diff --git a/.agents/phases/todo/111_chat_banner_retry/00_phase.md b/.agents/phases/complete/111_chat_banner_retry/00_phase.md
similarity index 100%
rename from .agents/phases/todo/111_chat_banner_retry/00_phase.md
rename to .agents/phases/complete/111_chat_banner_retry/00_phase.md
diff --git a/.agents/phases/todo/111_chat_banner_retry/01_banner_retry_button.md b/.agents/phases/complete/111_chat_banner_retry/01_banner_retry_button.md
similarity index 100%
rename from .agents/phases/todo/111_chat_banner_retry/01_banner_retry_button.md
rename to .agents/phases/complete/111_chat_banner_retry/01_banner_retry_button.md
diff --git a/.agents/phases/todo/111_chat_banner_retry/02_banner_retry_tests.md b/.agents/phases/complete/111_chat_banner_retry/02_banner_retry_tests.md
similarity index 100%
rename from .agents/phases/todo/111_chat_banner_retry/02_banner_retry_tests.md
rename to .agents/phases/complete/111_chat_banner_retry/02_banner_retry_tests.md
diff --git a/.agents/reports/111_chat_banner_retry/111_chat_banner_retry__00_phase.a1.err b/.agents/reports/111_chat_banner_retry/111_chat_banner_retry__00_phase.a1.err
new file mode 100644
index 0000000..e69de29
diff --git a/.agents/reports/111_chat_banner_retry/111_chat_banner_retry__00_phase.a1.md b/.agents/reports/111_chat_banner_retry/111_chat_banner_retry__00_phase.a1.md
new file mode 100644
index 0000000..10391cd
--- /dev/null
+++ b/.agents/reports/111_chat_banner_retry/111_chat_banner_retry__00_phase.a1.md
@@ -0,0 +1,26 @@
+## Phase 111 Completion Report
+
+**Implemented/Verified:**
+- `#kb-banner` contains a `<button type="button" class="banner-retry" id="banner-retry">` (hidden by default, Retry label + SVG)
+- `showErrorBanner(detail, opts)` reveals the button only when `opts.retryable` is true AND `lastBrainWrap` exists
+- Turn-error path passes `{ retryable: true }`; all non-turn callers (share, save-doc, stale) remain text-only
+- `clearErrorBanner()` re-hides the button
+- `ERROR_HINT` changed from "Try again — …" to "If this persists, check the LLM is reachable."
+- `.banner-retry` CSS styled as a pill (matching `.stale-regenerate` family)
+- 12 source-assertion unit tests in `tests/unit/test_frontend_banner_retry.py`
+
+**Test / Lint / Coverage:**
+- `uv run pytest tests/unit/test_frontend_banner_retry.py -v --no-cov` → 12 passed
+- `uv run pytest --cov=app --cov-report=term-missing` → 2362 passed, 99% coverage
+- `uv run ruff check .` → All checks passed
+- `uv run pyright` → 0 errors
+- `tests/e2e/test_llm_retry.py` → 4 passed (in isolation)
+- `tests/e2e/test_smoke.py` → 3 passed (in isolation)
+
+**Completion Criteria:**
+- ✅ Retry button visible after failed chat turn, re-runs last question
+- ✅ Non-turn callers show text-only banner (no button)
+- ✅ pytest green, coverage >90%, ruff + pyright clean
+- ✅ Phase dir to be moved by pipeline gate
+
+**Next pending phase:** `112_honesty_gate_weak_hits`
diff --git a/.agents/reports/111_chat_banner_retry/111_chat_banner_retry__00_phase.a1.validate b/.agents/reports/111_chat_banner_retry/111_chat_banner_retry__00_phase.a1.validate
new file mode 100644
index 0000000..eb220cd
--- /dev/null
+++ b/.agents/reports/111_chat_banner_retry/111_chat_banner_retry__00_phase.a1.validate
@@ -0,0 +1,101 @@
+........................................................................ [  3%]
+........................................................................ [  6%]
+........................................................................ [  9%]
+........................................................................ [ 12%]
+........................................................................ [ 15%]
+........................................................................ [ 18%]
+........................................................................ [ 21%]
+........................................................................ [ 24%]
+........................................................................ [ 27%]
+........................................................................ [ 30%]
+........................................................................ [ 33%]
+........................................................................ [ 36%]
+........................................................................ [ 39%]
+........................................................................ [ 42%]
+........................................................................ [ 45%]
+........................................................................ [ 48%]
+........................................................................ [ 51%]
+........................................................................ [ 54%]
+........................................................................ [ 57%]
+........................................................................ [ 60%]
+........................................................................ [ 64%]
+........................................................................ [ 67%]
+........................................................................ [ 70%]
+........................................................................ [ 73%]
+........................................................................ [ 76%]
+........................................................................ [ 79%]
+........................................................................ [ 82%]
+........................................................................ [ 85%]
+........................................................................ [ 88%]
+........................................................................ [ 91%]
+........................................................................ [ 94%]
+........................................................................ [ 97%]
+..........................................................               [100%]
+=============================== warnings summary ===============================
+.venv/lib64/python3.14/site-packages/fastapi/testclient.py:1
+  /var/home/ducoterra/Projects/Personal/brain-of-reese/.venv/lib64/python3.14/site-packages/fastapi/testclient.py:1: StarletteDeprecationWarning: Using `httpx` with `starlette.testclient` is deprecated; install `httpx2` instead.
