diff --git a/config/quality/eslint-suppressions.json b/config/quality/eslint-suppressions.json
index 8f68e5f07c..81775983bd 100644
--- a/config/quality/eslint-suppressions.json
+++ b/config/quality/eslint-suppressions.json
@@ -1018,11 +1018,6 @@
       "count": 1
     }
   },
-  "src/lib/api/modelTestRunner.ts": {
-    "no-restricted-imports": {
-      "count": 1
-    }
-  },
   "src/lib/api/proxyRegistryRouteHandlers.ts": {
     "no-restricted-imports": {
       "count": 1
diff --git a/docs/security/BAN_DETECTION.md b/docs/security/BAN_DETECTION.md
index 4f72fe7708..faf585267e 100644
--- a/docs/security/BAN_DETECTION.md
+++ b/docs/security/BAN_DETECTION.md
@@ -38,7 +38,7 @@ this service has been disabled in this account                  (Antigravity)
 > copy is `ACCOUNT_DEACTIVATED_SIGNALS` in `open-sse/services/accountFallback.ts`;
 > treat the block above as a snapshot.
 
-Two adjacent, **separate** signal tables live in the same file and are *not* part
+Two adjacent, **separate** signal tables live in the same file and are _not_ part
 of banned-keyword detection:
 
 - `CREDITS_EXHAUSTED_SIGNALS` — billing/quota depleted (`insufficient_quota`,
@@ -70,7 +70,7 @@ upstream error response
   narrower **`deactivated`** label (`isActive=false` when the connection has no
   spare API keys) is written by the inline `chatCore.ts` path on **HTTP 401 / 403**
   (classified via `classifyProviderError` → `ACCOUNT_DEACTIVATED`). Note the
-  `markAccountUnavailable()` path writes a *different* terminal status —
+  `markAccountUnavailable()` path writes a _different_ terminal status —
   **`expired`** — for the same `ACCOUNT_DEACTIVATED` signal (via
   `resolveTerminalConnectionStatus`), so the same ban can surface as either
   `deactivated` or `expired` depending on which path handled the response. (The
@@ -86,7 +86,7 @@ every failed upstream request flows through — it is **not** gated to
 OAuth/subscription scrapers. The resulting terminal state is per **connection**,
 not per provider.
 
-That said, the built-in *strings* are oriented toward subscription/OAuth
+That said, the built-in _strings_ are oriented toward subscription/OAuth
 providers with real ban risk (ChatGPT Web, Claude Web, Codex, Muse Spark,
 Antigravity). An API-key provider will only trip the detector if its error body
 literally contains one of the substrings.
@@ -136,14 +136,62 @@ There is no separate "clear ban flag" button — recovery is re-test, re-auth, o
 re-enable, matching the general terminal-state rule in
 [RESILIENCE_GUIDE](../architecture/RESILIENCE_GUIDE.md).
 
+## Probe isolation (model test-all)
+
+A **probe-origin failure** (model test-all / health-check dispatches executed
+inside `runAsProbe`) never removes a connection from the pool (#9817): it is
+**recorded for visibility** (`last_error`, `last_error_type`, `error_code`,
+`last_error_at`) but skips **every** routing mutation — cooldowns, terminal
+status (`banned` / `deactivated` / `credits_exhausted`), per-model lockouts,
+the provider circuit breaker, the 5-minute quota cache, OAuth token refresh
+and auto-disable. Only a real request-path failure deactivates. The recorded
+error is what makes a flagged account visible in the dashboard while it stays
+serving traffic.
+
+The single decision point is `shouldIsolateProbeFailures()`
+(`src/shared/utils/probeOrigin.ts`), consulted by **every** site that could
+mutate routing state from a probe-origin failure:
+
+- `markAccountUnavailable` (`auth.ts`) — record-only (`lastError` raw text,
+  `lastErrorType`, `errorCode`, `lastErrorAt`; deliberately **no**
+  `backoffLevel`, which would trigger the selection-time auto-decay and wipe
+  the record)
+- `maybeAutoDisableBannedAccount` — no auto-disable
+- `chatCore` — FORBIDDEN, ACCOUNT_DEACTIVATED, QUOTA_EXHAUSTED (record-only,
+  no terminal `credits_exhausted`), GEO_BLOCKED (no 24h exclusion),
+  MODEL_NOT_FOUND (no `lockModel`), the codex 429 account-rotation failover
+  (no `markCodexScopeRateLimited`, no persisted `rate_limited_until`, no
+  session-affinity clear), `persistCodexQuotaState` (no quota-state write,
+  no cache invalidation), `recordKeyHealthStatus` (key-health rotator
+  untouched)
+- OAuth refresh — both the proactive refresh in the executor base
+  (`base.ts` `execute()`, no refresh-token rotation consumed) and the
+  reactive 401/403 path in `chatCore` (no `expired` deactivation)
+- `chat.ts` — provider circuit breaker and the 5-minute quota cache
+  (`markAccountExhaustedFrom429`) never degraded
+
+The recorded error is what makes a flagged account visible in the dashboard
+while it stays serving traffic. Note: the probe record stores the **raw**
+(unsliced) error text, unlike the real path's `slice(0,100)` truncation.
+
+Operators who use test-all as a maintenance tool can restore the historical
+behavior (probe counts as a real generation) via either:
+
+- the `probeCanDisable` setting (`POST /api/settings` with
+  `{"probeCanDisable": true}`, or a direct `key_value` DB edit), or
+- feature flag **`PROBE_CAN_DISABLE=true`** (env or DB override; wins over the
+  setting).
+
+Fail-safe: if the flag or settings lookup throws, isolation stays ON.
+
 ## Source files
 
