diff --git a/Agent.md b/Agent.md
index 2530a48a..fdfc00dd 100644
--- a/Agent.md
+++ b/Agent.md
@@ -118,7 +118,7 @@ Community needs voiced in HN agent-UI discussions map directly to EMRG's design:
 pkill -f "emrg.server"; rm -f ~/.emrg/emrgd.token; python -m emrg
 ```
 
-Python: `uv run pytest tests/ -v` (988) — import check: `uv run python -c "from emrg.client.app import run_client"`
+Python: `uv run pytest tests/ -v` (989) — import check: `uv run python -c "from emrg.client.app import run_client"`
 GUI: `cd emrg/gui && npm test` (256: 45 daemon_client + 19 conn-manager + 22 app-commands + 127 renderer smoke + 15 i18n + 8 integration + 3 commands + 8 build-config + 7 gui-state + 2 tool-group) — syntax: `node --check main.js preload.js daemon_client.js renderer/js/*.js`
 CI: `uv run pytest` (ubuntu + **windows-2025 matrix** — Windows pytest 回归在 PR CI 即失败，v0.2.29 教训 #725) + GUI tests + **actionlint workflow lint** (`rhysd/actionlint@v1.7.12` gate, #444 — workflow 解析错误在 PR CI 即失败，如 `if:` secrets 上下文)
 Re-trigger: `scripts/re-trigger-ci.sh [branch]` (workflow_dispatch, #527 — 替代空 commit 重触发：Actions outage 会整段丢弃 push 事件，dispatch 走 API 路径不受影响)
diff --git a/emrg/gui/main.js b/emrg/gui/main.js
index 56a62a0d..d2b27af3 100644
--- a/emrg/gui/main.js
+++ b/emrg/gui/main.js
@@ -285,6 +285,7 @@ vision = false
         model: pong?.model || "",
         evolution_count: pong?.evolution_count ?? 0, // G19：init 透传演化计数（waitForPong 已消耗 pong）
         current_version: pong?.current_version || "", // rant 18:30:57：安装版本（GUI 对比显示升级横幅）
+        previous_version: pong?.previous_version || "", // rant 12:44:34：升级前版本（横幅 from→to）
         version: APP_VERSION, // WorkBuddy P3：版本号随 package.json 走（此前 renderer 硬编码 v0.2.7）
         sessions,
         open_sessions: openSessionsList(),
@@ -871,7 +872,7 @@ vision = false
         const sessions = await listSessions();
         sendToRenderer("sessions", { sessions });
         const pong = await waitForPong();
-        sendToRenderer("status", { connected: true, server_id: pong?.identity?.instance_id, model: pong?.model, current_version: pong?.current_version || "" });
+        sendToRenderer("status", { connected: true, server_id: pong?.identity?.instance_id, model: pong?.model, current_version: pong?.current_version || "", previous_version: pong?.previous_version || "" });
         logger.info("[gui] connManager recovery complete");
       } catch (e) {
         logger.warn(`[gui] post-recovery refresh failed: ${e.message}`);
@@ -1098,7 +1099,7 @@ vision = false
         const sessions = await listSessions();
         sendToRenderer("sessions", { sessions });
         const pong = await waitForPong();
-        sendToRenderer("status", { connected: true, server_id: pong?.identity?.instance_id, model: pong?.model, current_version: pong?.current_version || "" });
+        sendToRenderer("status", { connected: true, server_id: pong?.identity?.instance_id, model: pong?.model, current_version: pong?.current_version || "", previous_version: pong?.previous_version || "" });
       }
     }, delay);
   }
diff --git a/emrg/gui/renderer/js/app.js b/emrg/gui/renderer/js/app.js
index dd7a3191..cdaaf504 100644
--- a/emrg/gui/renderer/js/app.js
+++ b/emrg/gui/renderer/js/app.js
@@ -77,6 +77,7 @@ const App = (() => {
       state.model = init.model || "";
       state.version = init.version || "";
       state.currentVersion = init.current_version || ""; // rant 18:30:57：安装版本（升级横幅对比基准）
+      state.previousVersion = init.previous_version || ""; // rant 12:44:34：升级前版本（横幅 from→to）
       state.lastKnownVersion = state.currentVersion;
       state.evolutionCount = init.evolution_count ?? null;
       state.lastKnownEvolutionCount = state.evolutionCount;
@@ -1337,14 +1338,21 @@ const App = (() => {
     $("conn-banner").classList.add("hidden");
   }
 
-  // ── 升级完成横幅（rant 2026-08-20T18:30:57） ─────────────
-  function maybeShowUpgradeBanner(currentVersion) {
+  // ── 升级完成横幅（rant 2026-08-20T18:30:57 + 2026-08-21T12:44:34） ─────
+  function maybeShowUpgradeBanner(currentVersion, previousVersion) {
     if (!currentVersion) return; // 无版本数据（dev 运行）→ 不显示
     if (currentVersion === state.lastKnownVersion) return; // 版本未变
     const b = $("upgrade-banner");
     if (!b) return;
     const msg = $("upgrade-banner-msg");
-    if (msg) msg.textContent = _t("app.upgradeBannerMsg", { version: currentVersion });
+    if (msg) {