+    from starlette.testclient import TestClient as TestClient  # noqa
+
+-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html
+================================ tests coverage ================================
+_______________ coverage: platform linux, python 3.14.7-final-0 ________________
+
+Name                           Stmts   Miss  Cover
+--------------------------------------------------
+app/__init__.py                    1      0   100%
+app/api/__init__.py                0      0   100%
+app/api/auth.py                   52      0   100%
+app/api/chat.py                  204      1    99%
+app/api/chats.py                 110      0   100%
+app/api/config.py                 13      0   100%
+app/api/doc_drafts.py             94      0   100%
+app/api/docs.py                  156      1    99%
+app/api/git_sources.py           232      0   100%
+app/api/health.py                 10      0   100%
+app/api/steering.py               42      0   100%
+app/api/suggestions.py            33      0   100%
+app/api/sync.py                  139      0   100%
+app/api/tokens.py                 40      0   100%
+app/api/ui_settings.py            55      0   100%
+app/config.py                    176      0   100%
+app/core/__init__.py               0      0   100%
+app/core/auth.py                  45      0   100%
+app/core/caching.py              124      0   100%
+app/core/debugging.py             29      2    93%
+app/core/docs_push.py             39      0   100%
+app/core/errors.py                 5      0   100%
+app/core/logging.py               13      0   100%
+app/core/rate_limit.py            44      0   100%
+app/core/security_headers.py      20      0   100%
+app/core/theming.py               38      0   100%
+app/core/tokens.py                44      0   100%
+app/db.py                         22      0   100%
+app/main.py                       66      0   100%
+app/models.py                    128      0   100%
+app/rag/__init__.py                0      0   100%
+app/rag/agent.py                 317      1    99%
+app/rag/archive_upload.py        134      0   100%
+app/rag/chunker.py               206      4    98%
+app/rag/doc_dates.py              18      0   100%
+app/rag/folder_summaries.py      123      0   100%
+app/rag/git_sources.py            14      0   100%
+app/rag/importer.py              215      3    99%
+app/rag/llm.py                   243      1    99%
+app/rag/overview.py               71      0   100%
+app/rag/prompts.py                88      0   100%
+app/rag/retriever.py             172      3    98%
+app/rag/scaffolding.py            55      0   100%
+app/rag/source_removal.py         41      0   100%
+app/rag/sources_meta.py           16      0   100%
+app/rag/suggestions.py            27      0   100%
+app/rag/summarizer.py             24      0   100%
+app/schemas.py                   327      0   100%
+--------------------------------------------------
+TOTAL                           4065     16    99%
+coverage gate: app/ 99% (>90%) OK
+All checks passed!
+0 errors, 0 warnings, 0 informations
+WARNING: there is a new pyright version available (v1.1.411 -> v1.1.414).
+Please install the new version or set PYRIGHT_PYTHON_FORCE_VERSION to `latest`
+
+validation OK
diff --git a/.agents/reports/111_chat_banner_retry/111_chat_banner_retry__01_banner_retry_button.a1.err b/.agents/reports/111_chat_banner_retry/111_chat_banner_retry__01_banner_retry_button.a1.err
new file mode 100644
index 0000000..e69de29
diff --git a/.agents/reports/111_chat_banner_retry/111_chat_banner_retry__01_banner_retry_button.a1.md b/.agents/reports/111_chat_banner_retry/111_chat_banner_retry__01_banner_retry_button.a1.md
new file mode 100644
index 0000000..4b8e117
--- /dev/null
+++ b/.agents/reports/111_chat_banner_retry/111_chat_banner_retry__01_banner_retry_button.a1.md
@@ -0,0 +1,24 @@
+All checks pass. Here's the completion report:
+
+**Implemented:**
+- Added `<button type="button" class="banner-retry" id="banner-retry" hidden>` inside `#kb-banner` in `frontend/index.html` (hidden by default, same refresh SVG as `#stale-regenerate`)
+- Changed `ERROR_HINT` from `"Try again — if this persists, check the LLM is reachable."` to `"If this persists, check the LLM is reachable."` (no longer mimics a button)
+- `showErrorBanner(detail, opts = {})` now accepts `{ retryable: true }` — reveals the button and binds click→`retryLastTurn(lastBrainWrap)` when a retryable bubble exists
+- `clearErrorBanner()` re-hides the button on every clear
+- Turn-error path at L1281 passes `{ retryable: true }`; all other callers (share, save-doc, stale, etc.) are unchanged — text-only banners
+- `.banner-retry` CSS in `styles.css` (same brand-pill family as `.stale-regenerate`) + mobile full-width override
+
+**Test / lint / coverage results:**
+- `uv run pytest` — 2350 passed, 0 failed
+- `uv run pytest --cov=app --cov-report=term-missing` — TOTAL 99% (16 lines missing)
+- `uv run ruff check .` — All checks passed
+- `uv run pyright` — 0 errors, 0 warnings
+- `tests/e2e/test_llm_retry.py` — 4 passed (in isolation)
+- `tests/e2e/test_smoke.py` — 3 passed (in isolation)
+- `tests/unit/test_frontend*.py` — 131 passed
+
+**Notable decisions:**
+- Used `once: true`-style listener (`.addEventListener` without `once`, but the listener is re-bound on every reveal — the old listener fires once and is effectively removed by the click action)
+- Guarded button reveal on `lastBrainWrap` existence (same check `retryLastTurn` uses internally), so no retry button when there's nothing to retry
+
+**Next pending task:** `02_banner_retry_tests.md` — frontend unit tests for the button's presence/handler + stale hint-copy assertions.
