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