-| Concern | File |
-| --- | --- |
-| Signal tables + match | `open-sse/services/accountFallback.ts` |
-| Terminalization / persistence | `src/sse/services/auth.ts` (`markAccountUnavailable`, `resolveTerminalConnectionStatus`, `clearAccountError`) |
-| Auto-disable scope | `src/shared/utils/autoDisableBanned.ts`, `src/sse/services/autoDisableBannedAccount.ts` |
-| Inline classification | `open-sse/handlers/chatCore.ts`, `open-sse/services/errorClassifier.ts` |
-| Terminal-state recovery exclusion | `src/lib/quota/connectionRecovery.ts` |
-| Custom-keyword runtime load | `src/lib/config/runtimeSettings.ts` (`setCustomBannedSignals`) |
-| Settings UI | `src/app/(dashboard)/dashboard/settings/components/SecurityTab.tsx` |
+| Concern                           | File                                                                                                          |
+| --------------------------------- | ------------------------------------------------------------------------------------------------------------- |
+| Signal tables + match             | `open-sse/services/accountFallback.ts`                                                                        |
+| Terminalization / persistence     | `src/sse/services/auth.ts` (`markAccountUnavailable`, `resolveTerminalConnectionStatus`, `clearAccountError`) |
+| Auto-disable scope                | `src/shared/utils/autoDisableBanned.ts`, `src/sse/services/autoDisableBannedAccount.ts`                       |
+| Inline classification             | `open-sse/handlers/chatCore.ts`, `open-sse/services/errorClassifier.ts`                                       |
+| Terminal-state recovery exclusion | `src/lib/quota/connectionRecovery.ts`                                                                         |
+| Custom-keyword runtime load       | `src/lib/config/runtimeSettings.ts` (`setCustomBannedSignals`)                                                |
+| Settings UI                       | `src/app/(dashboard)/dashboard/settings/components/SecurityTab.tsx`                                           |
diff --git a/open-sse/executors/base.ts b/open-sse/executors/base.ts
index c91cb5cbb7..877431b68e 100644
--- a/open-sse/executors/base.ts
+++ b/open-sse/executors/base.ts
@@ -103,6 +103,7 @@ import {
 } from "./base/headers.ts";
 import { applyPeerTraceHeader } from "@/shared/resilience/peerRouting";
 import { applyClineProtocolHeaders } from "@/shared/utils/clineAuth";
+import { isProbeContext } from "@/shared/utils/probeOrigin";
 // Header helpers extracted to a pure leaf; re-exported for external importers
 // (executors + tests) that import them from "./base.ts".
 export {
@@ -689,7 +690,10 @@ export class BaseExecutor {
     // Track per-URL intra-retry attempts to avoid infinite loops
     const retryAttemptsByUrl: Record<number, number> = {};
 
-    if (this.needsRefresh(credentials)) {
+    // Probe-origin dispatches must not consume a refresh-token rotation —
+    // routing state untouched; the reactive 401/403 path is probe-guarded
+    // in chatCore (#9817).
+    if (!isProbeContext() && this.needsRefresh(credentials)) {
       try {
         // Fix A: wire onCredentialsRefreshed through runWithOnPersist so it runs
         // INSIDE the per-connection mutex inside getAccessToken. Not every
@@ -800,7 +804,14 @@ export class BaseExecutor {
         activeCredentials
       );
       const url = this.buildUrl(model, stream, urlIndex, requestCredentials);
-      const headers = this.buildHeaders(requestCredentials, stream, clientHeaders, model, undefined, body);
+      const headers = this.buildHeaders(
+        requestCredentials,
+        stream,
+        clientHeaders,
+        model,
+        undefined,
+        body
+      );
       applyConfiguredUserAgent(headers, requestCredentials?.providerSpecificData);
 
