fix(devin): treat session timestamps as epoch seconds (#1322)

The Devin CLI stores created_at and last_activity_at as Unix epoch
seconds, but the parser treated them as milliseconds. This produced
dates in 1970 that were discarded as invalid, leaving started_at and
ended_at NULL for every Devin session.

Replace devinUnixMilli (time.UnixMilli) with devinUnixSec (time.Unix)
and correct the FileMtime multiplier from 1e6 to 1e9. The same fix
applies to message_nodes.created_at, which is also epoch seconds.

Rename variables and test helpers from the misleading MS/Millis suffixes
to match the Devin DB column names. Update all test data from 13-digit
millisecond values to 10-digit second values.

Add timestamp-unit evidence to the Devin provenance entry.

I tested this and confirmed it fixes #1199

---------

Co-authored-by: Matthew Jacobs <mjacobs@apache.org>

Author: JohnRiv

docs/internal/session-format-sources.md

@@ -820,7 +820,14 @@ Grok section and remove the explicit registry exception in the coverage test.
 ## Devin CLI (`devin`)
 
 - **Format:** `cli/sessions.db` for session metadata plus transcript JSON
-  artifacts.
+  artifacts. The `sessions.created_at`, `sessions.last_activity_at`, and
+  `message_nodes.created_at` columns are Unix epoch seconds (not milliseconds).
+  Verified against a live Devin CLI database 2026-07-31, and reverified
+  independently against CLI 3000.3.22 the same day. Because the unit is observed
+  rather than documented, the parser rejects values outside the
+  nanosecond-representable epoch-second range instead of converting them, so a
+  future unit change surfaces as missing timestamps rather than as a silently
+  overflowed far-future mtime that would wedge resync.
 - **Evidence:** `no-public-source`.
 - **Upstream:** Cognition's first-party
   [Devin documentation](https://docs.devin.ai/) and public repositories were

internal/db/db.go

@@ -350,7 +350,18 @@ const projectIdentityRemoteScrubCompletedKey = "project_identity_remote_scrub_v1
 // project identity snapshots that older mapping behavior could persist with
 // the mapped target label before incremental ingestion is allowed to reuse
 // them.)
-const dataVersion = 77
+//
+// (78: Devin timestamp reparse. The Devin parser read sessions.created_at,
+// sessions.last_activity_at, and message_nodes.created_at as epoch
+// milliseconds when Devin writes epoch seconds, so every existing Devin row
+// carries 1970-era started_at/ended_at and message timestamps that were
+// discarded as invalid. Existing rows need re-parsing to backfill real
+// timestamps. A fingerprint change alone cannot cover this: for a message-node
+// fallback session whose sessions row has no usable created_at or
+// last_activity_at, the Devin fingerprint hashes only raw epoch integers and
+// zero-time metadata, so it is byte-identical before and after the fix and
+// incremental sync would skip the correction.)
+const dataVersion = 78
 
 const tokenCoverageRepairStatsKey = "token_coverage_repair_v1"
 

internal/db/db_test.go

@@ -1008,9 +1008,10 @@ func TestMigration_ToolResultEventsTable(t *testing.T) {
 		"expected tool_result_events table after reopen")
 }
 
-func TestCurrentDataVersionVibeCachedTokensAndProjectIdentityReparse(t *testing.T) {
-	assert.Equal(t, 77, CurrentDataVersion(),
-		"version 77 reparses Vibe usage and project identity snapshots")
+func TestCurrentDataVersionDevinEpochSecondsReparse(t *testing.T) {
+	assert.Equal(t, 78, CurrentDataVersion(),
+		"version 78 reparses Devin sessions whose timestamps were read as "+
+			"milliseconds and stored as 1970 dates")
 }
 
 func TestInsertMessages_PreservesToolResultEvents(t *testing.T) {

internal/parser/devin.go

@@ -6,6 +6,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"math"
 	"os"
 	"path/filepath"
 	"strings"
@@ -86,27 +87,27 @@ func ForEachDevinSessionMeta(
 
