r < '0' || r > '9') && (r < 'a' || r > 'f') {
1076 return false
1077 }
1078 }
1079 return true
1080}
1081
1082// firstUserPrompt scans forward from the current source position
1083// looking for the first user-role message and returns its text.
1084// Used to build a humane export filename. Uses Reader instead of
1085// Scanner so a very large JSONL row before the first user prompt
1086// cannot trip Scanner's token limit.
1087func firstUserPrompt(src io.Reader) (string, error) {
1088 r := bufio.NewReader(src)
1089 for {
1090 lineBytes, err := r.ReadBytes('\n')
1091 if len(lineBytes) > 0 {
1092 lineBytes = bytes.TrimRight(lineBytes, "\r\n")
1093 var line sessionLine
1094 if err := json.Unmarshal(lineBytes, &line); err == nil {
1095 if line.Type == "message" && line.Message != nil && line.Message.Role == "user" {
1096 b, _ := json.Marshal(line.Message)
1097 var m struct {
1098 Content []struct {
1099 Text string `json:"text"`
1100 } `json:"content"`
1101 }
1102 _ = json.Unmarshal(b, &m)
1103 for _, c := range m.Content {
1104 if c.Text != "" {
1105 return c.Text, nil
1106 }
1107 }
1108 }
1109 }
1110 }
1111 if err == io.EOF {
1112 return "", nil
1113 }
1114 if err != nil {
1115 return "", err
1116 }
1117 }
1118}
1119
1120// filenameFor builds a descriptive .zutsession filename from the
1121// session's start time and, when available, an excerpt of the
1122// first user prompt.
1123func filenameFor(started time.Time, id, firstPrompt string) string {
1124 base := started.UTC().Format("20060102-150405")
1125 if id != "" && len(id) >= 8 {
1126 base += "-" + id[:8]
1127 }
1128 slug := slugify(firstPrompt, 40)
1129 if slug != "" {
1130 base += "-" + slug
1131 }
1132 return base + PortableExt
1133}
1134
1135// slugify lowercases, strips punctuation, collapses whitespace to
1136// hyphens, and truncates to max runes so it's safe as a filename.
1137func slugify(s string, max int) string {
1138 s = strings.TrimSpace(strings.ToLower(s))
1139 if s == "" {
1140 return ""
1141 }
1142 var out strings.Builder
1143 prevDash := false
1144 for _, r := range s {
1145 switch {
1146 case r >= 'a' && r <= 'z', r >= '0' && r <= '9':
1147 out.WriteRune(r)
1148 prevDash = false
1149 default:
1150 if !prevDash && out.Len() > 0 {
1151 out.WriteByte('-')
1152 prevDash = true
1153 }
1154 }
1155 if out.Len() >= max {
1156 break
1157 }
1158 }
1159 return strings.TrimRight(out.String(), "-")
1160}