+      // rant 12:44:34：daemon 提供升级前版本 → 显示 "from → to"；否则回退旧文案
+      if (previousVersion && previousVersion !== currentVersion) {
+        msg.textContent = _t("app.upgradeBannerMsgFromTo", { from: previousVersion, to: currentVersion });
+      } else {
+        msg.textContent = _t("app.upgradeBannerMsg", { version: currentVersion });
+      }
+    }
     b.classList.remove("hidden");
     state.lastKnownVersion = currentVersion; // 已提示，防重复弹
   }
@@ -1574,7 +1582,9 @@ const App = (() => {
       if (data.model) state.model = data.model;
       state.evolutionCount = data.evolution_count ?? state.evolutionCount;
       // rant 18:30:57：pong 携带 current_version → 对比已知版本，变化则弹升级横幅
-      maybeShowUpgradeBanner(data.current_version || state.currentVersion);
+      // rant 12:44:34：同时携带 previous_version → 横幅显示 from → to
+      if (data.previous_version) state.previousVersion = data.previous_version;
+      maybeShowUpgradeBanner(data.current_version || state.currentVersion, state.previousVersion);
       updateModelSwitcher();
       updateGrowthCard();
       maybeShowEvolutionToast();
diff --git a/emrg/gui/renderer/js/i18n.js b/emrg/gui/renderer/js/i18n.js
index 783205d6..afb085a4 100644
--- a/emrg/gui/renderer/js/i18n.js
+++ b/emrg/gui/renderer/js/i18n.js
@@ -415,6 +415,7 @@ const I18N = (() => {
       "app.modelSwitchFailed": "切换模型失败了：{msg}",
       "app.modelListFailed": "读取模型列表失败了：{msg}",
       "app.upgradeBannerMsg": "EMRG 已升级到 {version}，重启后生效",
+      "app.upgradeBannerMsgFromTo": "EMRG 已从 {from} 升级到 {to}，重启后生效",
       "app.upgradeRestartFailed": "重启失败：{msg}",
       "app.upgradeRestartBtn": "重启生效",
       "app.unknownResult": "结果未知——连接中断",
@@ -826,6 +827,7 @@ const I18N = (() => {
       "app.modelSwitchFailed": "Failed to switch model: {msg}",
       "app.modelListFailed": "Failed to load models: {msg}",
       "app.upgradeBannerMsg": "EMRG upgraded to {version} — restart to apply",
+      "app.upgradeBannerMsgFromTo": "EMRG upgraded from {from} to {to} — restart to apply",
       "app.upgradeRestartFailed": "Restart failed: {msg}",
       "app.upgradeRestartBtn": "Restart to apply",
       "app.unknownResult": "Result unknown — connection lost",
diff --git a/emrg/gui/test/renderer.smoke.test.js b/emrg/gui/test/renderer.smoke.test.js
index b557a631..2663ae36 100644
--- a/emrg/gui/test/renderer.smoke.test.js
+++ b/emrg/gui/test/renderer.smoke.test.js
@@ -735,13 +735,14 @@ test("GCM rant Stage 2：演化增长 + 未认证 → GitHub 连接横幅出现
   assert.ok(toastBlock.includes("maybeShowGithubBanner()"), "演化增长应触发 GitHub 横幅检查");
 });
 
-test("rant 18:30:57：版本变化 → 升级横幅出现 + 重启按钮触发 restartDaemon（正反两态）", async () => {
-  // 正态：status current_version 与已知版本不同 → 横幅出现
+test("rant 18:30:57 + 12:44:34：版本变化 → 升级横幅（from→to）+ 重启按钮触发 restartDaemon（正反两态）", async () => {
+  // 正态：status current_version 与已知版本不同 → 横幅出现；有 previous_version → 显示 from→to
   const { ctx } = makeSandbox({
     init: async () => ({
       config_exists: true,
       api_key_configured: true,
       current_version: "0.2.58",
+      previous_version: "",
       sessions: [],
     }),
   });
@@ -749,13 +750,15 @@ test("rant 18:30:57：版本变化 → 升级横幅出现 + 重启按钮触发 r
   await vm.runInContext(`(function() {
     document.getElementById("upgrade-banner").classList.add("hidden");
     App.state.lastKnownVersion = "0.2.58";
-    App.handleEvent({ type: "status", data: { connected: true, current_version: "0.2.59" } });
+    App.handleEvent({ type: "status", data: { connected: true, current_version: "0.2.61", previous_version: "0.2.57" } });
   })()`, ctx);
   const visible = vm.runInContext(
     '!document.getElementById("upgrade-banner").classList.contains("hidden")',
     ctx
   );
   assert.strictEqual(visible, true, "版本变化 → 升级横幅应出现");
+  const bannerText = vm.runInContext('document.getElementById("upgrade-banner-msg").textContent', ctx);
+  assert.ok(bannerText.includes("0.2.57") && bannerText.includes("0.2.61"), `横幅应显示 from→to，实际 ${bannerText}`);
 
   // 负态：版本未变 → 横幅保持隐藏
   const { ctx: ctx2 } = makeSandbox({});
diff --git a/emrg/server/daemon.py b/emrg/server/daemon.py
index 15f97053..7e14499a 100644
--- a/emrg/server/daemon.py
+++ b/emrg/server/daemon.py
@@ -645,6 +645,21 @@ def _current_installed_version(self) -> str:
         except (OSError, ValueError):
             return ""
 
+    def _previous_installed_version(self) -> str:
+        """Pre-upgrade EMRG version from ~/.emrg/install/previous-version.txt.
