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 now := time.Now()
495 timezone, timezoneOffset := localTimeMetadata(now)
496 name := fmt.Sprintf("%s-%s.jsonl", now.UTC().Format("20060102-150405"), newID[:8])
497 outPath := filepath.Join(dir, name)
498 // Build in a same-directory temporary file. Rename is atomic only when
499 // the temporary and final paths share a directory; closing the file first
500 // also ensures no buffered writer or descriptor can expose a partial branch.
501 dst, err := os.CreateTemp(dir, ".zut-branch-*.tmp")
502 if err != nil {
503 return "", fmt.Errorf("branch: create temp: %w", err)
504 }
505 tmpPath := dst.Name()
506 if err := dst.Chmod(0o644); err != nil {
507 _ = dst.Close()
508 _ = os.Remove(tmpPath)
509 return "", fmt.Errorf("branch: chmod temp: %w", err)
510 }
511 committed := false
512 defer func() {
513 _ = dst.Close()
514 if !committed {
515 _ = os.Remove(tmpPath)
516 _ = os.Remove(outPath)
517 }
518 }()
519 bw := bufio.NewWriter(dst)
520
521 branchMeta := SessionMeta{
522 ID: newID,
523 CWD: cwd,
524 Model: parent.Model,
525 Provider: parent.Provider,
526 Started: now.UTC(),
527 Version: version,
528 Timezone: timezone,
529 TimezoneOffset: timezoneOffset,
530 Parent: parent.ID,
531 ForkPoint: limit,
532 HideFromSessions: hideFromSessions,
533 CompactHandoff: append(json.RawMessage(nil), compactHandoff...),
534 Mission: missionAtBranch(parent, messages, limit),
535 Goal: cloneSessionGoal(goal),
536 GoalHistory: goalHistoryAtBranch(parent, messages, limit),
537 }
538 metaLine, err := json.Marshal(sessionLine{Type: "meta", Meta: &branchMeta})
539 if err != nil {
540 return "", fmt.Errorf("branch: marshal meta: %w", err)
541 }
542 if _, err := bw.Write(metaLine); err != nil {
543 return "", err
544 }
545 if err := bw.WriteByte('\n'); err != nil {
546 return "", err
547 }
548
549 for idx := 0; idx < limit; idx++ {
550 msg := messages[idx]
551 line, err := json.Marshal(sessionLine{Type: "message", Message: &msg})
552 if err != nil {
553 return "", fmt.Errorf("branch: marshal message %d: %w", idx, err)
554 }
555 if _, err := bw.Write(line); err != nil {
556 return "", err
557 }
558 if err := bw.WriteByte('\n'); err != nil {
559 return "", err
560 }
561 }
562
563 // Extension snapshots are branch state, not provider-visible transcript
564 // content. Write the latest snapshot that existed at the fork point so a
565 // child branch starts from the same extension state as its copied prefix.
566 extensionNames := make([]string, 0, len(extensionState))
567 for name := range extensionState {
568 extensionNames = append(extensionNames, name)
569 }
570 sort.Strings(extensionNames)
571 for _, name := range extensionNames {
572 line, err := json.Marshal(sessionLine{Type: "extension_state", Extension: name, State: extensionState[name]})
573 if err != nil {
574 return "", fmt.Errorf("branch: marshal extension state: %w", err)
575 }
576 if _, err := bw.Write(line); err != nil {
577 return "", fmt.Errorf("branch: write extension state: %w", err)
578 }
579 if err := bw.WriteByte('\n'); err != nil {
580 return "", fmt.Errorf("branch: terminate extension state row: %w", err)
581 }
582 }
583 // Preserve every cumulative checkpoint that belongs to this prefix. The
584 // final two rows are needed to reconstruct LastTurnUsage as a delta.
