fix(shelley): per-world lazycue diff fixture to avoid parallel-step race

The lazycue suite now runs as two parallel Buildkite steps (vue + react) that
can land on the same agent and share /tmp. Both processes set up the diff-viewer
git fixture at the same fixed path (/tmp/shelley-lazycue-diff-fixture) via
setupDiffFixtureRepo (os.RemoveAll + git init), so they raced: one process's
RemoveAll ran while the other's `git init` was writing .git/hooks, panicking
with "unlinkat .../.git/hooks: directory not empty" and failing the step.

Suffix the fixture path with the world (…-vue / …-react) so each process owns
its own fixture. The path is still deterministic per world, so the LazyCue
description that embeds it hashes to a stable per-world cache key. Regenerated
the two cached DSL entries with the new paths (mechanical path swap + rehash,
no behavior change); verified both worlds hit cache and pass.

Prompt: Now the "vue-rebuild now at ..." lines look ugly. And the Pierre diffs are ugly too. (Follow-up: the parallel lazycue steps from the earlier CI change raced on a shared /tmp fixture.)
Co-authored-by: Shelley <shelley@exe.dev>

Author: 2 people

test/lazycue_test.go

@@ -432,9 +432,17 @@ func TestDiffViewerListsAddedModifiedDeleted(t *testing.T) {
 
 // diffFixtureDir is a deterministic path holding a git repo with working-tree
 // changes (a modified, a deleted, and a brand-new untracked file). The diff
-// viewer's file list is loaded from here. The path is stable so the LazyCue
-// description that references it hashes to a consistent cache key.
-var diffFixtureDir = filepath.Join(os.TempDir(), "shelley-lazycue-diff-fixture")
+// viewer's file list is loaded from here.
+//
+// The path is per-world: the vue and react lazycue suites run as separate
+// processes that may share an agent's /tmp, and a single fixed path would race
+// (one process's RemoveAll+git-init stomping the other's, panicking on
+// "directory not empty"). The world suffix keeps each process's fixture
+// isolated while staying deterministic so the LazyCue description that embeds
+// the path hashes to a consistent per-world cache key. lazycueWorld() reads
+// LAZYCUE_WORLD, which the harness sets before the process starts, so it is
+// valid at package init.
+var diffFixtureDir = filepath.Join(os.TempDir(), "shelley-lazycue-diff-fixture-"+lazycueWorld())
 
 // setupDiffFixtureRepo (re)creates a git repo at dir with three kinds of
 // working-tree change: a modified tracked file, a deleted tracked file, and a

…zycue/.lazycue/vue/7244604f6f935fb5.json …cue/.lazycue/react/c96aac0bb66135be.jsonui/lazycue/.lazycue/vue/7244604f6f935fb5.json renamed to ui/lazycue/.lazycue/react/c96aac0bb66135be.json ui/lazycue/.lazycue/vue/7244604f6f935fb5.json renamed to ui/lazycue/.lazycue/react/c96aac0bb66135be.json

@@ -1,11 +1,11 @@
 {
   "_README": "This file is managed by LazyCue (see shelley/lazycue). Do NOT edit by hand — it is the cached, machine-generated DSL for a self-healing browser test. To change behavior, edit the test description and re-run LazyCue.",
-  "description": "Navigate to /new?diff=working\u0026cwd=/tmp/shelley-lazycue-diff-fixture . This opens the git diff viewer for the working-tree changes of that repository. Wait for the file picker (a \u003cselect\u003e element with selector \"select.diff-viewer-select\") to be visible. The working tree has exactly four changed files, each appearing as an \u003coption\u003e in that select with a status-symbol prefix: a modified file shown as \"~ tracked_mod.txt\", a deleted file shown as \"- tracked_del.txt\", a brand-new untracked file shown as \"+ untracked_added.txt\", and a modified committed file whose name contains a space shown as \"~ spaced name.txt\". Verify all four options are present, with their full untruncated paths, by running an eval step whose expression is \"(() =\u003e { const opts = Array.from(document.querySelectorAll('select.diff-viewer-select option')).map(o =\u003e o.textContent.trim()); const has = (sym, name) =\u003e opts.some(t =\u003e t.startsWith(sym) \u0026\u0026 t.includes(name)); return has('+','untracked_added.txt') \u0026\u0026 has('~','tracked_mod.txt') \u0026\u0026 has('-','tracked_del.txt') \u0026\u0026 has('~','spaced name.txt') ? 'true' : 'false'; })()\" and expect the result \"true\". Two regression cases matter here: the untracked (added) file must be present with the \"+\" prefix, and the committed file with a space must appear as the full \"spaced name.txt\" (not truncated at the space to \"spaced\").",
+  "description": "Navigate to /new?diff=working\u0026cwd=/tmp/shelley-lazycue-diff-fixture-react . This opens the git diff viewer for the working-tree changes of that repository. Wait for the file picker (a \u003cselect\u003e element with selector \"select.diff-viewer-select\") to be visible. The working tree has exactly four changed files, each appearing as an \u003coption\u003e in that select with a status-symbol prefix: a modified file shown as \"~ tracked_mod.txt\", a deleted file shown as \"- tracked_del.txt\", a brand-new untracked file shown as \"+ untracked_added.txt\", and a modified committed file whose name contains a space shown as \"~ spaced name.txt\". Verify all four options are present, with their full untruncated paths, by running an eval step whose expression is \"(() =\u003e { const opts = Array.from(document.querySelectorAll('select.diff-viewer-select option')).map(o =\u003e o.textContent.trim()); const has = (sym, name) =\u003e opts.some(t =\u003e t.startsWith(sym) \u0026\u0026 t.includes(name)); return has('+','untracked_added.txt') \u0026\u0026 has('~','tracked_mod.txt') \u0026\u0026 has('-','tracked_del.txt') \u0026\u0026 has('~','spaced name.txt') ? 'true' : 'false'; })()\" and expect the result \"true\". Two regression cases matter here: the untracked (added) file must be present with the \"+\" prefix, and the committed file with a space must appear as the full \"spaced name.txt\" (not truncated at the space to \"spaced\").",
   "version": 1,
   "steps": [
     {
       "action": "navigate",
-      "url": "/new?diff=working\u0026cwd=/tmp/shelley-lazycue-diff-fixture"
+      "url": "/new?diff=working\u0026cwd=/tmp/shelley-lazycue-diff-fixture-react"
     },
     {
       "action": "wait_visible",