 	for rows.Next() {
 		var meta DevinSessionMeta
-		var createdAtMS int64
-		var lastActivityMS sql.NullInt64
-		var updatedAtMS int64
+		var createdAt int64
+		var lastActivity sql.NullInt64
+		var updatedAt int64
 		if err := rows.Scan(
 			&meta.RawSessionID,
 			&meta.Title,
 			&meta.CWD,
 			&meta.Model,
-			&createdAtMS,
-			&lastActivityMS,
-			&updatedAtMS,
+			&createdAt,
+			&lastActivity,
+			&updatedAt,
 		); err != nil {
 			return fmt.Errorf("scanning devin session meta: %w", err)
 		}
 		meta.VirtualPath = VirtualSourcePath(dbPath, meta.RawSessionID)
-		meta.CreatedAt = devinUnixMilli(createdAtMS)
-		if lastActivityMS.Valid {
-			meta.LastActivity = devinUnixMilli(lastActivityMS.Int64)
+		meta.CreatedAt = devinUnixSec(createdAt)
+		if lastActivity.Valid {
+			meta.LastActivity = devinUnixSec(lastActivity.Int64)
 		}
-		meta.UpdatedAt = devinUnixMilli(updatedAtMS)
-		meta.FileMtime = updatedAtMS * 1_000_000
+		meta.UpdatedAt = devinUnixSec(updatedAt)
+		meta.FileMtime = devinFileMtimeNS(updatedAt)
 		observeStreamingDiscoveryBuffer(ctx, 1)
 		if err := yield(meta); err != nil {
 			return err
@@ -137,9 +138,9 @@ func getDevinSessionMeta(
 	defer db.Close()
 
 	var meta DevinSessionMeta
-	var createdAtMS int64
-	var lastActivityMS sql.NullInt64
-	var updatedAtMS int64
+	var createdAt int64
+	var lastActivity sql.NullInt64
+	var updatedAt int64
 	err = db.QueryRow(`
 		SELECT id,
 		       COALESCE(title, ''),
@@ -156,9 +157,9 @@ func getDevinSessionMeta(
 		&meta.Title,
 		&meta.CWD,
 		&meta.Model,
-		&createdAtMS,
-		&lastActivityMS,
-		&updatedAtMS,
+		&createdAt,
+		&lastActivity,
+		&updatedAt,
 	)
 	if err != nil {
 		if err == sql.ErrNoRows {
@@ -168,20 +169,46 @@ func getDevinSessionMeta(
 	}
 
 	meta.VirtualPath = VirtualSourcePath(dbPath, meta.RawSessionID)
-	meta.CreatedAt = devinUnixMilli(createdAtMS)
-	if lastActivityMS.Valid {
-		meta.LastActivity = devinUnixMilli(lastActivityMS.Int64)
+	meta.CreatedAt = devinUnixSec(createdAt)
+	if lastActivity.Valid {
+		meta.LastActivity = devinUnixSec(lastActivity.Int64)
 	}
-	meta.UpdatedAt = devinUnixMilli(updatedAtMS)
-	meta.FileMtime = updatedAtMS * 1_000_000
+	meta.UpdatedAt = devinUnixSec(updatedAt)
+	meta.FileMtime = devinFileMtimeNS(updatedAt)
 	return &meta, nil
 }
 