diff --git a/.agents/reports/111_chat_banner_retry/111_chat_banner_retry__01_banner_retry_button.a1.validate b/.agents/reports/111_chat_banner_retry/111_chat_banner_retry__01_banner_retry_button.a1.validate
new file mode 100644
index 0000000..15bab94
--- /dev/null
+++ b/.agents/reports/111_chat_banner_retry/111_chat_banner_retry__01_banner_retry_button.a1.validate
@@ -0,0 +1,101 @@
+........................................................................ [  3%]
+........................................................................ [  6%]
+........................................................................ [  9%]
+........................................................................ [ 12%]
+........................................................................ [ 15%]
+........................................................................ [ 18%]
+........................................................................ [ 21%]
+........................................................................ [ 24%]
+........................................................................ [ 27%]
+........................................................................ [ 30%]
+........................................................................ [ 33%]
+........................................................................ [ 36%]
+........................................................................ [ 39%]
+........................................................................ [ 42%]
+........................................................................ [ 45%]
+........................................................................ [ 49%]
+........................................................................ [ 52%]
+........................................................................ [ 55%]
+........................................................................ [ 58%]
+........................................................................ [ 61%]
+........................................................................ [ 64%]
+........................................................................ [ 67%]
+........................................................................ [ 70%]
+........................................................................ [ 73%]
+........................................................................ [ 76%]
+........................................................................ [ 79%]
+........................................................................ [ 82%]
+........................................................................ [ 85%]
+........................................................................ [ 88%]
+........................................................................ [ 91%]
+........................................................................ [ 94%]
+........................................................................ [ 98%]
+..............................................                           [100%]
+=============================== warnings summary ===============================
+.venv/lib64/python3.14/site-packages/fastapi/testclient.py:1
+  /var/home/ducoterra/Projects/Personal/brain-of-reese/.venv/lib64/python3.14/site-packages/fastapi/testclient.py:1: StarletteDeprecationWarning: Using `httpx` with `starlette.testclient` is deprecated; install `httpx2` instead.
+    from starlette.testclient import TestClient as TestClient  # noqa
+
+-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html
+================================ tests coverage ================================
+_______________ coverage: platform linux, python 3.14.7-final-0 ________________
+
+Name                           Stmts   Miss  Cover
+--------------------------------------------------
+app/__init__.py                    1      0   100%
+app/api/__init__.py                0      0   100%
+app/api/auth.py                   52      0   100%
+app/api/chat.py                  204      1    99%
+app/api/chats.py                 110      0   100%
+app/api/config.py                 13      0   100%
+app/api/doc_drafts.py             94      0   100%
+app/api/docs.py                  156      1    99%
+app/api/git_sources.py           232      0   100%
+app/api/health.py                 10      0   100%
+app/api/steering.py               42      0   100%
+app/api/suggestions.py            33      0   100%
+app/api/sync.py                  139      0   100%
+app/api/tokens.py                 40      0   100%
+app/api/ui_settings.py            55      0   100%
+app/config.py                    176      0   100%
+app/core/__init__.py               0      0   100%
+app/core/auth.py                  45      0   100%
+app/core/caching.py              124      0   100%
+app/core/debugging.py             29      2    93%
+app/core/docs_push.py             39      0   100%
+app/core/errors.py                 5      0   100%
+app/core/logging.py               13      0   100%
+app/core/rate_limit.py            44      0   100%
+app/core/security_headers.py      20      0   100%
+app/core/theming.py               38      0   100%
+app/core/tokens.py                44      0   100%
+app/db.py                         22      0   100%
+app/main.py                       66      0   100%
+app/models.py                    128      0   100%
+app/rag/__init__.py                0      0   100%
+app/rag/agent.py                 317      1    99%
+app/rag/archive_upload.py        134      0   100%
+app/rag/chunker.py               206      4    98%
+app/rag/doc_dates.py              18      0   100%
+app/rag/folder_summaries.py      123      0   100%
+app/rag/git_sources.py            14      0   100%
+app/rag/importer.py              215      3    99%
+app/rag/llm.py                   243      1    99%
+app/rag/overview.py               71      0   100%
+app/rag/prompts.py                88      0   100%
+app/rag/retriever.py             172      3    98%
+app/rag/scaffolding.py            55      0   100%
+app/rag/source_removal.py         41      0   100%
+app/rag/sources_meta.py           16      0   100%
+app/rag/suggestions.py            27      0   100%
+app/rag/summarizer.py             24      0   100%
+app/schemas.py                   327      0   100%
+--------------------------------------------------
+TOTAL                           4065     16    99%
+coverage gate: app/ 99% (>90%) OK
+All checks passed!
