feat(tui): Add Monthly tab for model-by-month usage tracking

[kang-heewon]

Summary

• TUI에 Monthly 탭을 추가하여 월 × 모델 교차 테이블 표시
• 전체 기간 기준 월평균 비용/토큰 계산 (테이블 하단 AVG/MO 행)
• 정렬(d/t/c), 스크롤, 반응형 컬럼 지원
• tokscale monthly CLI → Monthly 탭 리다이렉트

Changes

• MonthlyModelUsage struct 및 monthly_models/total_months 필드 추가
• aggregate_messages()에 monthly 집계 로직 추가 (GroupBy 지원)
• Tab::Monthly variant 및 get_sorted_monthly() 함수 추가
• monthly.rs UI 모듈 생성 (daily.rs 패턴 기반)
• UI dispatcher/footer에 Monthly 통합
• 관련 테스트 업데이트

Test plan

• cargo clippy --package tokscale-cli 경고 없음
• cargo build --package tokscale-cli 성공
• cargo test --package tokscale-cli Tab 관련 테스트 통과
• TUI 실행 시 6개 탭 표시 확인
• Monthly 탭에서 데이터 렌더링 확인

Notes

• 3개 기존 테스트(test_data_loader_*, test_handle_key_increase_decrease_refresh)는 main 브랜치에서도 실패하는 기존 이슈입니다.

---

Summary by cubic

Adds a Monthly tab to the TUI for model-by-month usage tracking with sorting, scrolling, and an AVG/MO row. Monthly data is now aggregated during load, and tokscale monthly opens this tab.

• New Features
  • Monthly aggregation added to DataLoader with MonthlyModelUsage, plus monthly_models and total_months.
  • New Tab::Monthly with Date/Cost/Tokens sorting, selection, scroll, and footer count.
  • New monthly UI: responsive columns (Month/Model/Provider/Client/Tokens/Cost), current month highlight, AVG/MO row, scrollbar, empty state.
  • CLI: tokscale monthly now redirects to the Monthly tab.

^{Written for commit 81c06eb. Summary will update on new commits.}

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[cubic-dev-ai]

2 issues found across 7 files

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="crates/tokscale-cli/src/tui/cache.rs">

<violation number="1" location="crates/tokscale-cli/src/tui/cache.rs:335">
P2: Monthly usage data is never serialized/deserialized in the cache; the new fields are always reset to empty/zero, so cached loads render an empty Monthly tab.</violation>
</file>

<file name="crates/tokscale-cli/src/tui/ui/monthly.rs">

<violation number="1" location="crates/tokscale-cli/src/tui/ui/monthly.rs:259">
P3: Scrollbar is drawn over the full inner block (`area.inner(...)`) even when the AVG/MO footer row is reserved, so it overlaps/mismatches the footer; it should use `table_area` for the scrollbar height.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}

[cubic-dev-ai]

P2: Monthly usage data is never serialized/deserialized in the cache; the new fields are always reset to empty/zero, so cached loads render an empty Monthly tab.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At crates/tokscale-cli/src/tui/cache.rs, line 335:

<comment>Monthly usage data is never serialized/deserialized in the cache; the new fields are always reset to empty/zero, so cached loads render an empty Monthly tab.</comment>

<file context>
@@ -332,6 +332,8 @@ impl TryFrom<CachedUsageData> for UsageData {
             models: u.models.into_iter().map(|m| m.into()).collect(),
             agents: u.agents.into_iter().map(|a| a.into()).collect(),
             daily: daily?,
+            monthly_models: Vec::new(),
+            total_months: 0,
             graph: graph.transpose()?,
</file context>

[cubic-dev-ai]

P3: Scrollbar is drawn over the full inner block (area.inner(...)) even when the AVG/MO footer row is reserved, so it overlaps/mismatches the footer; it should use table_area for the scrollbar height.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At crates/tokscale-cli/src/tui/ui/monthly.rs, line 259:

<comment>Scrollbar is drawn over the full inner block (`area.inner(...)`) even when the AVG/MO footer row is reserved, so it overlaps/mismatches the footer; it should use `table_area` for the scrollbar height.</comment>

<file context>
@@ -0,0 +1,282 @@
+
+        frame.render_stateful_widget(
+            scrollbar,
+            area.inner(Margin {
+                horizontal: 0,
+                vertical: 1,
</file context>

Suggested change

	area.inner(Margin {
	table_area.inner(Margin {
	horizontal: 0,
	vertical: 1,
	}),