fix(web): keep repository tasks on worktree defaults (#2136)

docs/specs/tasks/task-create-executor-default.md

@@ -0,0 +1,76 @@
+---
+status: approved
+created: 2026-08-01
+owner: Kandev
+decision: ADR-2026-08-01-repository-task-executor-defaults
+---
+
+# Task Create Executor Default
+
+## Why
+
+Repository-backed tasks should start in isolated workspaces unless the user or workspace has made
+an explicit contrary choice. A portable last-used Local executor profile must not silently turn a
+later ordinary task into an in-place run, including after a Kandev update or in another browser.
+
+## Broken behavior
+
+The task-create dialog currently restores a valid backend-owned last-used executor profile before
+it resolves the task source and workspace default. After any Local task, that portable preference
+can therefore select Local for the next ordinary repository-backed task even when the workspace
+has no Local default.
+
+## What
+
+- The task-create dialog resolves the default executor before it considers the last-used executor
+  profile.
+- An ordinary repository-backed task uses the workspace's valid configured default executor; when
+  the workspace has no valid default, it uses Worktree when Worktree is available.
+- A task with no repository, or a task created from an explicit unmanaged local path, continues to
+  prefer a direct Local executor.
+- The backend-owned last-used executor profile may refine the profile choice only when that profile
+  belongs to the already-resolved default executor. It cannot switch the executor.
+- A valid explicit workspace default, including Local, remains authoritative.
+- A user may manually select a different executor profile for the task being created. Successful
+  task creation continues to record that profile in backend user settings, but the recorded value
+  does not override the next task's executor policy.
+- If the preferred executor or its profiles are unavailable, the dialog uses the existing eligible
+  fallback so task creation remains usable.
+- Desktop and mobile use the same selection policy. This change does not alter dialog composition,
+  touch behavior, or responsive layout.
+
+## Persistence guarantees
+
+`users.settings.task_create_last_used.executor_profile_id` remains a portable backend-owned user
+preference as defined by [ADR 0028](../../decisions/0028-task-create-last-used-source-of-truth.md)
+and [ADR 0041](../../decisions/0041-backend-owned-portable-user-settings.md). No browser storage,
+schema migration, or new persistence field is introduced. The stored profile is a convenience
+within the executor selected by policy, not a portable override of that policy.
+
+## Scenarios
+
+- **GIVEN** an ordinary repository-backed task, no workspace executor default, and a last-used
+  Local profile, **WHEN** the user opens Create Task, **THEN** a Worktree profile is selected.
+- **GIVEN** the same backend user settings are opened in a different browser or after an update,
+  **WHEN** the user opens an ordinary repository-backed task dialog, **THEN** the same Worktree
+  safety default is selected.
+- **GIVEN** an ordinary repository-backed task and an explicit Local workspace default, **WHEN**
+  the user opens Create Task, **THEN** a Local profile is selected even if the last-used profile is
+  Worktree.
+- **GIVEN** an explicit unmanaged local path or no repository, **WHEN** the user opens Create Task,
+  **THEN** a direct Local profile is preferred.
+- **GIVEN** Worktree is the resolved executor and the last-used profile is another valid Worktree
+  profile, **WHEN** the dialog restores selections, **THEN** that Worktree profile is selected.
+- **GIVEN** Local was selected manually for one ordinary task and the workspace still has no
+  executor default, **WHEN** the next ordinary repository-backed task dialog opens, **THEN** it
+  returns to Worktree.
+- **GIVEN** the preferred executor has no usable profile, **WHEN** the dialog resolves defaults,
+  **THEN** it selects the first existing eligible fallback rather than leaving an invalid profile.
+
+## Out of scope
+
+- Removing backend persistence for task-create selections.
+- Adding per-executor last-used profile history.
+- Preventing users from manually choosing Local for an ordinary task.
+- Changing workspace executor settings or their explicit precedence.
+- Changing task-create dialog layout or mobile interaction patterns.