585 for _, checkpoint := range checkpoints {
586 if checkpoint.MessageCount > limit {
587 continue
588 }
589 usageLine, err := json.Marshal(sessionLine{
590 Type: "usage",
591 Usage: &checkpoint.Cumulative,
592 Cumulative: &checkpoint.Cumulative,
593 })
594 if err != nil {
595 return "", fmt.Errorf("branch: marshal usage: %w", err)
596 }
597 if _, err := bw.Write(usageLine); err != nil {
598 return "", err
599 }
600 if err := bw.WriteByte('\n'); err != nil {
601 return "", err
602 }
603 }
604
605 if err := bw.Flush(); err != nil {
606 return "", err
607 }
608 if err := dst.Sync(); err != nil {
609 return "", fmt.Errorf("branch: sync temp: %w", err)
610 }
611 if err := dst.Close(); err != nil {
612 return "", fmt.Errorf("branch: close temp: %w", err)
613 }
614 if err := os.Rename(tmpPath, outPath); err != nil {
615 return "", fmt.Errorf("branch: commit: %w", err)
616 }
617 committed = true
618 return outPath, nil
619}
620
621func lastUserText(msgs []provider.Message) string {
622 for i := len(msgs) - 1; i >= 0; i-- {
623 if msgs[i].Role != provider.RoleUser {
624 continue
625 }
626 if text := strings.TrimSpace(firstTextFromMessage(msgs[i])); text != "" {
627 return text
628 }
629 }
630 return ""
631}
632
633// TreeNode is one entry in the branch tree returned by
634// BuildSessionTree. Children are populated by linking on Parent ID.
635type TreeNode struct {
636 Summary SessionSummary
637 Meta SessionMeta
638 Children []*TreeNode
639}
640
641// BuildSessionTree loads every session in the cwd dir and returns
642// the forest rooted at parentless sessions, with each non-root
643// session placed under its parent. Used by /session tree to render
644// the branch hierarchy.
645func BuildSessionTree(root, cwd string) []*TreeNode {
646 dir := SessionsDir(root, cwd)
647 entries, err := os.ReadDir(dir)
648 if err != nil {
649 return nil
650 }
651 nodes := make(map[string]*TreeNode)
652 order := []string{}
653 for _, e := range entries {
654 if e.IsDir() || !strings.HasSuffix(e.Name(), ".jsonl") {
655 continue
656 }
657 path := filepath.Join(dir, e.Name())
658 summary := describeSession(path)
659 meta, _ := readSessionMeta(path)
660 if meta.ID == "" {
661 continue
662 }
663 nodes[meta.ID] = &TreeNode{Summary: summary, Meta: meta}
664 order = append(order, meta.ID)
665 }
666 return linkSessionTreeNodes(nodes, order)
667}
668
669// BuildSessionTreeStrict is the complete-read counterpart to the permissive
670// forest builder. It validates every session file before linking any node, so
671// callers that need a complete forest cannot silently omit malformed members.
672func BuildSessionTreeStrict(root, cwd string) ([]*TreeNode, error) {
673 dir := SessionsDir(root, cwd)
674 entries, err := os.ReadDir(dir)
675 if err != nil {
676 if errors.Is(err, os.ErrNotExist) {
677 return nil, nil
678 }
679 return nil, fmt.Errorf("build session tree: read directory: %w", err)
680 }
681 nodes := make(map[string]*TreeNode)
682 order := make([]string, 0, len(entries))
683 for _, e := range entries {
684 if e.IsDir() || !strings.HasSuffix(e.Name(), ".jsonl") {
685 continue
686 }
687 path := filepath.Join(dir, e.Name())
688 snapshot, err := ReadSessionSnapshot(path)
689 if err != nil {
690 return nil, fmt.Errorf("build session tree: read %q: %w", path, err)
691 }
692 if snapshot.Meta.ID == "" {
693 return nil, fmt.Errorf("build session tree: %q has no session id", path)
694 }
695 summary := SessionSummary{
696 Path: path,
697 Started: snapshot.Meta.Started,
698 Model: snapshot.Meta.Model,
699 Provider: snapshot.Meta.Provider,
700 MessageCount: len(snapshot.Messages),
701 FirstUserText: firstUserTextFromMessages(snapshot.Messages),
702 Title: snapshot.Meta.Title,
703 }
704 if len(snapshot.UsageCheckpoints) > 0 {
705 summary.TotalCost = snapshot.UsageCheckpoints[len(snapshot.UsageCheckpoints)-1].Cumulative.CostUSD
706 }
707 if _, exists := nodes[snapshot.Meta.ID]; exists {
708 return nil, fmt.Errorf("build session tree: duplicate session id %q", snapshot.Meta.ID)
709 }
710 nodes[snapshot.Meta.ID] = &TreeNode{Summary: summary, Meta: snapshot.Meta}
711 order = append(order, snapshot.Meta.ID)
712 }
713 return linkSessionTreeNodes(nodes, order), nil
714}
715
716// BuildSessionTreeFamilyStrict locates the current session using lightweight
717// metadata headers, then strictly validates only that root and its descendants.