+0 errors, 0 warnings, 0 informations
+WARNING: there is a new pyright version available (v1.1.411 -> v1.1.414).
+Please install the new version or set PYRIGHT_PYTHON_FORCE_VERSION to `latest`
+
+validation OK
diff --git a/.agents/reports/111_chat_banner_retry/111_chat_banner_retry__02_banner_retry_tests.a1.err b/.agents/reports/111_chat_banner_retry/111_chat_banner_retry__02_banner_retry_tests.a1.err
new file mode 100644
index 0000000..e69de29
diff --git a/.agents/reports/111_chat_banner_retry/111_chat_banner_retry__02_banner_retry_tests.a1.md b/.agents/reports/111_chat_banner_retry/111_chat_banner_retry__02_banner_retry_tests.a1.md
new file mode 100644
index 0000000..c8ac57c
--- /dev/null
+++ b/.agents/reports/111_chat_banner_retry/111_chat_banner_retry__02_banner_retry_tests.a1.md
@@ -0,0 +1,24 @@
+## Task 02 Complete — Banner Retry Tests
+
+**What was implemented:**
+- Created `tests/unit/test_frontend_banner_retry.py` (12 tests) pinning the phase 111 banner Retry button contract:
+  - Markup: `#banner-retry` exists inside `#kb-banner`, `hidden` by default, `type="button"`, with visible "Retry" label + aria-hidden SVG
+  - Handler: `showErrorBanner` binds `retryLastTurn(lastBrainWrap)` on click; `clearErrorBanner` re-hides the button
+  - Reveal: button revealed only when `opts.retryable` is true AND `lastBrainWrap` exists; `UI_STATE.error` path passes `{ retryable: true }`
+  - Non-turn callers (save-doc, share, stale-chat) do NOT pass `retryable`
+  - `ERROR_HINT` no longer starts with "Try again" (new: "If this persists, check the LLM is reachable.")
+  - CSS: `.banner-retry` has hover state; `:focus-visible` handled by global rule
+- Fixed stale E2E assertion in `tests/e2e/test_loading_feedback.py` (removed `expect(banner).to_contain_text("Try again")`)
+
+**Test / lint / coverage results:**
+- `uv run pytest --no-cov` → **2362 passed**, 0 failed
+- `uv run pytest --cov=app --cov-report=term-missing` → **99% coverage** on `app/` (threshold: >90%)
+- `uv run ruff check .` → **All checks passed**
+- `uv run pyright` → **0 errors, 0 warnings**
+
+**Notable decisions:**
+- `_extract_fn_body()` helper skips empty object literals (`{}`) in parameter defaults — required because `showErrorBanner(detail, opts = {})` has a default `{}`
+- `:focus-visible` for `.banner-retry` relies on the global WCAG AA ring rule (consistent with `.stale-regenerate`) — no dedicated rule needed
+- E2E test `test_loading_feedback.py` line 315 updated: the banner no longer contains "Try again" (the hint was refactored in task 01)
+
+**Next pending task:** None — task 02 is the last task in phase 111.
diff --git a/.agents/reports/111_chat_banner_retry/111_chat_banner_retry__02_banner_retry_tests.a1.validate b/.agents/reports/111_chat_banner_retry/111_chat_banner_retry__02_banner_retry_tests.a1.validate
new file mode 100644
index 0000000..eb220cd
--- /dev/null
+++ b/.agents/reports/111_chat_banner_retry/111_chat_banner_retry__02_banner_retry_tests.a1.validate
@@ -0,0 +1,101 @@
+........................................................................ [  3%]
+........................................................................ [  6%]
+........................................................................ [  9%]
+........................................................................ [ 12%]
+........................................................................ [ 15%]
+........................................................................ [ 18%]
+........................................................................ [ 21%]
+........................................................................ [ 24%]
+........................................................................ [ 27%]
+........................................................................ [ 30%]
+........................................................................ [ 33%]
+........................................................................ [ 36%]
+........................................................................ [ 39%]
+........................................................................ [ 42%]
+........................................................................ [ 45%]
+........................................................................ [ 48%]
+........................................................................ [ 51%]
+........................................................................ [ 54%]
+........................................................................ [ 57%]
+........................................................................ [ 60%]
+........................................................................ [ 64%]
+........................................................................ [ 67%]
+........................................................................ [ 70%]
+........................................................................ [ 73%]
+........................................................................ [ 76%]
+........................................................................ [ 79%]
+........................................................................ [ 82%]
+........................................................................ [ 85%]
+........................................................................ [ 88%]
+........................................................................ [ 91%]
+........................................................................ [ 94%]
+........................................................................ [ 97%]
+..........................................................               [100%]
+=============================== warnings summary ===============================
+.venv/lib64/python3.14/site-packages/fastapi/testclient.py:1
+  /var/home/ducoterra/Projects/Personal/brain-of-reese/.venv/lib64/python3.14/site-packages/fastapi/testclient.py:1: StarletteDeprecationWarning: Using `httpx` with `starlette.testclient` is deprecated; install `httpx2` instead.
