feat: Handle analyze retry with failure marker

When a previous analysis attempt fails and leaves a failure marker, the
retry mechanism now correctly identifies this state. It removes the
stale
input file, allowing the retry to proceed without a conflict error. This
ensures users can recover from analysis failures more gracefully.

server/tests/analyze_test.rs

@@ -272,6 +272,59 @@ async fn analyze_case_second_time_returns_409() {
     assert_eq!(second.status(), StatusCode::CONFLICT);
 }
 
+/// Bug regression (case c414cf52, 2026-05-03): a prior LLM run failed,
+/// leaving `analysis_input.json` AND `.analysis_failed.json` on disk.
+/// The user clicks "Erneut versuchen" — the handler must accept the
+/// retry instead of rejecting it as 409 Conflict ("Analyse läuft
+/// bereits"). The failure marker is the explicit "worker has given up"
+/// signal that legitimises overwriting the stale sentinel.
+#[tokio::test]
+async fn analyze_retry_after_failure_marker_overwrites_stale_input() {
+    let (cfg, settings) = cfg_llm("retry-after-fail");
+    let case_id = "11111111-1111-1111-1111-111111111111";
+    let case_dir = seed_case(&cfg.data_path, "dr_a", case_id);
+    seed_recording(&case_dir, "2026-04-15T10-00-00Z", Some("frischer Text"));
+
+    // Simulate the post-failure on-disk state: stale input from the
+    // attempt the worker gave up on, plus the matching failure marker.
+    std::fs::write(
+        case_dir.join(ANALYSIS_INPUT_FILE),
+        r#"{"last_recording_mtime":"2026-04-15T10:00:00Z","recordings":[{"recorded_at":"2026-04-15T10:00:00Z","text":"alter Text"}],"backend_id":""}"#,
+    )
+    .unwrap();
+    std::fs::write(
+        case_dir.join(".analysis_failed.json"),
+        r#"{"last_recording_mtime":"2026-04-15T10:00:00Z","reason":"llm: connect timeout","failed_at":"2026-04-15T10:05:00Z"}"#,
+    )
+    .unwrap();
+
+    let (app, store) = doctate_server::create_router_and_session_store_with_settings(cfg, settings);
+    let (cookie, csrf) = login_with_csrf(&app, &store, "dr_a", "s").await;
+
+    let resp = app
+        .oneshot(csrf_form_post(
+            paths::case_analyze(case_id),
+            &cookie,
+            &csrf,
+            "",
+        ))
+        .await
+        .unwrap();
+    assert_eq!(
+        resp.status(),
+        StatusCode::SEE_OTHER,
+        "retry with failure marker present must succeed, not 409"
+    );
+
+    // Input was rewritten with the fresh transcript — the stale "alter Text"
+    // must be gone.
+    let raw = std::fs::read_to_string(case_dir.join(ANALYSIS_INPUT_FILE)).unwrap();
+    let parsed: Value = serde_json::from_str(&raw).unwrap();
+    let recs = parsed["recordings"].as_array().unwrap();
+    assert_eq!(recs.len(), 1);
+    assert_eq!(recs[0]["text"], "frischer Text");
+}
+
 #[tokio::test]
 async fn analyze_case_skips_blank_transcript_from_recordings() {
     let (cfg, settings) = cfg_llm("i");

server/tests/case_page_test.rs

@@ -116,6 +116,9 @@ async fn case_page_shows_analyze_button_when_transcribed_without_document() {
 /// and the auto-trigger refuses to retry as long as the marker matches the
 /// current input. The case page must therefore surface a recovery banner
 /// that exposes the reason and a retry form, otherwise the user is stuck.
+///
+/// Doctor variant: only the default-backend "Erneut versuchen" button is
+/// shown; per-backend choice is admin-only (covered by the sibling test).
 #[tokio::test]
 async fn case_page_shows_failure_banner_with_retry_when_marker_present() {
     let (cfg, settings) = TestConfig::new()
@@ -173,8 +176,12 @@ async fn case_page_shows_failure_banner_with_retry_when_marker_present() {
         "retry form must POST to the analyze endpoint"
     );
     assert!(
-        body.contains("Erneut mit "),
-        "retry button label missing (expected 'Erneut mit <backend>')"
+        body.contains(">Erneut versuchen</button>"),
+        "default retry button missing (expected 'Erneut versuchen')"
+    );
+    assert!(
+        !body.contains("Erneut mit "),
+        "per-backend retry buttons must not be shown to non-admins"
     );
     assert!(
         !body.contains("Wird analysiert"),
@@ -182,6 +189,57 @@ async fn case_page_shows_failure_banner_with_retry_when_marker_present() {
     );
 }
 
+/// Admin variant of the failure-banner test: in addition to the default
+/// "Erneut versuchen" button shown to every user, an admin sees one
+/// "Erneut mit <backend>" button per configured backend, letting them
+/// re-analyse with a different model when one is misbehaving. Pins the
+/// `{% if is_admin %}` gate in `case_page.html` so a future refactor
+/// can't silently expose backend choice to all users (matches the
+/// `analyze` handler's 403 guard) or remove it from admins.
+#[tokio::test]
+async fn case_page_failure_banner_admin_can_choose_backend() {
+    let (cfg, settings) = TestConfig::new()
+        .with_label("cp-fail-banner-admin")
+        .with_user(test_admin("dr_a"))
+        .with_llm("http://unused")
+        .build_pair();
+    let case_id = "11111111-1111-1111-1111-111111111111";
+    let case_dir = seed_case(&cfg.data_path, "dr_a", case_id);
+    seed_recording(
+        &case_dir,
+        "2026-04-15T10-00-00Z",
+        Some("transkribierter Text"),
+    );
+    std::fs::write(
+        case_dir.join(".analysis_failed.json"),
+        r#"{"last_recording_mtime":"2026-04-15T10:00:00Z","reason":"llm: connect timeout","failed_at":"2026-04-15T10:05:00Z"}"#,
+    )
+    .unwrap();
+
+    let app = doctate_server::create_router_with_settings(cfg, settings);
+    let cookie = common::login(&app, "dr_a", "s").await;
+
+    let resp = app
+        .oneshot(get_with_cookie(paths::case_detail(case_id), &cookie))
+        .await
+        .unwrap();
+    assert_eq!(resp.status(), StatusCode::OK);
+    let body = body_string(resp).await;
+
+    assert!(
+        body.contains(r#"class="failure-banner""#),
+        "failure-banner div missing for admin"
+    );
+    assert!(
+        body.contains(">Erneut versuchen</button>"),
+        "default retry button must remain visible for admin too"
+    );
+    assert!(
+        body.contains("Erneut mit "),
+        "admin must see at least one 'Erneut mit <backend>' button"
+    );
+}
+
 #[tokio::test]
 #[ignore = "post-refactor any_backend_available() reads IONOS_API_KEY which TestConfig pre-sets; cannot be unset for one test in a shared process"]
 async fn case_page_shows_llm_missing_hint_without_llm() {