       // Strip OpenAI SDK (X-Stainless-*) metadata + normalize SDK-derived User-Agent
diff --git a/open-sse/executors/gitlab.ts b/open-sse/executors/gitlab.ts
index fa0b22c5c1..b82d5c47aa 100644
--- a/open-sse/executors/gitlab.ts
+++ b/open-sse/executors/gitlab.ts
@@ -10,6 +10,7 @@ import {
 } from "./base.ts";
 import { FETCH_TIMEOUT_MS } from "../config/constants.ts";
 import { getAccessToken } from "../services/tokenRefresh.ts";
+import { isProbeContext } from "@/shared/utils/probeOrigin";
 import { prepareToolMessages, buildToolAwareResult } from "../translator/webTools.ts";
 import {
   buildStreamingResponse,
@@ -208,9 +209,7 @@ function buildToolExchangePrompt(messages: OpenAIMessage[]): string {
     const line = renderConversationTurn(message, role, text);
     if (line) convo.push(line);
   }
-  const header = systemParts.length
-    ? `System instructions:\n${systemParts.join("\n\n")}\n\n`
-    : "";
+  const header = systemParts.length ? `System instructions:\n${systemParts.join("\n\n")}\n\n` : "";
   const body = `${header}${convo.join(
     "\n\n"
   )}\n\nContinue the response using the tool result above; do not repeat the tool call.`.trim();
@@ -672,7 +671,9 @@ export class GitlabExecutor extends BaseExecutor {
     }
 
     let activeCredentials = input.credentials;
-    if (this.needsRefresh(activeCredentials)) {
+    // Probe-origin dispatches must not consume a refresh-token rotation —
+    // routing state untouched; mirrors the base.ts guard (#9817).
+    if (!isProbeContext() && this.needsRefresh(activeCredentials)) {
       const refreshed = await this.refreshCredentials(activeCredentials, input.log || null);
       if (refreshed) {
         activeCredentials = mergeCredentials(activeCredentials, refreshed);
diff --git a/open-sse/handlers/chatCore.ts b/open-sse/handlers/chatCore.ts
index d93d3d1482..3555467a40 100644
--- a/open-sse/handlers/chatCore.ts
+++ b/open-sse/handlers/chatCore.ts
@@ -397,6 +397,7 @@ import {
 } from "../utils/aiSdkCompat.ts";
 import { generateRequestId } from "@/shared/utils/requestId";
 import { isLocalStreamLifecycleError } from "@/shared/utils/circuitBreaker";
+import { shouldIsolateProbeFailures } from "@/shared/utils/probeOrigin";
 import { extractFacts } from "@/lib/memory/extraction";
 import { handleToolCallExecution } from "@/lib/skills/interception";
 import { OMNIROUTE_RESPONSE_HEADERS } from "@/shared/constants/headers";
@@ -3022,7 +3023,11 @@ export async function handleChatCore({
               const res = normalizeExecutorResult(rawExecutorResult);
               trace("post_executor", { status: res?.response?.status });
 
-              if (provider === "codex" && attemptConnectionId) {
+              if (
+                provider === "codex" &&
+                attemptConnectionId &&
+                !(await shouldIsolateProbeFailures())
+              ) {
                 try {
                   const persistedQuota = await persistCodexChildQuotaResponse({
                     connectionId: String(attemptConnectionId),
@@ -3054,7 +3059,11 @@ export async function handleChatCore({
                 stage: "provider_response_started",
               });
 
-              if (res.response.status === 401 && executionConnectionId) {
+              if (
+                res.response.status === 401 &&
+                executionConnectionId &&
+                !(await shouldIsolateProbeFailures())
+              ) {
                 recordKeyHealthStatus(401, execCreds);
               }
 
@@ -3084,7 +3093,10 @@ export async function handleChatCore({
                 !managedLease &&
                 comboStrategy !== "context-relay" &&
                 res.response.status === 429 &&
-                attempts < maxAttempts - 1
+                attempts < maxAttempts - 1 &&
+                // Probe-origin (test-all) 429 must not rotate accounts or persist
+                // cooldowns — routing state untouched (#9817).
+                !(await shouldIsolateProbeFailures())
               ) {
                 const failedConnectionId =
                   executionConnectionId || credentials?.connectionId || connectionId;
@@ -3689,10 +3701,15 @@ export async function handleChatCore({
   }
 