…cue/.lazycue/react/7244604f6f935fb5.json …zycue/.lazycue/vue/b8bc987dd4b8a3a2.jsonui/lazycue/.lazycue/react/7244604f6f935fb5.json renamed to ui/lazycue/.lazycue/vue/b8bc987dd4b8a3a2.json ui/lazycue/.lazycue/react/7244604f6f935fb5.json renamed to ui/lazycue/.lazycue/vue/b8bc987dd4b8a3a2.json

@@ -1,11 +1,11 @@
 {
   "_README": "This file is managed by LazyCue (see shelley/lazycue). Do NOT edit by hand — it is the cached, machine-generated DSL for a self-healing browser test. To change behavior, edit the test description and re-run LazyCue.",
-  "description": "Navigate to /new?diff=working\u0026cwd=/tmp/shelley-lazycue-diff-fixture . This opens the git diff viewer for the working-tree changes of that repository. Wait for the file picker (a \u003cselect\u003e element with selector \"select.diff-viewer-select\") to be visible. The working tree has exactly four changed files, each appearing as an \u003coption\u003e in that select with a status-symbol prefix: a modified file shown as \"~ tracked_mod.txt\", a deleted file shown as \"- tracked_del.txt\", a brand-new untracked file shown as \"+ untracked_added.txt\", and a modified committed file whose name contains a space shown as \"~ spaced name.txt\". Verify all four options are present, with their full untruncated paths, by running an eval step whose expression is \"(() =\u003e { const opts = Array.from(document.querySelectorAll('select.diff-viewer-select option')).map(o =\u003e o.textContent.trim()); const has = (sym, name) =\u003e opts.some(t =\u003e t.startsWith(sym) \u0026\u0026 t.includes(name)); return has('+','untracked_added.txt') \u0026\u0026 has('~','tracked_mod.txt') \u0026\u0026 has('-','tracked_del.txt') \u0026\u0026 has('~','spaced name.txt') ? 'true' : 'false'; })()\" and expect the result \"true\". Two regression cases matter here: the untracked (added) file must be present with the \"+\" prefix, and the committed file with a space must appear as the full \"spaced name.txt\" (not truncated at the space to \"spaced\").",
+  "description": "Navigate to /new?diff=working\u0026cwd=/tmp/shelley-lazycue-diff-fixture-vue . This opens the git diff viewer for the working-tree changes of that repository. Wait for the file picker (a \u003cselect\u003e element with selector \"select.diff-viewer-select\") to be visible. The working tree has exactly four changed files, each appearing as an \u003coption\u003e in that select with a status-symbol prefix: a modified file shown as \"~ tracked_mod.txt\", a deleted file shown as \"- tracked_del.txt\", a brand-new untracked file shown as \"+ untracked_added.txt\", and a modified committed file whose name contains a space shown as \"~ spaced name.txt\". Verify all four options are present, with their full untruncated paths, by running an eval step whose expression is \"(() =\u003e { const opts = Array.from(document.querySelectorAll('select.diff-viewer-select option')).map(o =\u003e o.textContent.trim()); const has = (sym, name) =\u003e opts.some(t =\u003e t.startsWith(sym) \u0026\u0026 t.includes(name)); return has('+','untracked_added.txt') \u0026\u0026 has('~','tracked_mod.txt') \u0026\u0026 has('-','tracked_del.txt') \u0026\u0026 has('~','spaced name.txt') ? 'true' : 'false'; })()\" and expect the result \"true\". Two regression cases matter here: the untracked (added) file must be present with the \"+\" prefix, and the committed file with a space must appear as the full \"spaced name.txt\" (not truncated at the space to \"spaced\").",
   "version": 1,
   "steps": [
     {
       "action": "navigate",
-      "url": "/new?diff=working\u0026cwd=/tmp/shelley-lazycue-diff-fixture"
+      "url": "/new?diff=working\u0026cwd=/tmp/shelley-lazycue-diff-fixture-vue"
     },
     {
       "action": "wait_visible",