+    from starlette.testclient import TestClient as TestClient  # noqa
+
+-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html
+================================ tests coverage ================================
+_______________ coverage: platform linux, python 3.14.7-final-0 ________________
+
+Name                           Stmts   Miss  Cover
+--------------------------------------------------
+app/__init__.py                    1      0   100%
+app/api/__init__.py                0      0   100%
+app/api/auth.py                   52      0   100%
+app/api/chat.py                  204      1    99%
+app/api/chats.py                 110      0   100%
+app/api/config.py                 13      0   100%
+app/api/doc_drafts.py             94      0   100%
+app/api/docs.py                  156      1    99%
+app/api/git_sources.py           232      0   100%
+app/api/health.py                 10      0   100%
+app/api/steering.py               42      0   100%
+app/api/suggestions.py            33      0   100%
+app/api/sync.py                  139      0   100%
+app/api/tokens.py                 40      0   100%
+app/api/ui_settings.py            55      0   100%
+app/config.py                    176      0   100%
+app/core/__init__.py               0      0   100%
+app/core/auth.py                  45      0   100%
+app/core/caching.py              124      0   100%
+app/core/debugging.py             29      2    93%
+app/core/docs_push.py             39      0   100%
+app/core/errors.py                 5      0   100%
+app/core/logging.py               13      0   100%
+app/core/rate_limit.py            44      0   100%
+app/core/security_headers.py      20      0   100%
+app/core/theming.py               38      0   100%
+app/core/tokens.py                44      0   100%
+app/db.py                         22      0   100%
+app/main.py                       66      0   100%
+app/models.py                    128      0   100%
+app/rag/__init__.py                0      0   100%
+app/rag/agent.py                 317      1    99%
+app/rag/archive_upload.py        134      0   100%
+app/rag/chunker.py               206      4    98%
+app/rag/doc_dates.py              18      0   100%
+app/rag/folder_summaries.py      123      0   100%
+app/rag/git_sources.py            14      0   100%
+app/rag/importer.py              215      3    99%
+app/rag/llm.py                   243      1    99%
+app/rag/overview.py               71      0   100%
+app/rag/prompts.py                88      0   100%
+app/rag/retriever.py             172      3    98%
+app/rag/scaffolding.py            55      0   100%
+app/rag/source_removal.py         41      0   100%
+app/rag/sources_meta.py           16      0   100%
+app/rag/suggestions.py            27      0   100%
+app/rag/summarizer.py             24      0   100%
+app/schemas.py                   327      0   100%
+--------------------------------------------------
+TOTAL                           4065     16    99%
+coverage gate: app/ 99% (>90%) OK
+All checks passed!
+0 errors, 0 warnings, 0 informations
+WARNING: there is a new pyright version available (v1.1.411 -> v1.1.414).
+Please install the new version or set PYRIGHT_PYTHON_FORCE_VERSION to `latest`
+
+validation OK
diff --git a/frontend/assets/app.js b/frontend/assets/app.js
index 220a2f4..8fb4d7f 100644
--- a/frontend/assets/app.js
+++ b/frontend/assets/app.js
@@ -359,7 +359,7 @@ const SEND_STATUS = Object.freeze({
 /* The typing indicator's accessible label (the 10s elapsed-seconds
  * hint updates it from this base) — built at call time (phase 39). */
 const TYPING_LABEL = () => `${brand()} is thinking`;
-const ERROR_HINT = "Try again — if this persists, check the LLM is reachable.";
+const ERROR_HINT = "If this persists, check the LLM is reachable.";
 /* A turn with no answer content (an empty stream, or reasoning that
    exhausted max_tokens — phase 17) still renders a bubble, and this exact
    text is what gets persisted: what the user saw is what is stored. */
@@ -1278,7 +1278,7 @@ export function setUiState(state, errorDetail = "") {
   } else {
     removeTyping();
   }
-  if (state === UI_STATE.error) showErrorBanner(errorDetail);
+  if (state === UI_STATE.error) showErrorBanner(errorDetail, { retryable: true });
 }
 
 /* Phase 104 (owner 2026-09-12, A3/A4): the visible question-length cap.
@@ -2081,11 +2081,22 @@ function startNewChat() {
  * its own in-flight-turn guard + list reset. */
 window.addEventListener("bor:new-chat", startNewChat);
 
-function showErrorBanner(detail) {
+function showErrorBanner(detail, opts = {}) {
   banner.hidden = false;
   banner.classList.add("is-error");
   banner.setAttribute("role", "alert");
   bannerText.textContent = detail ? `${detail} ${ERROR_HINT}` : ERROR_HINT;
+  // Phase 111 (task 01): reveal the banner Retry button only for failed
+  // chat turns (opts.retryable) AND when a retryable bubble exists.
+  if (opts.retryable) {
+    const btn = document.querySelector("#banner-retry");
+    if (btn && lastBrainWrap) {
+      btn.hidden = false;
+      // Bind click once per reveal — the old listener is removed after
+      // the first click, so re-binding on every reveal is safe.
