feat(ui): add MicroSteps component with expandable micro-steps in WipTaskList

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/lib/components/MicroSteps.svelte

@@ -0,0 +1,132 @@
+<script>
+  import { onMount } from 'svelte';
+  import { invoke } from '@tauri-apps/api/core';
+  import { Check, Timer, Loader2 } from 'lucide-svelte';
+  import { getPreferences } from '$lib/stores/preferences.svelte.js';
+
+  const prefs = getPreferences();
+
+  let { parentTaskId } = $props();
+
+  let steps = $state([]);
+  let loading = $state(false);
+  let error = $state('');
+
+  let reduceMotion = $derived(
+    prefs.accessibility?.reduceMotion === 'on'
+    || (prefs.accessibility?.reduceMotion === 'system'
+      && typeof window !== 'undefined'
+      && window.matchMedia('(prefers-reduced-motion: reduce)').matches)
+  );
+
+  onMount(() => {
+    loadSteps();
+  });
+
+  async function loadSteps() {
+    loading = true;
+    error = '';
+    try {
+      steps = await invoke('list_subtasks', { parentTaskId });
+    } catch (e) {
+      error = typeof e === 'string' ? e : 'Failed to load micro-steps';
+      console.error('Failed to load subtasks:', e);
+    } finally {
+      loading = false;
+    }
+  }
+
+  async function toggleStep(step) {
+    if (step.done) return; // Already done — no uncomplete for micro-steps
+    try {
+      const parentCompleted = await invoke('complete_subtask', { subtaskId: step.id });
+      // Update local state
+      const idx = steps.findIndex(s => s.id === step.id);
+      if (idx >= 0) {
+        steps[idx].done = true;
+        steps[idx].status = 'done';
+      }
+      // If parent was auto-completed, notify via event so task list refreshes
+      if (parentCompleted) {
+        window.dispatchEvent(new CustomEvent('kon:tasks-changed'));
+      }
+    } catch (e) {
+      console.error('Failed to complete micro-step:', e);
+    }
+  }
+
+  function startTimer(step) {
+    window.dispatchEvent(new CustomEvent('kon:start-timer', {
+      detail: { id: step.id, text: step.text, duration: 120 }
+    }));
+  }
+
+  let allDone = $derived(steps.length > 0 && steps.every(s => s.done));
+  let doneCount = $derived(steps.filter(s => s.done).length);
+</script>
+
+<div class="pl-6 border-l-2 border-border-subtle ml-2 mt-1 mb-2"
+  class:animate-fade-in={!reduceMotion}>
+
+  {#if loading}
+    <div class="flex items-center gap-2 py-3 text-text-tertiary">
+      <Loader2 size={14} class="animate-spin" aria-hidden="true" />
+      <span class="text-[11px]">Breaking down task…</span>
+    </div>
+  {:else if error}
+    <p class="text-[11px] text-text-tertiary py-2">{error}</p>
+  {:else if steps.length === 0}
+    <p class="text-[11px] text-text-tertiary py-2">No micro-steps yet</p>
+  {:else}
+    <div class="flex flex-col gap-0.5">
+      {#each steps as step (step.id)}
+        <div class="flex items-center gap-2 px-2 py-1.5 rounded-lg group
+          {step.done ? 'opacity-50' : 'hover:bg-hover'}"
+          style="transition-duration: var(--duration-ui)">
+
+          <!-- Checkbox -->
+          <button
+            class="w-3.5 h-3.5 rounded border flex-shrink-0 flex items-center justify-center
+              {step.done
+                ? 'border-accent bg-accent/20'
+                : 'border-border-subtle hover:border-accent'}"
+            onclick={() => toggleStep(step)}
+            aria-label={step.done ? 'Completed' : 'Complete micro-step'}
+            disabled={step.done}
+          >
+            {#if step.done}
+              <Check size={10} class="text-accent" aria-hidden="true" />
+            {/if}
+          </button>
+
+          <!-- Step text -->
+          <span class="text-[12px] flex-1 min-w-0
+            {step.done ? 'text-text-tertiary line-through' : 'text-text'}">
+            {step.text}
+          </span>
+
+          <!-- Just Start timer button -->
+          {#if !step.done}
+            <button
+              class="text-text-tertiary hover:text-accent opacity-0 group-hover:opacity-100"
+              style="transition: opacity var(--duration-ui)"
+              onclick={() => startTimer(step)}
+              aria-label="Just start — 2 minutes"
+              title="Just start — 2 minutes"
+            >
+              <Timer size={12} aria-hidden="true" />
+            </button>
+          {/if}
+        </div>
+      {/each}
+    </div>
+
+    <!-- Progress -->
+    <p class="text-[10px] text-text-tertiary mt-1 px-2">
+      {doneCount}/{steps.length} steps done
+      {#if allDone}
+        <span class="text-success ml-1">— all done</span>
+      {/if}
+    </p>
+  {/if}
+</div>

src/lib/components/WipTaskList.svelte

@@ -1,23 +1,48 @@
 <script>
-  import { getTasks, createTask, completeTask, deleteTask } from '$lib/stores/tasks.svelte.js';
+  import { onMount } from 'svelte';
+  import { invoke } from '@tauri-apps/api/core';
+  import { getTasks, createTask, completeTask, deleteTask, loadTasks } from '$lib/stores/tasks.svelte.js';
   const tasks = getTasks();
-  import { ChevronDown, Timer } from 'lucide-svelte';
-
-  function startTimer(task, duration = 120) {
-    window.dispatchEvent(new CustomEvent('kon:start-timer', {
-      detail: { id: task.id, text: task.text, duration }
-    }));
-  }
+  import { ChevronDown, ChevronUp, Timer, ListTree, Loader2 } from 'lucide-svelte';
+  import MicroSteps from './MicroSteps.svelte';
 