   // Handle 401/403 - try token refresh using executor
+  // T-PROBE: probe-origin failures never attempt the refresh — a probe must
+  // not consume a rotating refresh token nor persist an "expired"
+  // deactivation on refresh failure (#9817). The 401/403 then flows into
+  // the normal providerFailure classification (record-only in probe mode).
   if (
     (providerResponse.status === HTTP_STATUS.UNAUTHORIZED ||
       providerResponse.status === HTTP_STATUS.FORBIDDEN) &&
-    !hadStreamOptions // Skip refresh if failure may be from stream_options removal, not auth
+    !hadStreamOptions && // Skip refresh if failure may be from stream_options removal, not auth
+    !(await shouldIsolateProbeFailures())
   ) {
     // Fix A: wrap refreshCredentials in runWithOnPersist so the persist callback
     // executes INSIDE the per-connection mutex held by getAccessToken. This makes
@@ -3972,17 +3989,34 @@ export async function handleChatCore({
     if (errorConnectionId && errorType) {
       try {
         if (errorType === PROVIDER_ERROR_TYPES.FORBIDDEN) {
-          await updateProviderConnection(errorConnectionId, {
-            isActive: false,
-            testStatus: "banned",
-            lastErrorType: errorType,
-            lastError: message,
-            errorCode: statusCode,
-          });
-          console.warn(
-            `[provider] Node ${errorConnectionId} banned (${statusCode}) — disabling permanently`
-          );
+          // T-PROBE: a probe-origin failure (model test-all) must never
+          // remove the connection from the pool — record but stay active.
+          if (await shouldIsolateProbeFailures()) {
+            await updateProviderConnection(errorConnectionId, {
+              lastErrorType: errorType,
+              lastError: message,
+              errorCode: statusCode,
+              lastErrorAt: new Date().toISOString(),
+            });
+            console.warn(
+              `[provider] Node ${errorConnectionId} probe ${errorType} (${statusCode}) — connection stays active`
+            );
+          } else {
+            await updateProviderConnection(errorConnectionId, {
+              isActive: false,
+              testStatus: "banned",
+              lastErrorType: errorType,
+              lastError: message,
+              errorCode: statusCode,
+            });
+            console.warn(
+              `[provider] Node ${errorConnectionId} banned (${statusCode}) — disabling permanently`
+            );
+          }
         } else if (errorType === PROVIDER_ERROR_TYPES.ACCOUNT_DEACTIVATED) {
+          // T-PROBE: probe-origin failures (test-all) never deactivate —
+          // record but stay active; Plan A (extra keys) stays first so the
+          // real path keeps its existing priority (#9817).
           // Plan A: if connection has extra API keys, don't disable — only the failing key is affected.
           // Single-key connections still get disabled as before.
           if (
@@ -4000,6 +4034,16 @@ export async function handleChatCore({
             console.warn(
               `[provider] Node ${errorConnectionId} account deactivated (${statusCode}) — has extra keys, keeping connection active`
             );
+          } else if (await shouldIsolateProbeFailures()) {
+            await updateProviderConnection(errorConnectionId, {
+              lastErrorType: errorType,
+              lastError: message,
+              errorCode: statusCode,
+              lastErrorAt: new Date().toISOString(),
+            });
+            console.warn(
+              `[provider] Node ${errorConnectionId} probe ${errorType} (${statusCode}) — connection stays active`
+            );
           } else {
             await updateProviderConnection(errorConnectionId, {
               isActive: false,
@@ -4013,73 +4057,90 @@ export async function handleChatCore({
             );
           }
         } else if (errorType === PROVIDER_ERROR_TYPES.QUOTA_EXHAUSTED) {
-          // Kimi's 403 says "billing cycle" for both an exhausted subscription and a
-          // temporary request window. Read its official usage endpoint before making
-          // the connection terminal: a non-zero Weekly quota plus an empty Ratelimit
-          // window must recover automatically at the reported reset time.
-          let kimiRateLimitResetAt: string | null = null;
-          if (provider === "kimi-coding") {
-            try {
-              const { fetchAndPersistProviderLimits } = await import("@/lib/usage/providerLimits");
-              const { usage } = await fetchAndPersistProviderLimits(errorConnectionId, "manual");
-              kimiRateLimitResetAt = getKimiTemporaryRateLimitResetAt(usage);
-            } catch {
-              // Preserve the existing quota handling when Kimi's usage endpoint is unavailable.
-            }
-          }
-
-          // Providers with per-model quotas — lock the model only, not the connection
-          const quotaCooldownMs = kimiRateLimitResetAt
-            ? Math.max(new Date(kimiRateLimitResetAt).getTime() - Date.now(), 0)
-            : retryAfterMs || COOLDOWN_MS.rateLimit;
-          const accountSemaphoreKey = resolveAccountSemaphoreKey({