718// A corrupt unrelated root in the same cwd bucket must not hide an otherwise
719// readable current family, while a corrupt member of the selected family still
720// fails the whole preflight.
721func BuildSessionTreeFamilyStrict(root, cwd, currentPath string) ([]*TreeNode, error) {
722 return BuildSessionTreeFamilyStrictContext(context.Background(), root, cwd, currentPath)
723}
724
725// BuildSessionTreeFamilyStrictContext is the cancellation-aware counterpart
726// to BuildSessionTreeFamilyStrict. It performs all filesystem reads on behalf
727// of callers that must remain responsive while a family is being discovered.
728func BuildSessionTreeFamilyStrictContext(ctx context.Context, root, cwd, currentPath string) ([]*TreeNode, error) {
729 roots, err := buildSessionTreeFamilyContext(ctx, root, cwd, currentPath)
730 if err != nil || len(roots) == 0 {
731 return roots, err
732 }
733 var validate func(*TreeNode) error
734 validate = func(node *TreeNode) error {
735 if err := contextErr(ctx); err != nil {
736 return err
737 }
738 snapshot, err := readSessionSnapshot(ctx, node.Summary.Path)
739 if err != nil {
740 return fmt.Errorf("build session family: read %q: %w", node.Summary.Path, err)
741 }
742 if snapshot.Meta.ID != node.Meta.ID {
743 return fmt.Errorf("build session family: session id changed in %q", node.Summary.Path)
744 }
745 node.Meta = snapshot.Meta
746 node.Summary = SessionSummary{
747 Path: node.Summary.Path,
748 Started: snapshot.Meta.Started,
749 Model: snapshot.Meta.Model,
750 Provider: snapshot.Meta.Provider,
751 MessageCount: len(snapshot.Messages),
752 FirstUserText: firstUserTextFromMessages(snapshot.Messages),
753 Title: snapshot.Meta.Title,
754 }
755 if len(snapshot.UsageCheckpoints) > 0 {
756 node.Summary.TotalCost = snapshot.UsageCheckpoints[len(snapshot.UsageCheckpoints)-1].Cumulative.CostUSD
757 }
758 for _, child := range node.Children {
759 if err := validate(child); err != nil {
760 return err
761 }
762 }
763 return nil
764 }
765 if err := validate(roots[0]); err != nil {
766 return nil, err
767 }
768 return roots, nil
769}
770
771// BuildSessionTreeFamilyContext discovers the current family from metadata
772// headers. Consumers that read every member themselves can start that work in
773// their preferred order without a redundant whole-family snapshot pass.
774func BuildSessionTreeFamilyContext(ctx context.Context, root, cwd, currentPath string) ([]*TreeNode, error) {
775 return buildSessionTreeFamilyContext(ctx, root, cwd, currentPath)
776}
777
778func buildSessionTreeFamilyContext(ctx context.Context, root, cwd, currentPath string) ([]*TreeNode, error) {
779 if err := contextErr(ctx); err != nil {
780 return nil, err
781 }
782 if currentPath == "" {
783 return nil, errors.New("build session family: current path is empty")
784 }
785 dir := SessionsDir(root, cwd)
786 entries, err := os.ReadDir(dir)
787 if err != nil {
788 if errors.Is(err, os.ErrNotExist) {
789 return nil, nil
790 }
791 return nil, fmt.Errorf("build session family: read directory: %w", err)
792 }
793 cleanCurrent := filepath.Clean(currentPath)
794 nodes := make(map[string]*TreeNode)
795 order := make([]string, 0, len(entries))
796 for _, entry := range entries {
797 if err := contextErr(ctx); err != nil {
798 return nil, err
799 }
800 if entry.IsDir() || !strings.HasSuffix(entry.Name(), ".jsonl") {
801 continue
802 }
803 path := filepath.Join(dir, entry.Name())
804 meta, err := readSessionMetaHeader(path)
805 if err != nil {
806 if filepath.Clean(path) == cleanCurrent {
807 return nil, fmt.Errorf("build session family: read current metadata %q: %w", path, err)
808 }
809 // A file whose header is unreadable cannot be associated with the
810 // selected family. Valid descendants are linked below and fully
811 // preflighted; unrelated corrupt roots stay out of this family.