   let { wipLimit = 3 } = $props();
 
   let newTaskText = $state('');
   let showOverflow = $state(false);
+  let expandedTaskIds = $state(new Set());
+  let decomposing = $state(new Set());
+  let hasChildren = $state(new Map());
 
   let activeTasks = $derived(tasks.filter(t => !t.done));
   let visibleTasks = $derived(activeTasks.slice(0, wipLimit));
   let overflowTasks = $derived(activeTasks.slice(wipLimit));
-  let hasOverflow = $derived(overflowTasks.length > 0);
+  let hasOverflowTasks = $derived(overflowTasks.length > 0);
+
+  // Check which tasks have children on mount and when tasks change
+  onMount(() => {
+    checkChildrenStatus();
+    window.addEventListener('kon:tasks-changed', onTasksChanged);
+    return () => window.removeEventListener('kon:tasks-changed', onTasksChanged);
+  });
+
+  async function onTasksChanged() {
+    await loadTasks();
+    await checkChildrenStatus();
+  }
+
+  async function checkChildrenStatus() {
+    for (const task of activeTasks) {
+      try {
+        const subtasks = await invoke('list_subtasks', { parentTaskId: task.id });
+        hasChildren.set(task.id, subtasks.length > 0);
+      } catch {
+        // Tauri not available — ignore
+      }
+    }
+    // Trigger reactivity
+    hasChildren = new Map(hasChildren);
+  }
 
   async function handleAdd() {
     const text = newTaskText.trim();
@@ -29,6 +54,44 @@
   function handleKeydown(e) {
     if (e.key === 'Enter') handleAdd();
   }
+
+  function toggleExpand(taskId) {
+    const next = new Set(expandedTaskIds);
+    if (next.has(taskId)) {
+      next.delete(taskId);
+    } else {
+      next.add(taskId);
+    }
+    expandedTaskIds = next;
+  }
+
+  async function decomposeTask(task) {
+    const next = new Set(decomposing);
+    next.add(task.id);
+    decomposing = next;
+
+    try {
+      await invoke('decompose_and_store', { parentTaskId: task.id });
+      // Mark as having children and expand
+      hasChildren.set(task.id, true);
+      hasChildren = new Map(hasChildren);
+      const expanded = new Set(expandedTaskIds);
+      expanded.add(task.id);
+      expandedTaskIds = expanded;
+    } catch (e) {
+      console.error('Decompose failed:', e);
+    } finally {
+      const done = new Set(decomposing);
+      done.delete(task.id);
+      decomposing = done;
+    }
+  }
+
+  function startTimer(task, duration = 120) {
+    window.dispatchEvent(new CustomEvent('kon:start-timer', {
+      detail: { id: task.id, text: task.text, duration }
+    }));
+  }
 </script>
 
 <div class="flex flex-col gap-3">
@@ -51,6 +114,7 @@
   {:else}
     <div class="flex flex-col gap-1">
       {#each visibleTasks as task (task.id)}
+        <div>
           <div class="flex items-center gap-2 px-3 py-2 rounded-lg hover:bg-hover group"
             style="transition-duration: var(--duration-ui)">
             <button
@@ -61,6 +125,37 @@
             >
             </button>
             <span class="text-[13px] text-text flex-1 min-w-0 truncate">{task.text}</span>
+
+            <!-- Expand/Decompose button -->
+            {#if hasChildren.get(task.id)}
+              <button
+                class="text-text-tertiary hover:text-text-secondary"
+                style="transition: color var(--duration-ui)"
+                onclick={() => toggleExpand(task.id)}
+                aria-label={expandedTaskIds.has(task.id) ? 'Collapse micro-steps' : 'Expand micro-steps'}
+              >
+                {#if expandedTaskIds.has(task.id)}
+                  <ChevronUp size={14} aria-hidden="true" />
+                {:else}
+                  <ChevronDown size={14} aria-hidden="true" />
+                {/if}
+              </button>
+            {:else if decomposing.has(task.id)}
+              <Loader2 size={14} class="text-accent animate-spin" aria-hidden="true" />
+            {:else}
+              <button
+                class="flex items-center gap-1 text-text-tertiary hover:text-accent opacity-0 group-hover:opacity-100 text-[10px]"
+                style="transition: opacity var(--duration-ui)"
+                onclick={() => decomposeTask(task)}
+                aria-label="Break down into micro-steps"
+                title="Break down"
+              >
+                <ListTree size={12} aria-hidden="true" />
+                <span>Break down</span>
+              </button>
+            {/if}
+
+            <!-- Timer button -->
             <button
               class="text-text-tertiary hover:text-accent opacity-0 group-hover:opacity-100"
               style="transition: opacity var(--duration-ui)"
@@ -70,6 +165,7 @@
             >
               <Timer size={14} aria-hidden="true" />
             </button>
+
             <button
               class="text-text-tertiary hover:text-danger opacity-0 group-hover:opacity-100 text-[11px]"
               onclick={() => deleteTask(task.id)}
@@ -78,12 +174,18 @@
               &times;
             </button>
           </div>
+
+          <!-- Expanded micro-steps -->
+          {#if expandedTaskIds.has(task.id)}
+            <MicroSteps parentTaskId={task.id} />
+          {/if}
+        </div>
       {/each}
     </div>
   {/if}
 
   <!-- Overflow -->
-  {#if hasOverflow}
+  {#if hasOverflowTasks}
     <button
       class="flex items-center gap-1.5 text-[11px] text-text-tertiary hover:text-text-secondary px-3"
       onclick={() => showOverflow = !showOverflow}