-            provider,
-            model: currentModel,
-            connectionId: errorConnectionId,
-            credentials,
-          });
-          if (accountSemaphoreKey) {
-            markAccountSemaphoreBlocked(accountSemaphoreKey, quotaCooldownMs);
-          }
-          if (kimiRateLimitResetAt) {
+          // T-PROBE: probe-origin failures never write quota state —
+          // `testStatus: "credits_exhausted"` is terminal and removes the
+          // connection from the pool; semaphore locks and per-model quota
+          // lockouts are routing mutations too. Record only (#9817).
+          if (await shouldIsolateProbeFailures()) {
             await updateProviderConnection(errorConnectionId, {
-              testStatus: "unavailable",
-              rateLimitedUntil: kimiRateLimitResetAt,
-              backoffLevel: 0,
-              lastErrorType: PROVIDER_ERROR_TYPES.RATE_LIMITED,
-              lastError: message,
-              errorCode: statusCode,
-            });
-            console.warn(
-              `[provider] Node ${errorConnectionId} Kimi request window exhausted (${statusCode}) — retrying after ${kimiRateLimitResetAt}`
-            );
-          } else if (isModelScope() && errorConnectionId) {
-            const lockFn = provider === "antigravity" ? lockExactModel : lockModel;
-            lockFn(provider, errorConnectionId, model, "quota_exhausted", quotaCooldownMs);
-            console.warn(
-              `[provider] Node ${errorConnectionId} ModelScope model quota exhausted (${statusCode}) for ${model} - ${Math.ceil(quotaCooldownMs / 1000)}s (connection stays active)`
-            );
-          } else if (
-            lockModelIfPerModelQuota(
-              provider,
-              errorConnectionId,
-              model,
-              "quota_exhausted",
-              quotaCooldownMs
-            )
-          ) {
-            const quotaScope = getQuotaScopeLabelForProvider(provider, model);
-            console.warn(
-              `[provider] Node ${errorConnectionId} ${quotaScope}-only quota exhausted (${statusCode}) for ${model} - ${Math.ceil(quotaCooldownMs / 1000)}s (cooldown_scope=${quotaScope}, ttl_source=${retryAfterMs ? "upstream" : "inferred"}, connection stays active)`
-            );
-          } else {
-            await updateProviderConnection(errorConnectionId, {
-              testStatus: "credits_exhausted",
               lastErrorType: errorType,
               lastError: message,
               errorCode: statusCode,
+              lastErrorAt: new Date().toISOString(),
             });
-            console.warn(`[provider] Node ${errorConnectionId} exhausted quota (${statusCode})`);
+            console.warn(
+              `[provider] Node ${errorConnectionId} probe ${errorType} (${statusCode}) — connection stays active`
+            );
+          } else {
+            // Kimi's 403 says "billing cycle" for both an exhausted subscription and a
+            // temporary request window. Read its official usage endpoint before making
+            // the connection terminal: a non-zero Weekly quota plus an empty Ratelimit
+            // window must recover automatically at the reported reset time.
+            let kimiRateLimitResetAt: string | null = null;
+            if (provider === "kimi-coding") {
+              try {
+                const { fetchAndPersistProviderLimits } =
+                  await import("@/lib/usage/providerLimits");
+                const { usage } = await fetchAndPersistProviderLimits(errorConnectionId, "manual");
+                kimiRateLimitResetAt = getKimiTemporaryRateLimitResetAt(usage);
+              } catch {
+                // Preserve the existing quota handling when Kimi's usage endpoint is unavailable.
+              }
+            }
+
+            // Providers with per-model quotas — lock the model only, not the connection
+            const quotaCooldownMs = kimiRateLimitResetAt
+              ? Math.max(new Date(kimiRateLimitResetAt).getTime() - Date.now(), 0)
+              : retryAfterMs || COOLDOWN_MS.rateLimit;
+            const accountSemaphoreKey = resolveAccountSemaphoreKey({
+              provider,
+              model: currentModel,
+              connectionId: errorConnectionId,
+              credentials,
+            });
+            if (accountSemaphoreKey) {
+              markAccountSemaphoreBlocked(accountSemaphoreKey, quotaCooldownMs);
+            }
+            if (kimiRateLimitResetAt) {
+              await updateProviderConnection(errorConnectionId, {
+                testStatus: "unavailable",
+                rateLimitedUntil: kimiRateLimitResetAt,
+                backoffLevel: 0,
+                lastErrorType: PROVIDER_ERROR_TYPES.RATE_LIMITED,
+                lastError: message,
+                errorCode: statusCode,
+              });
+              console.warn(
+                `[provider] Node ${errorConnectionId} Kimi request window exhausted (${statusCode}) — retrying after ${kimiRateLimitResetAt}`
+              );
+            } else if (isModelScope() && errorConnectionId) {
+              const lockFn = provider === "antigravity" ? lockExactModel : lockModel;