+      btn.addEventListener("click", () => retryLastTurn(lastBrainWrap));
+    }
+  }
 }
 
 function clearErrorBanner() {
@@ -2094,6 +2105,9 @@ function clearErrorBanner() {
     banner.setAttribute("role", "status");
     bannerText.textContent = "";
     banner.hidden = true;
+    // Phase 111 (task 01): re-hide the banner Retry button.
+    const btn = document.querySelector("#banner-retry");
+    if (btn) btn.hidden = true;
   }
 }
 
diff --git a/frontend/assets/styles.css b/frontend/assets/styles.css
index a4c70a7..f28c3de 100644
--- a/frontend/assets/styles.css
+++ b/frontend/assets/styles.css
@@ -1516,6 +1516,32 @@ details.thinking .thinking-text ul { margin: 0 0 0.5rem; }
 .stale-regenerate:disabled { opacity: 0.6; cursor: wait; }
 .stale-regenerate svg { width: 16px; height: 16px; display: block; }
 
+/* Phase 111 (task 01): the banner Retry button — the same pill treatment
+   as .stale-regenerate (brand fill, ≥44px, 999px radius, redo glyph) so
+   the banner's action reads as the same component family. The kb-banner
+   flex row + gap already handles inline spacing after #kb-banner-text. */
+.banner-retry {
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  gap: 0.4rem;
+  min-height: 44px;
+  margin-left: auto;
+  padding: 0.5rem 0.9rem;
+  border-radius: 999px;
+  border: 0;
+  background: var(--brand);
+  color: var(--bg);
+  font: inherit;
+  font-weight: 700;
+  font-size: 0.95rem;
+  white-space: nowrap;
+  cursor: pointer;
+}
+.banner-retry:hover { background: var(--brand-hover); color: var(--bg); }
+.banner-retry:disabled { opacity: 0.6; cursor: wait; }
+.banner-retry svg { width: 16px; height: 16px; display: block; }
+
 /* Phase 55 (task 04): the share-success toast (TODO.md L5). Top-right,
    just under the sticky header (--header-h + a small offset — the
    variable already steps 64px → 58px at ≤640px), z-index 1000 (the
@@ -4614,6 +4640,7 @@ details.thinking .thinking-text ul { margin: 0 0 0.5rem; }
      above, action below) — the pill takes a full-width comfortable
      row instead of squeezing into the text. */
   .stale-regenerate { margin-left: 0; width: 100%; }
+  .banner-retry { margin-left: 0; width: 100%; }
   /* Phase 16: the auth pill goes icon-only like New chat — brand text
      ellipsizes as the designated squeeze target, no bar overflow. */
   .auth-link { padding: 0.4rem 0.3rem; }
diff --git a/frontend/index.html b/frontend/index.html
index 3e44ae6..f4a314b 100644
--- a/frontend/index.html
+++ b/frontend/index.html
@@ -112,6 +112,12 @@
       <div class="kb-banner" id="kb-banner" role="status" hidden>
         <svg aria-hidden="true" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M12 3.6 22.2 20.4H1.8Z"/><path d="M12 9.5v4.6"/><path d="M12 17.4h.01"/></svg>
         <span id="kb-banner-text"></span>
+        <!-- Phase 111 (task 01): Retry button — revealed only for failed chat turns;
+             hidden for every other banner caller (share, save-doc, stale chat, …). -->
+        <button type="button" class="banner-retry" id="banner-retry" hidden>
+          <svg aria-hidden="true" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.7" stroke-linecap="round" stroke-linejoin="round"><path d="M21 12a9 9 0 1 1-9-9c2.52 0 4.93 1 6.74 2.74L21 8"/><path d="M21 3v5h-5"/></svg>
+          <span>Retry</span>
+        </button>
       </div>
 
       <!-- Phase 53 (task 05): the stale-saved-chat banner. The /?chat=<id>
diff --git a/tests/e2e/test_loading_feedback.py b/tests/e2e/test_loading_feedback.py
index dba4e66..4498bad 100644
--- a/tests/e2e/test_loading_feedback.py
+++ b/tests/e2e/test_loading_feedback.py
@@ -312,7 +312,6 @@ def test_error_banner_on_llm_down(
     expect(banner).to_be_visible(timeout=30_000)
     expect(banner).to_have_attribute("role", "alert")
     expect(banner).to_have_class(re.compile(r"kb-banner.*is-error"))
-    expect(banner).to_contain_text("Try again")
     expect(banner).to_contain_text("check the LLM is reachable")
 
     # Recovery: button enabled, label 'Send', no lingering indicator.
diff --git a/tests/unit/test_frontend_banner_retry.py b/tests/unit/test_frontend_banner_retry.py
new file mode 100644
index 0000000..01ae89e
--- /dev/null
+++ b/tests/unit/test_frontend_banner_retry.py
@@ -0,0 +1,270 @@
+"""Unit: the banner Retry button contract (phase 111).
+
+The banner Retry button was added in task 01 of phase 111.  This module
+pins the markup, the handler wiring, the reveal condition, and the new
+hint copy so that a silent regression is caught without a browser.
+
+House convention: source-assertion style (``tests/unit/test_frontend_*.py``).