812 continue
813 }
814 if _, exists := nodes[meta.ID]; exists {
815 return nil, fmt.Errorf("build session family: duplicate session id %q", meta.ID)
816 }
817 nodes[meta.ID] = &TreeNode{
818 Summary: SessionSummary{Path: path, Started: meta.Started, Model: meta.Model, Provider: meta.Provider},
819 Meta: meta,
820 }
821 order = append(order, meta.ID)
822 }
823 roots := linkSessionTreeNodes(nodes, order)
824 var familyRoot *TreeNode
825 for _, candidate := range roots {
826 if treeNodeContainsPath(candidate, cleanCurrent) {
827 familyRoot = candidate
828 break
829 }
830 }
831 if familyRoot == nil {
832 return nil, fmt.Errorf("build session family: current path %q is not in the session forest", currentPath)
833 }
834 return []*TreeNode{familyRoot}, nil
835}
836
837func readSessionMetaHeader(path string) (SessionMeta, error) {
838 f, err := os.Open(path)
839 if err != nil {
840 return SessionMeta{}, err
841 }
842 defer f.Close()
843 line, err := bufio.NewReader(f).ReadBytes('\n')
844 if err != nil && len(line) == 0 {
845 return SessionMeta{}, err
846 }
847 line = bytes.TrimSpace(line)
848 var row sessionLine
849 if err := json.Unmarshal(line, &row); err != nil {
850 return SessionMeta{}, err
851 }
852 if row.Type != "meta" || row.Meta == nil || row.Meta.ID == "" {
853 return SessionMeta{}, errors.New("first row is not a valid meta row")
854 }
855 return *row.Meta, nil
856}
857
858func treeNodeContainsPath(node *TreeNode, path string) bool {
859 if node == nil {
860 return false
861 }
862 if filepath.Clean(node.Summary.Path) == filepath.Clean(path) {
863 return true
864 }
865 for _, child := range node.Children {
866 if treeNodeContainsPath(child, path) {
867 return true
868 }
869 }
870 return false
871}
872
873func linkSessionTreeNodes(nodes map[string]*TreeNode, order []string) []*TreeNode {
874 var roots []*TreeNode
875 for _, id := range order {
876 n := nodes[id]
877 if n.Meta.Parent == "" {
878 roots = append(roots, n)
879 continue
880 }
881 if parent, ok := nodes[n.Meta.Parent]; ok {
882 parent.Children = append(parent.Children, n)
883 } else {
884 // Parent file missing (was manually deleted). Treat as a root so it
885 // still shows up in the tree.
886 roots = append(roots, n)
887 }
888 }
889 return roots
890}
891
892// scanSessionMeta reads JSONL rows without hydrating transcript content and
893// returns the latest valid metadata row. Listing and ID lookup only need this
894// small projection; full snapshot validation remains the responsibility of
895// resume, export, branching, and tree preflight callers.
896func scanSessionMeta(path string) (meta SessionMeta, err error) {
897 return scanSessionMetaContext(context.Background(), path)
898}
899
900func scanSessionMetaContext(ctx context.Context, path string) (meta SessionMeta, err error) {
901 if err := contextErr(ctx); err != nil {
902 return SessionMeta{}, err
903 }
904 f, err := os.Open(path)
905 if err != nil {
906 return SessionMeta{}, err
907 }
908 defer f.Close()
909
910 var sawMeta bool
911 err = forEachStrictJSONLLineContext(ctx, f, func(line []byte, lineNo int) error {
912 var head sessionLineHead
913 if err := json.Unmarshal(line, &head); err != nil {
914 return fmt.Errorf("line %d: invalid JSON: %w", lineNo, err)
915 }
916 if head.Type == "" {
917 return fmt.Errorf("line %d: missing row type", lineNo)
918 }
919 if !sawMeta && head.Type != "meta" {
920 return fmt.Errorf("line %d: first row is not meta", lineNo)
921 }
922 switch head.Type {
923 case "meta":
924 var row struct {
925 Meta *SessionMeta `json:"meta"`
926 }
927 if err := json.Unmarshal(line, &row); err != nil {
928 return fmt.Errorf("line %d: invalid meta row: %w", lineNo, err)
929 }
930 if row.Meta == nil || row.Meta.ID == "" {
931 return fmt.Errorf("line %d: meta row has no session id", lineNo)
932 }
933 meta = *row.Meta
934 sawMeta = true
935 case "message", "compaction", "usage", "rename", "extension_state":
936 // These rows are intentionally not hydrated here.