+              lockFn(provider, errorConnectionId, model, "quota_exhausted", quotaCooldownMs);
+              console.warn(
+                `[provider] Node ${errorConnectionId} ModelScope model quota exhausted (${statusCode}) for ${model} - ${Math.ceil(quotaCooldownMs / 1000)}s (connection stays active)`
+              );
+            } else if (
+              lockModelIfPerModelQuota(
+                provider,
+                errorConnectionId,
+                model,
+                "quota_exhausted",
+                quotaCooldownMs
+              )
+            ) {
+              const quotaScope = getQuotaScopeLabelForProvider(provider, model);
+              console.warn(
+                `[provider] Node ${errorConnectionId} ${quotaScope}-only quota exhausted (${statusCode}) for ${model} - ${Math.ceil(quotaCooldownMs / 1000)}s (cooldown_scope=${quotaScope}, ttl_source=${retryAfterMs ? "upstream" : "inferred"}, connection stays active)`
+              );
+            } else {
+              await updateProviderConnection(errorConnectionId, {
+                testStatus: "credits_exhausted",
+                lastErrorType: errorType,
+                lastError: message,
+                errorCode: statusCode,
+              });
+              console.warn(`[provider] Node ${errorConnectionId} exhausted quota (${statusCode})`);
+            }
           }
         } else if (errorType === PROVIDER_ERROR_TYPES.UNAUTHORIZED) {
           // Normal 401 (token/session auth issue): keep account active for refresh/re-auth.
@@ -4121,11 +4182,15 @@ export async function handleChatCore({
             lastError: message,
             errorCode: statusCode,
           });
-          try {
-            const { setConnectionRateLimitUntil } = await import("@/lib/db/providers");
-            setConnectionRateLimitUntil(errorConnectionId, Date.now() + geoCooldownMs);
-          } catch {
-            // DB write failure must never break the fallback loop
+          // T-PROBE: the 24h exclusion is a routing mutation — a probe must
+          // not push a connection into a day-long cooldown (#9817).
+          if (!(await shouldIsolateProbeFailures())) {
+            try {
+              const { setConnectionRateLimitUntil } = await import("@/lib/db/providers");
+              setConnectionRateLimitUntil(errorConnectionId, Date.now() + geoCooldownMs);
+            } catch {
+              // DB write failure must never break the fallback loop
+            }
           }
           console.warn(
             `[provider] Node ${errorConnectionId} geo-blocked (${statusCode}) — excluded for ${Math.ceil(geoCooldownMs / 1000)}s, trying other accounts`
@@ -4136,16 +4201,20 @@ export async function handleChatCore({
           // otherwise degenerate into a 429 rate-limit storm). Connection stays
           // active since only the specific model is unavailable. (#6827)
           const notFoundCooldownMs = COOLDOWN_MS.notFound;
-          lockModel(
-            provider,
-            errorConnectionId,
-            currentModel,
-            "model_not_found",
-            notFoundCooldownMs
-          );
-          console.warn(
-            `[provider] Node ${errorConnectionId} model not found (${statusCode}) for ${currentModel} - locking model for ${Math.ceil(notFoundCooldownMs / 1000)}s (connection stays active)`
-          );
+          // T-PROBE: the model lockout is a routing mutation — a probe must
+          // not lock a model for the cooldown window (#9817).
+          if (!(await shouldIsolateProbeFailures())) {
+            lockModel(
+              provider,
+              errorConnectionId,
+              currentModel,
+              "model_not_found",
+              notFoundCooldownMs
+            );
+            console.warn(
+              `[provider] Node ${errorConnectionId} model not found (${statusCode}) for ${currentModel} - locking model for ${Math.ceil(notFoundCooldownMs / 1000)}s (connection stays active)`
+            );
+          }
         }
       } catch {
         // Best-effort state update; request flow should continue with fallback handling.
diff --git a/src/lib/api/modelTestRunner.ts b/src/lib/api/modelTestRunner.ts
index f68454f6f5..c72248f55a 100644
--- a/src/lib/api/modelTestRunner.ts
+++ b/src/lib/api/modelTestRunner.ts
@@ -8,7 +8,7 @@ import {
   extractComboTestResponseText,
   extractComboTestStreamResult,
 } from "@/lib/combos/testHealth";
-import { getCustomModels } from "@/lib/localDb";
+import { getCustomModels } from "@/lib/db/models";
 import { getProviderNodeById } from "@/lib/db/providers";
 import { sanitizeErrorMessage } from "@omniroute/open-sse/utils/error";
 import { withRateLimit } from "@omniroute/open-sse/services/rateLimitManager";
@@ -18,6 +18,7 @@ import {
 } from "@omniroute/open-sse/services/accountFallback";
 import { looksLikeQuotaExhausted } from "@/shared/utils/classify429";
 import { getTrustedLocalRateLimitError } from "@omniroute/open-sse/services/rateLimitManager/errors";
+import { runAsProbe } from "@/shared/utils/probeOrigin";
 import { isConnectionUnavailableToAuxiliaryActivity } from "@/lib/exclusiveLeaseIsolation";
 