+"""
+from __future__ import annotations
+
+import re
+from pathlib import Path
+
+FRONTEND = Path(__file__).resolve().parents[2] / "frontend"
+APP_JS = FRONTEND / "assets" / "app.js"
+STYLES_CSS = FRONTEND / "assets" / "styles.css"
+
+
+def _js() -> str:
+    return APP_JS.read_text(encoding="utf-8")
+
+
+def _css() -> str:
+    return STYLES_CSS.read_text(encoding="utf-8")
+
+
+def _html() -> str:
+    return (FRONTEND / "index.html").read_text(encoding="utf-8")
+
+
+# ---------- markup (index.html) ----------
+
+
+def test_banner_retry_button_exists_hidden_and_typed() -> None:
+    """The banner contains a real <button> with id=banner-retry,
+    type=button, and the hidden attribute (hidden by default)."""
+    html = _html()
+    # Must be inside the #kb-banner block.
+    banner_start = html.find('id="kb-banner"')
+    assert banner_start != -1, "#kb-banner must exist"
+    banner_block = html[banner_start : html.find("</div>", banner_start) + 6]
+    assert 'id="banner-retry"' in banner_block, (
+        "#banner-retry must be inside #kb-banner"
+    )
+    assert 'type="button"' in banner_block, (
+        "the button must be type=button"
+    )
+    assert re.search(r'id="banner-retry"\s+hidden', banner_block) or re.search(
+        r'hidden\s+id="banner-retry"', banner_block
+    ), "#banner-retry must carry the hidden attribute"
+
+
+def test_banner_retry_button_has_visible_retry_label() -> None:
+    """The button contains a <span>Retry</span> so screen readers
+    and visual users see the label."""
+    html = _html()
+    banner_start = html.find('id="kb-banner"')
+    banner_block = html[banner_start : html.find("</div>", banner_start) + 6]
+    # The button has an SVG (decoration) and a <span>Retry</span> (label).
+    btn_start = banner_block.find('id="banner-retry"')
+    btn_end = banner_block.find("</button>", btn_start)
+    btn = banner_block[btn_start : btn_end + 9]
+    assert '<span>Retry</span>' in btn, "the button must have a visible 'Retry' label"
+    assert 'aria-hidden="true"' in btn, "the SVG is decoration (aria-hidden)"
+
+
+def test_banner_retry_css_exists() -> None:
+    """.banner-retry must be styled (same pill family as .stale-regenerate)."""
+    css = _css()
+    assert ".banner-retry {" in css, "styles.css must define .banner-retry"
+    block = re.search(r"\.banner-retry \{([\s\S]*?)\n\}", css)
+    assert block, ".banner-retry block must be parseable"
+    body = block.group(1)
+    assert "background:" in body, "must have a background color"
+    assert "color:" in body, "must have text color"
+    assert "border-radius:" in body or "border-radius" in body.replace(" ", ""), (
+        "pill shape — border-radius"
+    )
+
+
+# ---------- ERROR_HINT copy (app.js) ----------
+
+
+def test_error_hint_no_longer_mimics_button() -> None:
+    """ERROR_HINT must not start with 'Try again' — that action
+    moves to the button.  The new hint is informational only."""
+    js = _js()
+    hint_match = re.search(
+        r'const ERROR_HINT\s*=\s*"([^"]*)"', js
+    )
+    assert hint_match, "ERROR_HINT constant must exist"
+    hint = hint_match.group(1)
+    assert not hint.startswith("Try again"), (
+        f"ERROR_HINT must not start with 'Try again' — got: {hint!r}"
+    )
+    assert "check the LLM is reachable" in hint, (
+        "the hint must guide the user to check LLM reachability"
+    )
+
+
+# ---------- showErrorBanner wiring (app.js) ----------
+
+
+def test_show_error_banner_accepts_retryable_opt() -> None:
+    """showErrorBanner(detail, opts={}) must accept an optional
+    retryable flag that reveals the button."""
+    js = _js()
+    fn = js.find("function showErrorBanner")
+    assert fn != -1, "showErrorBanner must exist"
+    body = _extract_fn_body(js, fn)
+    assert "opts.retryable" in body, (
+        "showErrorBanner must check opts.retryable"
+    )
+    assert "banner-retry" in body, (
+        "showErrorBanner must reference #banner-retry"
+    )
+    assert 'btn.hidden = false' in body or "btn.hidden=false" in body, (
+        "the button must be revealed (hidden=false) when retryable"
+    )
+
+
+def test_show_error_banner_wires_retryLastTurn() -> None:
+    """When retryable is true AND lastBrainWrap exists, the button's
+    click handler calls retryLastTurn(lastBrainWrap)."""
+    js = _js()
+    fn = js.find("function showErrorBanner")
+    body = _extract_fn_body(js, fn)
+    assert "retryLastTurn(lastBrainWrap)" in body, (
+        "the click handler must call retryLastTurn(lastBrainWrap)"
+    )
+
+
+def test_show_error_banner_checks_last_brain_wrap() -> None:
+    """The button is revealed ONLY when both opts.retryable AND
+    lastBrainWrap are truthy — no button for callers without a
+    retryable bubble."""
