fix(briefing): greet for the actual time of day, not the period

[dannymcc]

Fixes #134 (reported by @davidfleischmann).

Problem

The AI briefing greeted with "morning" in the afternoon. The morning briefing period (last night's sleep + recovery) is shown right up until 17:00 by design, and the prompt hard-coded that framing — briefingSystemPrompt said "you write the morning health briefing … this morning's recovery" and the user prompt opened "Morning briefing for …". So a reader opening it at 3pm was handed "morning" and the model dutifully greeted with it.

Fix

Separate the greeting (which should follow the clock) from the period (a data-scope concept). generate() already has the current time, so:

• New partOfDay(now) → morning/afternoon/evening/night.
• The prompt is told the reader's real local time of day and to greet for that, never assuming another time; the morning/evening scope wording is now time-neutral (no "this morning").
• No "morning" leaks into a morning-period prompt viewed in the afternoon.

The morning/evening period still drives which data the briefing summarises — only the greeting now tracks the clock.

Tests

test/ai_briefing_test.dart: partOfDay boundaries, and that a morning-period prompt built for an afternoon reader says "currently afternoon" and never "morning".

Verified by inspection + unit tests (no SDK here to run flutter test); worth a quick on-device look that an afternoon briefing now reads right.

Closes #134

Summary by CodeRabbit

• New Features

  • Briefings now derive greeting and contextual header details from the reader’s local time of day.
  • Greeting guidance is generated for the current time-of-day bucket (morning/afternoon/evening/night) and stays consistent throughout the prompt.

• Bug Fixes

  • Prevented incorrect time-of-day greetings when the briefing period and local clock don’t match.
  • Briefings now use a single “effective now” timestamp for input collection and generation time.

• Tests

  • Updated prompt-building tests to cover explicit greeting inputs and clock-based behavior (including negative assertions).

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

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• lib/ai/briefing_engine.dart

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📝 Walkthrough

Walkthrough

Briefing prompt generation now derives the reader’s local time of day and passes it through system and user prompts, keeping greeting text independent from the briefing period. Tests cover the new arguments, time-based greeting behavior, and metric rendering.

Changes

Briefing time awareness

Layer / File(s)	Summary
Time-of-day prompt contract lib/ai/briefing_engine.dart, test/ai_briefing_test.dart	Adds partOfDay, extends both prompt builders with timeOfDay, updates greeting and header text, and tests mismatched period and greeting values.
Generation time wiring lib/ai/briefing_engine.dart	BriefingEngine.generate derives one effective timestamp, passes its local time-of-day label to both prompt builders, and uses it for generatedAtMs.

Estimated code review effort: 2 (Simple) | ~10 minutes

Suggested reviewers: abdulsaheel

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly matches the PR’s main change: using the reader’s actual time of day for briefing greetings.
Linked Issues check	✅ Passed	The change addresses issue #134 by deriving time of day from the reader’s clock and using it in briefing prompts.
Out of Scope Changes check	✅ Passed	The diff stays focused on briefing prompt/time handling and related tests, with no clear unrelated additions.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing Touches

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• Create PR with unit tests

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[coderabbitai]

Actionable comments posted: 1

🧹 Nitpick comments (1)

test/ai_briefing_test.dart (1)

124-138: 🎯 Functional Correctness | 🔵 Trivial | ⚡ Quick win

Cover the generation wiring, not only the pure builders.

This test passes 'afternoon' directly to both prompt builders, so it would still pass if BriefingEngine.generate stopped deriving or forwarding tod. Extend the generation test with a fixed afternoon now and assert the captured system and user prompts contain the local-time label.

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@test/ai_briefing_test.dart` around lines 124 - 138, Extend the
BriefingEngine.generate test to use a fixed afternoon now value and capture its
generated system and user prompts. Assert both prompts contain the corresponding
local-time label, verifying generate derives and forwards tod rather than
testing only briefingSystemPrompt and buildBriefingUserPrompt directly.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@lib/ai/briefing_engine.dart`:
- Around line 251-258: Capture a single effective timestamp at the start of the
briefing generation flow, using the provided now value or one DateTime.now()
fallback. Reuse it for todayLabel, partOfDay, collectBriefingInputs, and
generatedAtMs so all generated content shares the same time snapshot.

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Nitpick comments:
In `@test/ai_briefing_test.dart`:
- Around line 124-138: Extend the BriefingEngine.generate test to use a fixed
afternoon now value and capture its generated system and user prompts. Assert
both prompts contain the corresponding local-time label, verifying generate
derives and forwards tod rather than testing only briefingSystemPrompt and
buildBriefingUserPrompt directly.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

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Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 3d8df6a2-8c5d-4db0-b2e8-e07ef7aa8a87

📥 Commits

Reviewing files that changed from the base of the PR and between bae8f23 and b2a2e91.

📒 Files selected for processing (2)

• lib/ai/briefing_engine.dart
• test/ai_briefing_test.dart