 const INTERNAL_ORIGIN = "http://omniroute.internal";
@@ -482,11 +483,14 @@ export async function runSingleModelTest(
         providerId,
         connectionId,
         fullModelStr,
-        (signal) => runInner(signal),
+        // T-PROBE: wrap the scheduled fn, not the withRateLimit call — a
+        // queued Bottleneck job executes from its own async resource and
+        // would otherwise run outside the probe context below.
+        (signal) => runAsProbe(() => runInner(signal)),
         controller.signal
       );
     } else {
-      res = await runInner(controller.signal);
+      res = await runAsProbe(() => runInner(controller.signal));
     }
   } catch (error: unknown) {
     clearTimeout(timeoutHandle);
@@ -566,9 +570,14 @@ export async function runSingleModelTest(
     let responseText = "";
     let streamError: ModelTestResponseText["error"];
     try {
-      const parsedResponse = await extractModelTestResponseText(
-        res,
-        !isEmbedding && !isRerank && streamChat
+      // T-PROBE: consume the stream inside the probe context too — the SSE
+      // body is transformed by chatCore/chatHelpers generator code that
+      // resumes in the CONSUMER's async context. Without this wrapper, an
+      // error frame inside a 200 stream (Sentinel blocks, "account
+      // deactivated") would run outside runAsProbe and could still reach
+      // markAccountUnavailable (#9817).
+      const parsedResponse = await runAsProbe(() =>
+        extractModelTestResponseText(res, !isEmbedding && !isRerank && streamChat)
       );
       responseText = parsedResponse.text;
       streamError = parsedResponse.error;
diff --git a/src/shared/utils/probeOrigin.ts b/src/shared/utils/probeOrigin.ts
new file mode 100644
index 0000000000..1c426e117c
--- /dev/null
+++ b/src/shared/utils/probeOrigin.ts
@@ -0,0 +1,63 @@
+/**
+ * Probe-origin tracking via AsyncLocalStorage.
+ *
+ * Convention: ANY probe flow (model test-all, future batch tests,
+ * credential-health if it ever routes through the chat path) MUST execute
+ * inside runAsProbe() so deactivation guards can refuse probe-origin
+ * failures (invariant #9817: only a real request-path failure deactivates
+ * a connection). Pinned by tests/unit/probe-testall-isolation.test.ts.
+ *
+ * NOTE: when a probe dispatches through a scheduler with a queue
+ * (Bottleneck via withRateLimit), runAsProbe must wrap the scheduled fn
+ * itself — a queued job otherwise executes outside this context
+ * (pinned by the queued-scheduler test below).
+ *
+ * EXCEPTIONS (deliberate, documented in the PR): tokenHealthCheck refresh
+ * failures keep deactivating (re-auth semantics — a dead refresh token is
+ * a real death, not a probe artifact), and circuit-breaker HALF_OPEN
+ * probes are real generations by design. Those flows stay outside
+ * runAsProbe.
+ */
+import { AsyncLocalStorage } from "node:async_hooks";
+
+const probeContext = new AsyncLocalStorage<{ probe: true }>();
+
+export function runAsProbe<T>(fn: () => Promise<T>): Promise<T> {
+  return probeContext.run({ probe: true }, fn);
+}
+
+export function isProbeContext(): boolean {
+  return probeContext.getStore() !== undefined;
+}
+
+/**
+ * Central probe-isolation decision used by every deactivation site.
+ *
+ * True when the current execution is probe-origin AND the opt-in setting
+ * `probeCanDisable` is OFF (default): the probe failure is recorded but
+ * must never remove the connection from the pool (cooldowns, terminal
+ * status, per-model lockouts, auto-disable, circuit breaker). Operators
+ * who use test-all as a maintenance tool set `probeCanDisable: true` to
+ * restore the historical behavior where a probe counts as a real
+ * generation.
+ */
+export async function shouldIsolateProbeFailures(): Promise<boolean> {
+  if (!isProbeContext()) return false;
+  // Feature-flag kill-switch (env/DB override; fail-safe false like the
+  // AUTH_LOG_INCLUDE_ACCOUNT_ID usage): PROBE_CAN_DISABLE restores the
+  // historical behavior where a probe counts as a real generation.
+  try {
+    const { isFeatureFlagEnabled } = await import("@/shared/utils/featureFlags");