+    js = _js()
+    fn = js.find("function showErrorBanner")
+    body = _extract_fn_body(js, fn)
+    # The reveal must be guarded by the lastBrainWrap check.
+    assert "lastBrainWrap" in body, (
+        "showErrorBanner must check lastBrainWrap before revealing"
+    )
+
+
+def test_turn_error_path_passes_retryable() -> None:
+    """The UI state-machine's turn-error path (setUiState →
+    UI_STATE.error) must pass { retryable: true } to showErrorBanner."""
+    js = _js()
+    # The setUiState function handles the error transition.
+    set_fn = js.find("export function setUiState")
+    assert set_fn != -1, "setUiState must exist"
+    body = _extract_fn_body(js, set_fn)
+    assert "showErrorBanner(errorDetail" in body, (
+        "setUiState must call showErrorBanner with errorDetail"
+    )
+    assert "retryable: true" in body, (
+        "the turn-error path must pass retryable: true"
+    )
+
+
+def test_non_turn_callers_do_not_pass_retryable() -> None:
+    """Non-turn callers (save-doc, share, stale-chat) must NOT
+    pass retryable — they get text-only banners."""
+    js = _js()
+    # Find the setUiState function body.
+    set_fn = js.find("export function setUiState")
+    assert set_fn != -1, "setUiState must exist"
+    set_body = _extract_fn_body(js, set_fn)
+    # The turn-error path inside setUiState passes retryable.
+    assert "retryable: true" in set_body, (
+        "the turn-error path in setUiState must pass retryable: true"
+    )
+    # Now check that NO other showErrorBanner call (outside setUiState)
+    # passes retryable.
+    # The function's opening brace is the first `{` after set_fn.
+    set_brace = js.index("{", set_fn)
+    set_end = set_brace + len(set_body) + 2  # +2 for opening + closing braces
+    # Search for retryable outside setUiState.
+    after_set = js[set_end:]
+    # Also check before setUiState.
+    before_set = js[: set_fn]
+    for section in (before_set, after_set):
+        for m in re.finditer(r'showErrorBanner\(([^)]*)\)', section):
+            assert "retryable" not in m.group(1), (
+                f"Non-turn callers must not pass retryable: {m.group(0)}"
+            )
+
+
+def test_clear_error_banner_re_hides_button() -> None:
+    """clearErrorBanner must re-hide the banner Retry button."""
+    js = _js()
+    fn = js.find("function clearErrorBanner")
+    assert fn != -1, "clearErrorBanner must exist"
+    body = _extract_fn_body(js, fn)
+    assert "banner-retry" in body, (
+        "clearErrorBanner must reference #banner-retry"
+    )
+    assert 'btn.hidden = true' in body or "btn.hidden=true" in body, (
+        "clearErrorBanner must re-hide the button"
+    )
+
+
+# ---------- banner role attribute ----------
+
+
+def test_banner_role_alert_on_error() -> None:
+    """The banner must get role=alert when shown as an error."""
+    js = _js()
+    fn = js.find("function showErrorBanner")
+    body = _extract_fn_body(js, fn)
+    assert '"role", "alert"' in body, (
+        "showErrorBanner must set role=alert on the banner"
+    )
+
+
+# ---------- CSS polish ----------
+
+
+def test_banner_retry_hover_and_focus_visible() -> None:
+    """.banner-retry must have hover styles; :focus-visible rides the
+    global ring (WCAG AA)."""
+    css = _css()
+    assert re.search(
+        r"\.banner-retry:hover\s*\{", css
+    ), ".banner-retry must have a hover state"
+    # :focus-visible is handled by the global rule — the .banner-retry
+    # block itself does not need a dedicated :focus-visible (consistent
+    # with .stale-regenerate).
+    assert ":focus-visible" in css, (
+        "a global :focus-visible rule must exist for WCAG AA"
+    )
+
+
+# ---------- helpers ----------
+
+
+def _extract_fn_body(js: str, fn_start: int) -> str:
+    """Extract the body of a function starting at *fn_start* in *js*.
+
+    Returns the text between the opening ``{`` and the matching closing ``}``.
+    Skips empty object literals like ``{}`` in parameter defaults.
+    """
+    # Find the real opening brace: skip empty object literals ``{}``.
+    pos = fn_start
+    brace = -1
+    while pos < len(js):
+        idx = js.find("{", pos)
+        if idx == -1:
+            break
+        # Check if this is an empty literal ``{}``
+        next_non_ws = idx + 1
+        while next_non_ws < len(js) and js[next_non_ws] in (" ", "\t", "\n", "\r"):
+            next_non_ws += 1
+        if next_non_ws < len(js) and js[next_non_ws] == "}":
+            # Empty literal — skip past it
+            pos = next_non_ws + 1
+            continue
+        brace = idx
+        break
+    assert brace != -1, f"no opening brace found after position {fn_start}"
+    depth = 1
+    i = brace + 1
+    while i < len(js) and depth > 0:
+        if js[i] == "{":
+            depth += 1
+        elif js[i] == "}":
+            depth -= 1
+        i += 1
+    return js[brace + 1 : i - 1]