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Building Forest + Grammarly Competitors in Flutter Web: Pomodoro Timer & AI Writing Assistant

#flutter #supabase #buildinpublic #ai

Building Forest + Grammarly Competitors in Flutter Web: Pomodoro Timer & AI Writing Assistant

What We Shipped

Three features in one session for 自分株式会社:

  1. Focus Timer (focus_timer_page.dart) — Pomodoro-style timer competing with Forest/Focusmate
  2. AI Writing Assistant (ai_writing_assistant_page.dart) — competing with Grammarly/Notion AI
  3. Abstinence Training Card — integrated into the home screen dashboard

Plus 5 new Edge Functions added to CI/CD.

Focus Timer: Edge Function + Timer.periodic

The Backend

focus-timer Edge Function manages focus_sessions records:

// GET ?action=stats&days=7
const { data: sessions } = await userClient
  .from("focus_sessions")
  .select("*")
  .eq("user_id", user.id)
  .gte("started_at", since)
  .order("started_at", { ascending: false });

const streak = _calculateStreak(sessions ?? []);
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Streak calculation: deduplicate dates with a Set, count consecutive days from today backward.

The Flutter Timer 

_timer = Timer.periodic(const Duration(seconds: 1), (_) {
  if (!mounted) return;
  setState(() {
    if (_remainingSeconds > 0) {
      _remainingSeconds--;
    } else {
      _completeSession();
    }
  });
});
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The session lifecycle:

  1. start → create DB record, store _activeSessionId
  2. Tick every second, decrement _remainingSeconds
  3. On complete or cancel → UPDATE the record with actual duration

Keeping _activeSessionId means the session is correctly marked even if the user navigates away mid-timer.

Colors.white08 Doesn't Exist

Quick gotcha: Flutter has no Colors.white08 shorthand. flutter analyze catches it as undefined_getter.

// WRONG — undefined
color: Colors.white08

// CORRECT
color: Colors.white.withValues(alpha: 0.08)
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AI Writing Assistant: Dart 3 Record Syntax for Actions

The Edge Function

ai-writing-assistant routes text to Gemini based on action:

case "improve":
  prompt = `Improve the following text for clarity and naturalness:\n\n${text}`;
  break;
case "titles":
  prompt = `Suggest 5 title options for the following content. Each under 20 words:\n\n${text}`;
  break;
case "summarize":
  prompt = `Summarize the following in 3 bullet points:\n\n${text}`;
  break;
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When GEMINI_API_KEY is unset, it returns a fallback message — no error thrown. Local development works without credentials.

Dart 3 Records for Action Definitions

Instead of enums + models, use Dart 3 record syntax:

static const _actions = {
  'improve':   ('Improve text',    Icons.auto_fix_high, Color(0xFF6366F1)),
  'summarize': ('Summarize',       Icons.compress,      Color(0xFF10B981)),
  'translate': ('Translate',       Icons.translate,     Color(0xFF8B5CF6)),
  'titles':    ('Title ideas',     Icons.title,         Color(0xFFF97316)),
  'minutes':   ('Meeting minutes', Icons.assignment,    Color(0xFF0EA5E9)),
};
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Access with e.value.$1 (label), e.value.$2 (icon), e.value.$3 (color). No separate class needed for a simple (label, icon, color) tuple.

Abstinence Training: Home Dashboard Integration

The abstinence training feature tracks "impulse purchases resisted." Five metrics from AbstinenceDisciplineSnapshot were added to the home screen:

  • repCount — total resistance events
  • moneySaved — estimated money saved (¥)
  • timeSavedMinutes — time not spent browsing
  • streakDays — consecutive days with no impulsive spending
  • stageLabel — current discipline level

One gotcha: _formatYen(int) expected double, not int:

// WRONG: argument_type_not_assignable
_formatYen(moneySaved)

// CORRECT
_formatYen(moneySaved.toDouble())
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flutter analyze catches this as argument_type_not_assignable.

6 Lint Errors Fixed

Error Fix
Colors.white08 undefined → Colors.white.withValues(alpha: 0.08)
prefer_const_declarations Add const to static definitions
require_trailing_commas Add trailing commas to all widget arguments
argument_type_not_assignable .toDouble() before passing int to double param
unnecessary_brace_in_string_interps '$streak' instead of '${streak}'
avoid_dynamic_calls Cast EF response to Map<String, dynamic>? first

All caught and fixed before commit. flutter analyze 0 errors maintained.

Summary

Feature Competing With Key Tech
Focus Timer Forest, Focusmate Timer.periodic + focus_sessions EF
AI Writing Grammarly, Notion AI Gemini + action-based EF routing
Abstinence Card — Dashboard integration via HomeSnapshot

Try it: 自分株式会社

buildinpublic #Flutter #Supabase #productivity #AI

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