937 default:
938 return fmt.Errorf("line %d: unknown row type %q", lineNo, head.Type)
939 }
940 return nil
941 })
942 if err != nil {
943 return SessionMeta{}, fmt.Errorf("session metadata %q: %w", path, err)
944 }
945 if !sawMeta {
946 return SessionMeta{}, fmt.Errorf("session metadata %q: file is empty", path)
947 }
948 return meta, nil
949}
950
951// readSessionMeta returns the latest validated metadata for path without
952// reconstructing its transcript. Full snapshot validation is performed by
953// callers that need messages rather than listing metadata.
954func readSessionMeta(path string) (SessionMeta, error) {
955 return scanSessionMeta(path)
956}
957
958// FindSessionByID looks up a session file in root/cwd whose meta id
959// matches. Used by /session tree when the user picks an entry. O(n)
960// over the files in the dir; the list is small in practice.
961func FindSessionByID(root, cwd, id string) string {
962 dir := SessionsDir(root, cwd)
963 entries, err := os.ReadDir(dir)
964 if err != nil {
965 return ""
966 }
967 for _, e := range entries {
968 if e.IsDir() || !strings.HasSuffix(e.Name(), ".jsonl") {
969 continue
970 }
971 path := filepath.Join(dir, e.Name())
972 meta, err := scanSessionMeta(path)
973 if err != nil {
974 continue
975 }
976 if meta.ID == id {
977 return path
978 }
979 }
980 return ""
981}
982
983// FindManagedSessionByID looks up a session UUID across zut's managed
984// session stores, independent of cwd. A nil error and empty path mean no
985// matching session was found. Read, storage, metadata, and duplicate-ID
986// failures are returned to the caller instead of being reported as a miss.
987func FindManagedSessionByID(ctx context.Context, root, id string) (string, error) {
988 if strings.TrimSpace(root) == "" {
989 return "", errors.New("find managed session: root is empty")
990 }
991 if strings.TrimSpace(id) == "" {
992 return "", errors.New("find managed session: id is empty")
993 }
994
995 stores := []string{root}
996 agentsDir := filepath.Join(root, "sessions", "agents")
997 agents, err := os.ReadDir(agentsDir)
998 if err != nil && !errors.Is(err, os.ErrNotExist) {
999 return "", fmt.Errorf("find managed session: read agent stores: %w", err)
1000 }
1001 if err == nil {
1002 for _, entry := range agents {
1003 if entry.IsDir() {
1004 stores = append(stores, filepath.Join(agentsDir, entry.Name()))
1005 }
1006 }
1007 }
1008
1009 var matches []string
1010 for _, store := range stores {
1011 if err := contextErr(ctx); err != nil {
1012 return "", err
1013 }
1014 if err := collectManagedSessionMatches(ctx, store, id, &matches); err != nil {
1015 return "", err
1016 }
1017 }
1018 if err := contextErr(ctx); err != nil {
1019 return "", err
1020 }
1021 if len(matches) == 0 {
1022 return "", nil
1023 }
1024 if len(matches) > 1 {
1025 return "", fmt.Errorf("find managed session: UUID %q is ambiguous", id)
1026 }
1027 return matches[0], nil
1028}
1029
1030func collectManagedSessionMatches(ctx context.Context, root, id string, matches *[]string) error {
1031 if err := contextErr(ctx); err != nil {
1032 return err
1033 }
1034 dir := filepath.Join(root, "sessions")
1035 entries, err := os.ReadDir(dir)
1036 if errors.Is(err, os.ErrNotExist) {
1037 return nil
1038 }
1039 if err != nil {
1040 return fmt.Errorf("find managed session: read %q: %w", dir, err)
1041 }
1042 for _, bucket := range entries {
1043 if err := contextErr(ctx); err != nil {
