fix(mcp): correct project name and cost time-bucket bugs from wave 1

- health_tools: use resolveProjectName instead of filepath.Base for the
  active session project name; filepath.Base returned the raw hash dir
  (e.g. -Users-dayna-blackwell-code-commitmux) not the friendly name

- cost_tools: anchor today/week bucket logic on last UserMessageTimestamp
  instead of StartTime so resumed multi-day sessions count toward the
  correct time buckets; falls back to StartTime when timestamps are empty

Author: blackwell-systems

CHANGELOG.md

@@ -8,7 +8,11 @@ All notable changes to claudewatch are documented here.
 
 - **`get_cost_summary` live session gap** — the current in-progress session was invisible to cost aggregates, causing a ~$212 hole in today/week/all-time totals and by-project breakdowns. `handleGetCostSummary` now calls `FindActiveSessionPath` + `ParseActiveSession` after loading indexed sessions, deduplicates by SessionID to prevent double-counting if the session closes between calls, and applies the same time-bucket and by-project logic as indexed sessions. Non-fatal: any active session error falls through to indexed-only path.
 
-- **`get_project_health` wrong default** — with no `project` arg the tool sorted indexed sessions by `StartTime` and picked the most recent closed session, which was wrong when a session was actively running. The default now checks for an active session first via `FindActiveSessionPath` + `ParseActiveSession`, uses `filepath.Base(meta.ProjectPath)` as the project name, and falls back to the existing sort-by-StartTime logic only when no active session is available. Priority: explicit arg > active session > most-recent indexed session.
+- **`get_project_health` wrong default** — with no `project` arg the tool sorted indexed sessions by `StartTime` and picked the most recent closed session, which was wrong when a session was actively running. The default now checks for an active session first via `FindActiveSessionPath` + `ParseActiveSession`, resolves the project name via `resolveProjectName` (not `filepath.Base`, which returned the raw hash directory), and falls back to the existing sort-by-StartTime logic only when no active session is available. Priority: explicit arg > active session > most-recent indexed session.
+
+- **`get_project_health` active-session project name** — `filepath.Base(meta.ProjectPath)` returned the hashed directory name (e.g. `-Users-dayna-blackwell-code-commitmux`) instead of the friendly project name. Fixed by using `resolveProjectName(meta.SessionID, meta.ProjectPath, tags)`, consistent with how indexed sessions resolve names.
+
+- **`get_cost_summary` today/week undercounting for resumed sessions** — time-bucket logic used `session.StartTime` to decide whether a session counted toward `today_usd` or `week_usd`. Long-running sessions resumed across day or week boundaries had a start time in the past, causing their cost to appear in neither bucket. Fixed by anchoring on the last entry in `UserMessageTimestamps` (most recent user activity), falling back to `StartTime` only when the timestamps list is empty.
 
 ### Added
 

internal/mcp/cost_tools.go

@@ -68,7 +68,7 @@ func (s *Server) handleGetCostSummary(args json.RawMessage) (any, error) {
 		cost := analyzer.EstimateSessionCost(session, pricing, ratio)
 		allTimeUSD += cost
 
-		t := claude.ParseTimestamp(session.StartTime)
+		t := lastActiveTime(session.UserMessageTimestamps, session.StartTime)
 		if !t.IsZero() {
 			tUTC := t.UTC()
 			if tUTC.Format("2006-01-02") == todayStr {
@@ -98,7 +98,7 @@ func (s *Server) handleGetCostSummary(args json.RawMessage) (any, error) {
 			liveCost := analyzer.EstimateSessionCost(*liveMeta, pricing, ratio)
 			allTimeUSD += liveCost
 
-			t := claude.ParseTimestamp(liveMeta.StartTime)
+			t := lastActiveTime(liveMeta.UserMessageTimestamps, liveMeta.StartTime)
 			if !t.IsZero() {
 				tUTC := t.UTC()
 				if tUTC.Format("2006-01-02") == todayStr {
@@ -145,3 +145,16 @@ func (s *Server) handleGetCostSummary(args json.RawMessage) (any, error) {
 		ByProject:  projectSpends,
 	}, nil
 }
+
+// lastActiveTime returns the timestamp of the most recent user message in the session,
+// falling back to startTime if UserMessageTimestamps is empty. This avoids misclassifying
+// long-running resumed sessions as inactive on their original start date.
+func lastActiveTime(userMsgTimestamps []string, startTime string) time.Time {
+	for i := len(userMsgTimestamps) - 1; i >= 0; i-- {
+		t := claude.ParseTimestamp(userMsgTimestamps[i])
+		if !t.IsZero() {
+			return t
+		}
+	}
+	return claude.ParseTimestamp(startTime)
+}

internal/mcp/health_tools.go

@@ -61,7 +61,7 @@ func (s *Server) handleGetProjectHealth(args json.RawMessage) (any, error) {
 		if activeErr == nil && activePath != "" {
 			meta, parseErr := claude.ParseActiveSession(activePath)
 			if parseErr == nil && meta != nil && meta.ProjectPath != "" {
-				project = filepath.Base(meta.ProjectPath)
+				project = resolveProjectName(meta.SessionID, meta.ProjectPath, tags)
 			}
 		}