From f969d77da8e28a04e844b1c051896e9b3e1e0ecb Mon Sep 17 00:00:00 2001
From: Ash Shah <494shah@gmail.com>
Date: Sun, 9 Aug 2026 15:28:37 -0700
Subject: [PATCH] fix: show the empty state when the selected file leaves the
 working copy
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

`resolveSection` returns null once the path is in no list — its last change was
committed or discarded, so the file is no longer part of the working copy. But
`diffKey` tested only `selectedFile`, so it stayed non-empty and the effect
fetched an unstaged diff for a file with nothing to diff. No row could
highlight, since the row test already requires a matching section, while the
pane rendered an empty diff instead of "Select a file to view its diff."

Gate both on `section !== null` rather than clearing the selection: no state
written from a derived or an effect, and it keeps the "follow the file wherever
it went" behaviour the section resolution exists for — if the path comes back,
the selection resumes instead of having been silently dropped.

Reported by Codex review on the v0.4.0 promotion (#30).

Verified by reading plus `npm run check`; there is no WorkingCopyView test
harness, and the path is behind `isTauri()` so the browser preview cannot reach
it either. npm run check 530 files 0 errors; npm test 388 passed;
cargo test 232 + 7.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
---
 src/lib/components/WorkingCopyView.svelte | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/src/lib/components/WorkingCopyView.svelte b/src/lib/components/WorkingCopyView.svelte
index 3113e9a..9ac6c0f 100644
--- a/src/lib/components/WorkingCopyView.svelte
+++ b/src/lib/components/WorkingCopyView.svelte
@@ -104,8 +104,13 @@
   // monotonic revision counter (workingChangesRev) instead of the file count so that
   // a hunk stage/unstage — which doesn't change the file count but does re-index
   // hunks on the backend — also triggers a re-fetch and prevents stale hunk indices.
+  // `section` is null once the path is in NO list — its last change was committed or
+  // discarded, so the file is no longer part of the working copy. Keying on `selectedFile`
+  // alone kept the key non-empty there and fetched an unstaged diff for a file with nothing
+  // to diff: no row could highlight (the row test already requires a matching section), while
+  // the pane showed an empty diff instead of the nothing-selected state.
   const diffKey = $derived(
-    selectedFile !== null
+    selectedFile !== null && section !== null
       ? `${selectedFile}::${section}::${selectedIsUntracked}::${appState.workingChangesRev}::${appState.effectiveDiffContext}`
       : "",
   );
@@ -570,7 +575,9 @@
 
       <!-- ── Diff pane (right column) ─────────────────────────────────────────── -->
       <div class="diff-pane">
-        {#if !selectedFile}
+        <!-- `section === null` means the selected path has left the working copy entirely, so
+             there is nothing to show and no row is highlighted — same state as no selection. -->
+        {#if !selectedFile || section === null}
           <p class="diff-loading">Select a file to view its diff.</p>
         {:else if diffLoading}
           <p class="diff-loading">Loading diff…</p>