-func devinUnixMilli(ms int64) time.Time {
-	if ms <= 0 {
+// devinMaxEpochSec is the largest epoch-second value whose nanosecond form
+// still fits in int64 (year 2262). Anything larger is not a plausible Devin
+// timestamp and signals a unit mismatch -- a 13-digit millisecond value, for
+// example. Rejecting it keeps a bad column from silently overflowing into a
+// far-future mtime, which would wedge change detection: devinApplyFileInfoTimes
+// only ever raises Mtime, so a wrapped value can never be superseded and the
+// session would stop resyncing.
+const devinMaxEpochSec = math.MaxInt64 / int64(time.Second)
+
+// devinPlausibleEpochSec reports whether sec is a usable Devin epoch-second
+// timestamp. Devin stores created_at, last_activity_at, and
+// message_nodes.created_at as Unix seconds.
+func devinPlausibleEpochSec(sec int64) bool {
+	return sec > 0 && sec <= devinMaxEpochSec
+}
+
+func devinUnixSec(sec int64) time.Time {
+	if !devinPlausibleEpochSec(sec) {
 		return time.Time{}
 	}
-	return time.UnixMilli(ms).UTC()
+	return time.Unix(sec, 0).UTC()
+}
+
+// devinFileMtimeNS converts a Devin epoch-second timestamp to the nanosecond
+// mtime the sync layer compares against. Implausible values yield 0, which
+// callers already treat as "no synthetic mtime available".
+func devinFileMtimeNS(sec int64) int64 {
+	if !devinPlausibleEpochSec(sec) {
+		return 0
+	}
+	return sec * int64(time.Second)
 }
 
 type devinTranscriptError struct {
@@ -406,7 +433,7 @@ type devinMessageNodeRow struct {
 	NodeID       int64
 	ParentNodeID sql.NullInt64
 	ChatMessage  string
-	CreatedAtMS  int64
+	CreatedAt    int64
 }
 
 func listDevinMessageNodes(dbPath, rawSessionID string) ([]devinMessageNodeRow, error) {
@@ -434,7 +461,7 @@ func listDevinMessageNodes(dbPath, rawSessionID string) ([]devinMessageNodeRow,
 	var nodes []devinMessageNodeRow
 	for rows.Next() {
 		var row devinMessageNodeRow
-		if err := rows.Scan(&row.RowID, &row.NodeID, &row.ParentNodeID, &row.ChatMessage, &row.CreatedAtMS); err != nil {
+		if err := rows.Scan(&row.RowID, &row.NodeID, &row.ParentNodeID, &row.ChatMessage, &row.CreatedAt); err != nil {
 			return nil, err
 		}
 		nodes = append(nodes, row)
@@ -489,7 +516,7 @@ func parseDevinDBMessageNode(
 		Role:          role,
 		Content:       content,
 		ThinkingText:  thinking,
-		Timestamp:     devinUnixMilli(row.CreatedAtMS),
+		Timestamp:     devinUnixSec(row.CreatedAt),
 		HasThinking:   hasThinking,
 		HasToolUse:    hasToolUse || len(toolCalls) > 0,
 		IsSystem:      isSystem,

internal/parser/devin_provider.go

@@ -473,13 +473,13 @@ func devinAppendMessageNodesFingerprint(h io.Writer, dbPath, rawSessionID string
 	if err != nil {
 		return err
 	}
-	var maxCreatedAtMS int64
+	var maxCreatedAt int64
 	for _, node := range nodes {
-		if node.CreatedAtMS > maxCreatedAtMS {
-			maxCreatedAtMS = node.CreatedAtMS
+		if node.CreatedAt > maxCreatedAt {
+			maxCreatedAt = node.CreatedAt
 		}
 	}
-	if _, err := fmt.Fprintf(h, "message_nodes\x00count\x00%d\x00max_created\x00%d\x00", len(nodes), maxCreatedAtMS); err != nil {
+	if _, err := fmt.Fprintf(h, "message_nodes\x00count\x00%d\x00max_created\x00%d\x00", len(nodes), maxCreatedAt); err != nil {
 		return err
 	}
 	for _, node := range nodes {
@@ -490,7 +490,7 @@ func devinAppendMessageNodesFingerprint(h io.Writer, dbPath, rawSessionID string
 			node.NodeID,
 			node.ParentNodeID.Valid,
 			node.ParentNodeID.Int64,
-			node.CreatedAtMS,
+			node.CreatedAt,
 			len(node.ChatMessage),
 		); err != nil {
 			return err