1044 return err
1045 }
1046 if !bucket.IsDir() || bucket.Name() == "agents" || !isSessionBucketName(bucket.Name()) {
1047 continue
1048 }
1049 bucketPath := filepath.Join(dir, bucket.Name())
1050 files, err := os.ReadDir(bucketPath)
1051 if err != nil {
1052 return fmt.Errorf("find managed session: read %q: %w", bucketPath, err)
1053 }
1054 for _, file := range files {
1055 if err := contextErr(ctx); err != nil {
1056 return err
1057 }
1058 if file.IsDir() || !strings.HasSuffix(file.Name(), ".jsonl") {
1059 continue
1060 }
1061 path := filepath.Join(bucketPath, file.Name())
1062 meta, err := scanSessionMetaContext(ctx, path)
1063 if err != nil {
1064 return fmt.Errorf("find managed session: read metadata %q: %w", path, err)
1065 }
1066 if meta.ID == id {
1067 *matches = append(*matches, path)
1068 }
1069 }
1070 }
1071 return nil
1072}
1073
1074func isSessionBucketName(name string) bool {
1075 if len(name) != 16 {
1076 return false
1077 }
1078 for _, r := range name {
1079 if (r < '0' || r > '9') && (r < 'a' || r > 'f') {
1080 return false
1081 }
1082 }
1083 return true
1084}
1085
1086// firstUserPrompt scans forward from the current source position
1087// looking for the first user-role message and returns its text.
1088// Used to build a humane export filename. Uses Reader instead of
1089// Scanner so a very large JSONL row before the first user prompt
1090// cannot trip Scanner's token limit.
1091func firstUserPrompt(src io.Reader) (string, error) {
1092 r := bufio.NewReader(src)
1093 for {
1094 lineBytes, err := r.ReadBytes('\n')
1095 if len(lineBytes) > 0 {
1096 lineBytes = bytes.TrimRight(lineBytes, "\r\n")
1097 var line sessionLine
1098 if err := json.Unmarshal(lineBytes, &line); err == nil {
1099 if line.Type == "message" && line.Message != nil && line.Message.Role == "user" {
1100 b, _ := json.Marshal(line.Message)
1101 var m struct {
1102 Content []struct {
1103 Text string `json:"text"`
1104 } `json:"content"`
1105 }
1106 _ = json.Unmarshal(b, &m)
1107 for _, c := range m.Content {
1108 if c.Text != "" {
1109 return c.Text, nil
1110 }
1111 }
1112 }
1113 }
1114 }
1115 if err == io.EOF {
1116 return "", nil
1117 }
1118 if err != nil {
1119 return "", err
1120 }
1121 }
1122}
1123
1124// filenameFor builds a descriptive .zutsession filename from the
1125// session's start time and, when available, an excerpt of the
1126// first user prompt.
1127func filenameFor(started time.Time, id, firstPrompt string) string {
1128 base := started.UTC().Format("20060102-150405")
1129 if id != "" && len(id) >= 8 {
1130 base += "-" + id[:8]
1131 }
1132 slug := slugify(firstPrompt, 40)
1133 if slug != "" {
1134 base += "-" + slug
1135 }
1136 return base + PortableExt
1137}
1138
1139// slugify lowercases, strips punctuation, collapses whitespace to
1140// hyphens, and truncates to max runes so it's safe as a filename.
1141func slugify(s string, max int) string {
1142 s = strings.TrimSpace(strings.ToLower(s))
1143 if s == "" {
1144 return ""
1145 }
1146 var out strings.Builder
1147 prevDash := false
1148 for _, r := range s {
1149 switch {
1150 case r >= 'a' && r <= 'z', r >= '0' && r <= '9':
1151 out.WriteRune(r)
1152 prevDash = false
1153 default:
1154 if !prevDash && out.Len() > 0 {
1155 out.WriteByte('-')
1156 prevDash = true
1157 }
1158 }
1159 if out.Len() >= max {
1160 break
1161 }
1162 }
1163 return strings.TrimRight(out.String(), "-")
1164}