feat(energy): Phase 3 — match-my-energy task sort + tri-state tag column

Closes Phase 3 of the 2026-04-23 feature-complete roadmap. Incorporates
the Codex plan-review fixes from this session: profile-free index, tri-
state update command, and de-prioritise-not-hide semantics.

Storage (kon-storage):
- Migration v11 adds `energy TEXT` to `tasks` with a CHECK constraint on
  `high | medium | brain_dead | NULL`. Index `(energy, created_at DESC)`
  — deliberately not per-profile because the tasks table carries no
  profile_id column yet (tracked as a separate gap in HANDOVER).
- `TaskRow.energy: Option<String>` plus `task_row_from` read.
- `insert_task` signature grows by one optional arg (`energy`). Allowed
  `too_many_arguments` with a rationale comment — the positional shape
  matches the column order and flipping to a params struct would have
  rippled through every caller for cosmetic benefit only.
- New `set_task_energy(pool, id, Option<&str>) -> TaskRow`. Lives as its
  own function because `update_task` uses COALESCE to let `None` mean
  "preserve" — which would make clearing the tag impossible.
- Two new tests: round-trip including explicit NULL clear, and CHECK
  constraint rejection of unknown values.
- Tests updated for the v10 → v11 version bump.

Tauri (src-tauri):
- `TaskDto.energy`. `CreateTaskRequest.energy` (optional). Inline
  validation against the allowed set before hitting the DB, so frontend
  bugs surface as friendly errors instead of CHECK-constraint failures.
- New `set_task_energy_cmd` command mirroring the storage tri-state API.

Frontend (svelte):
- `EnergyLevel` type added to `types/app.ts`. `TaskDto`, `TaskEntry`, and
  `TaskDraft` grow an `energy` field.
- `SettingsState.currentEnergy` (persisted) + `matchMyEnergy` (persisted
  toggle). Defaults: null + false — no surface change until user opts in.
- `setTaskEnergy(id, EnergyLevel | null)` action on the task store.
  Calls the dedicated Tauri command, updates local state, broadcasts to
  sibling windows.
- `EnergyChip.svelte` — new component. Cycles unset → High → Medium →
  Brain-Dead → unset on click. Colour tokens: accent / warning /
  text-tertiary (deliberately not danger-red for Brain-Dead — the brief
  is explicit that this state must not feel pathologised).
- Chip rendered on every task row in TasksPage and every row in
  WipTaskList. Hidden-until-hover when energy is unset so untagged rows
  stay calm; always visible once tagged because the colour is the signal.
- Tasks page header gains a "I feel" segmented control and a
  "Match my energy" toggle. When both are active, matching tasks sort
  to the top — unset tasks are treated as Medium-equivalent. Nothing is
  ever hidden; this is a de-prioritisation, not a filter.

Deferred / out of scope:
- LLM-driven surfacing (brief says "The AI surfaces...") — deterministic
  client-side sort is v1; LLM layer is a later phase.
- tasks.profile_id + per-profile energy sort — separate migration.

All green: cargo build + 251 tests + clippy -D warnings (0 warnings)
+ fmt + svelte-check (0/0) + npm run build.

src-tauri/src/commands/tasks.rs

@@ -12,8 +12,9 @@ use kon_storage::{
     delete_task as db_delete_task, get_task_by_id as db_get_task,
     insert_subtask as db_insert_subtask, insert_task as db_insert_task,
     list_feedback_examples as db_list_feedback_examples, list_subtasks as db_list_subtasks,
-    list_tasks as db_list_tasks, uncomplete_task as db_uncomplete_task,
-    update_task as db_update_task, FeedbackRow, FeedbackTargetType, TaskRow,
+    list_tasks as db_list_tasks, set_task_energy as db_set_task_energy,
+    uncomplete_task as db_uncomplete_task, update_task as db_update_task, FeedbackRow,
+    FeedbackTargetType, TaskRow,
 };
 
 use crate::AppState;
@@ -33,6 +34,7 @@ pub struct TaskDto {
     pub created_at: String,
     pub source_transcript_id: Option<String>,
     pub parent_task_id: Option<String>,
+    pub energy: Option<String>,
 }
 
 impl From<TaskRow> for TaskDto {
@@ -49,10 +51,27 @@ impl From<TaskRow> for TaskDto {
             created_at: r.created_at,
             source_transcript_id: r.source_transcript_id,
             parent_task_id: r.parent_task_id,
+            energy: r.energy,
         }
     }
 }
 
+/// Accepted energy tag values. Kept as a const so frontend and storage
+/// validate against the same list. Migration v11 enforces the same
+/// set via a CHECK constraint.
+const ENERGY_LEVELS: &[&str] = &["high", "medium", "brain_dead"];
+
+fn validate_energy(raw: Option<&str>) -> Result<Option<&str>, String> {
+    match raw {
+        None => Ok(None),
+        Some(s) if ENERGY_LEVELS.contains(&s) => Ok(Some(s)),
+        Some(other) => Err(format!(
+            "energy must be one of {:?} or null, got {:?}",
+            ENERGY_LEVELS, other
+        )),
+    }
+}
+
 #[derive(Debug, Deserialize)]
 #[serde(rename_all = "camelCase")]
 pub struct CreateTaskRequest {
@@ -65,6 +84,8 @@ pub struct CreateTaskRequest {
     pub list_id: Option<String>,
     #[serde(default)]
     pub effort: Option<String>,
+    #[serde(default)]
+    pub energy: Option<String>,
 }
 
 #[tauri::command]
@@ -72,6 +93,7 @@ pub async fn create_task_cmd(
     state: tauri::State<'_, AppState>,
     request: CreateTaskRequest,
 ) -> Result<TaskDto, String> {
+    let energy = validate_energy(request.energy.as_deref())?;
     db_insert_task(
         &state.db,
         &request.id,
@@ -80,6 +102,7 @@ pub async fn create_task_cmd(
         request.source_transcript_id.as_deref(),
         request.list_id.as_deref(),
         request.effort.as_deref(),
+        energy,
     )
     .await
     .map_err(|e| e.to_string())?;
@@ -168,6 +191,24 @@ pub async fn uncomplete_task_cmd(
         .map_err(|e| e.to_string())
 }
 
+/// Phase 3: set or clear the `energy` tag on a task. Dedicated command
+/// rather than a field on `update_task_cmd` because the existing update
+/// path uses `COALESCE` semantics where `None` means "preserve" — which
+/// makes clearing the tag impossible. This command always writes exactly
+/// what you send, including `None` to explicitly clear.
+#[tauri::command]
+pub async fn set_task_energy_cmd(
+    state: tauri::State<'_, AppState>,
+    id: String,
+    energy: Option<String>,
+) -> Result<TaskDto, String> {
+    let validated = validate_energy(energy.as_deref())?;
+    let row = db_set_task_energy(&state.db, &id, validated)
+        .await
+        .map_err(|e| e.to_string())?;
+    Ok(TaskDto::from(row))
+}
+
 /// Convert HITL feedback rows fetched from storage into the few-shot
 /// exemplar shape the LLM crate consumes. We reconstruct the `input`
 /// (parent task text, transcript chunk) from `context_json` where the

src-tauri/src/lib.rs

@@ -284,6 +284,7 @@ pub fn run() {
             commands::tasks::complete_task_cmd,
             commands::tasks::delete_task_cmd,
             commands::tasks::uncomplete_task_cmd,
+            commands::tasks::set_task_energy_cmd,
             commands::tasks::decompose_and_store,
             commands::tasks::extract_tasks_from_transcript_cmd,
             commands::tasks::list_subtasks_cmd,