fix(statusline): use configured timezone for today cost

[aukaukauk]

Fixes #778.

Summary

statusline computed today's date with Date.toISOString(), which always uses UTC. Daily usage is grouped using the local or configured timezone, so users far from UTC could see $0.00 today during date-boundary windows.

This changes statusline to compute the today filter with the same timezone-aware formatter used by daily grouping, passes that timezone into loadDailyUsageData, and exposes --timezone on the statusline command.

Verification

• pnpm --filter ccusage run format
• pnpm --filter ccusage typecheck
• pnpm --filter ccusage run test
• git diff --check origin/main...HEAD

Summary by CodeRabbit

Release Notes

• New Features
  • Added timezone configuration setting to statusline. This enables accurate date grouping and filtering based on your specified timezone instead of the system default, ensuring proper daily usage tracking across different regions.

[coderabbitai]

📝 Walkthrough

Walkthrough

This PR fixes issue #778 by adding timezone-aware "today" date filtering to the statusline command. A new getTodayDateFilter() helper replaces UTC-based string derivation, the config schema adds a timezone setting, and the statusline command now threads this timezone through to daily usage calculations.

Changes

Statusline Timezone-Aware Date Filtering

Layer / File(s)	Summary
Config Schema apps/ccusage/config-schema.json	Added timezone string property to statusline configuration schema with documentation noting it controls date grouping and defaults to system timezone.
Date Filter Helper apps/ccusage/src/commands/statusline.ts (lines 110–190)	Introduced getTodayDateFilter(timezone?) helper that computes YYYYMMDD "today" string using formatDate() with the provided timezone instead of UTC-based toISOString() derivation.
Command Integration apps/ccusage/src/commands/statusline.ts (lines 1–19, 243, 422–432)	Updated imports to include date formatting utilities and filesystem helpers; added timezone: sharedArgs.timezone to CLI arguments; passed mergedOptions.timezone to getTodayDateFilter() and loadDailyUsageData() for timezone-aligned cost filtering.
Tests & Validation apps/ccusage/src/commands/statusline.ts (lines 110–190)	Added guarded vitest tests validating timezone behavior across UTC, non-UTC, and boundary-crossing timezones; regression checks ensure timezone-aligned filtering preserves or excludes matching daily cost correctly.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• feat: add timezone option for date grouping #419: Introduces shared sharedArgs.timezone option that the main PR consumes in statusline and propagates across commands for unified timezone handling.
• fix: off-by-one compact date formatting #434: Fixes off-by-one behavior in compact date parsing; related because both PRs address date-formatting and timezone-handling logic.
• fix: use local timezone for date grouping instead of UTC #414: Switches date formatters to local timezone; directly related as both PRs refactor how date grouping respects timezones.

Suggested reviewers

• ryoppippi

Poem

🐰 Hops with joy, whiskers twitching in the light
UTC was wrong, now timezones align just right!
Perth's day is no longer lost to midnight's sight,
"Today" at last shows truth—no more zero blight! 🌍✨

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main fix: making statusline use the configured timezone for computing today's cost, directly addressing the core issue in PR #970.
Linked Issues check	✅ Passed	The PR fully addresses issue #778 by implementing timezone-aware computation for today's date, passing timezone through to daily usage loading, and exposing the --timezone CLI option.
Out of Scope Changes check	✅ Passed	All changes (config schema update, timezone-aware helper, CLI argument addition, and test coverage) are directly aligned with fixing the statusline timezone issue in #778.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[coderabbitai]

🧹 Nitpick comments (1)

apps/ccusage/src/commands/statusline.ts (1)

141-185: ⚡ Quick win

Switch this regression test to createFixture().

The manual mkdtempSync/writeFileSync setup bypasses the repo’s standard Claude-data fixture helper and makes this test harder to keep consistent with other ccusage tests. As per coding guidelines, use fs-fixture with createFixture() to simulate Claude data in tests.

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@apps/ccusage/src/commands/statusline.ts` around lines 141 - 185, Replace the
manual temp-dir and file setup (mkdtempSync, mkdirSync, writeFileSync, rmSync)
with the repo's fs-fixture createFixture() helper: create a fixture that mirrors
the previous layout (a .claude/projects/test-project/session-123.jsonl file
containing the same JSONL line), then call loadDailyUsageData(...) and
calculateTotals(...) as before; rely on createFixture() to handle fixture
creation and cleanup and remove the manual
mkdtempSync/mkdirSync/writeFileSync/rmSync logic so the test uses the standard
createFixture() flow.

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Nitpick comments:
In `@apps/ccusage/src/commands/statusline.ts`:
- Around line 141-185: Replace the manual temp-dir and file setup (mkdtempSync,
mkdirSync, writeFileSync, rmSync) with the repo's fs-fixture createFixture()
helper: create a fixture that mirrors the previous layout (a
.claude/projects/test-project/session-123.jsonl file containing the same JSONL
line), then call loadDailyUsageData(...) and calculateTotals(...) as before;
rely on createFixture() to handle fixture creation and cleanup and remove the
manual mkdtempSync/mkdirSync/writeFileSync/rmSync logic so the test uses the
standard createFixture() flow.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: c6d363dc-bbc7-4235-85e5-4e0574f4ea2a

📥 Commits

Reviewing files that changed from the base of the PR and between 1a4bd69 and dcc6197.

📒 Files selected for processing (2)

• apps/ccusage/config-schema.json
• apps/ccusage/src/commands/statusline.ts