+
+        Rant 2026-08-21T12:44:34: the upgrade agent writes the version it is
+        replacing into previous-version.txt before overwriting version.txt,
+        so the GUI banner can show "upgraded from X to Y" instead of only the
+        target version. Raw data only; "" when missing (dev/standalone or
+        first install).
+        """
+        try:
+            v = (Path.home() / ".emrg" / "install" / "previous-version.txt").read_text(encoding="utf-8").strip()
+            return v
+        except (OSError, ValueError):
+            return ""
+
     def _evolution_count(self) -> int:
         """Total completed evolution cycles across scheduler handlers + disk.
 
@@ -1421,6 +1436,9 @@ async def _process_message(
                 # 上次已知版本，发现变化 → 弹"已升级，重启生效"横幅。daemon 只回原始数据，
                 # 零判断逻辑（升级判断由 GUI 负责）。
                 "current_version": self._current_installed_version(),
+                # Rant 2026-08-21T12:44:34：并入升级前版本——GUI 横幅显示 "from → to"
+                # （升级 agent 在覆盖 version.txt 前写入 previous-version.txt）。
+                "previous_version": self._previous_installed_version(),
             })
             return
 
diff --git a/emrg/server/prompts/upgrade_prompt.j2 b/emrg/server/prompts/upgrade_prompt.j2
index fd39973f..4ac00cfd 100644
--- a/emrg/server/prompts/upgrade_prompt.j2
+++ b/emrg/server/prompts/upgrade_prompt.j2
@@ -44,6 +44,11 @@ release installer" means for this version.
   update or add — the target tag's pyproject.toml dependencies are the
   source of truth. Operate as needed (pip --target install/uninstall/update).
 - `{{ install_dir }}/version.txt` ← {{ target_tag }} (the version).
+- Before overwriting `version.txt`: if it already exists with a different
+  content, copy its current content to `{{ install_dir }}/previous-version.txt`
+  (rant 2026-08-21T12:44:34 — the GUI upgrade banner shows "from X to Y").
+  If `version.txt` did not exist (first install), delete any stale
+  `previous-version.txt`.
 - `{{ install_dir }}/bin/` launcher scripts (emrg/emrgd/emrg.cmd/emrgd.cmd
   etc.) — sync if the target tag changed them.
 - GUI as needed: whether `~/Applications/EMRG.app` is updated is YOUR call —
diff --git a/tests/test_daemon.py b/tests/test_daemon.py
index 0c8a2508..9412a546 100644
--- a/tests/test_daemon.py
+++ b/tests/test_daemon.py
@@ -1751,3 +1751,38 @@ def test_pong_includes_current_version(tmp_path, monkeypatch):
     frame = _last_frame(writer)
     assert frame["type"] == "pong"
     assert frame["current_version"] == "0.2.59"
+
+
+def test_pong_includes_previous_version(tmp_path, monkeypatch):
+    """Pong carries previous_version from ~/.emrg/install/previous-version.txt.
+
+    Rant 2026-08-21T12:44:34: the upgrade agent records the pre-upgrade
+    version in previous-version.txt before overwriting version.txt, so the
+    GUI banner can show "upgraded from X to Y". Missing file → "" (dev runs
+    or first install), never an error.
+    """
+    import emrg.server.daemon as daemon_mod
+    install = tmp_path / ".emrg" / "install"
+    install.mkdir(parents=True)
+    (install / "version.txt").write_text("0.2.61\n", encoding="utf-8")
+    (install / "previous-version.txt").write_text("0.2.57\n", encoding="utf-8")
+
+    monkeypatch.setattr(daemon_mod.Path, "home", lambda: tmp_path)
+
+    server = _make_server()
+    assert server._previous_installed_version() == "0.2.57"
+
+    # Missing file → "" (no crash)
+    empty = tmp_path / "no-install"
+    monkeypatch.setattr(daemon_mod.Path, "home", lambda: empty)
+    assert server._previous_installed_version() == ""
+
+    # Pong payload includes the field
+    monkeypatch.setattr(daemon_mod.Path, "home", lambda: tmp_path)
+    writer = _FakeWriter()
+    import asyncio
+    asyncio.run(server._process_message({"type": "ping"}, writer))
+    frame = _last_frame(writer)
+    assert frame["type"] == "pong"
+    assert frame["current_version"] == "0.2.61"
+    assert frame["previous_version"] == "0.2.57"