+    if (isFeatureFlagEnabled("PROBE_CAN_DISABLE")) return false;
+  } catch {
+    // Fail-safe: on lookup failure the isolation stays ON.
+  }
+  try {
+    const { getCachedSettings } = await import("@/lib/db/readCache");
+    const settings = await getCachedSettings();
+    return !settings.probeCanDisable;
+  } catch {
+    // Fail-safe: on settings-lookup failure the isolation stays ON.
+    return true;
+  }
+}
diff --git a/src/shared/validation/settingsSchemas.ts b/src/shared/validation/settingsSchemas.ts
index c4cb849573..83d87893f9 100644
--- a/src/shared/validation/settingsSchemas.ts
+++ b/src/shared/validation/settingsSchemas.ts
@@ -174,6 +174,10 @@ export const updateSettingsSchema = z.object({
     )
     .optional(),
   customBannedSignals: z.array(z.string().max(200)).optional(),
+  // #9817: opt-in (default off) — lets a probe-origin (model test-all)
+  // failure deactivate a connection like real traffic. Off by default:
+  // probe failures are recorded but never mutate routing state.
+  probeCanDisable: z.boolean().optional(),
   debugMode: z.boolean().optional(),
   logToolSources: z.boolean().optional(),
   hiddenSidebarItems: z.array(z.enum(HIDEABLE_SIDEBAR_ITEM_IDS)).optional(),
diff --git a/src/sse/handlers/chat.ts b/src/sse/handlers/chat.ts
index 4e5ab7b6ef..b200674d32 100644
--- a/src/sse/handlers/chat.ts
+++ b/src/sse/handlers/chat.ts
@@ -126,6 +126,7 @@ import { classify429FromError, type FailureKind } from "@/shared/utils/classify4
 import { isSubscriptionQuotaText } from "@omniroute/open-sse/services/quotaTextCooldowns.ts";
 import { resolveUseUpstream429BreakerHints } from "@/shared/utils/providerHints";
 import { isFeatureFlagEnabled } from "@/shared/utils/featureFlags";
+import { shouldIsolateProbeFailures } from "@/shared/utils/probeOrigin";
 import { getCircuitBreaker, isLocalStreamLifecycleError } from "../../shared/utils/circuitBreaker";
 import { markAccountExhaustedFrom429 } from "../../domain/quotaCache";
 import { resolveForcedConnectionForCredentialPool } from "../services/sessionAffinityPin.ts";
@@ -1664,7 +1665,10 @@ async function handleSingleModelChat(
           credentials?.allRateLimited &&
           isProviderBreakerFailureStatus(breakerFailureStatus) &&
           !isNetworkError &&
-          !isQueueTimeout
+          !isQueueTimeout &&
+          // Probe-origin dispatches must not degrade the provider breaker —
+          // routing state untouched (#9817).
+          !(await shouldIsolateProbeFailures())
         ) {
           breaker._onFailure();
         }
@@ -2206,7 +2210,10 @@ async function handleSingleModelChat(
         const passthroughModels = credentials.providerSpecificData?.passthroughModels;
         if (
           result.status === 429 &&
-          shouldMarkAccountExhaustedFrom429(provider, model, passthroughModels, failureKind)
+          shouldMarkAccountExhaustedFrom429(provider, model, passthroughModels, failureKind) &&
+          // T-PROBE: a probe must not poison the 5min quotaCache for real
+          // traffic (#9817).
+          !(await shouldIsolateProbeFailures())
         ) {
           markAccountExhaustedFrom429(credentials.connectionId, provider);
         }
@@ -2308,7 +2315,12 @@ async function handleSingleModelChat(
         continue;
       }
 
-      if (shouldTripProviderBreakerForResult(result, isCombo, forceLiveComboTest)) {
+      // T-PROBE: a probe failure must not degrade the provider-wide circuit
+      // breaker for real traffic (#9817).
+      if (
+        !(await shouldIsolateProbeFailures()) &&
+        shouldTripProviderBreakerForResult(result, isCombo, forceLiveComboTest)
+      ) {
         breaker._onFailure();
       }
 
diff --git a/src/sse/services/auth.ts b/src/sse/services/auth.ts
index 96a0de2761..7f831b81c5 100644
--- a/src/sse/services/auth.ts
+++ b/src/sse/services/auth.ts
@@ -126,6 +126,7 @@ import {
   getNextFromDeckSync,
   planNextFromDeckSync,
 } from "@/shared/utils/shuffleDeck";
+import { shouldIsolateProbeFailures } from "@/shared/utils/probeOrigin";
 import {
   applyExclusiveConnectionLeasePolicy,
   invalidateManagedConnectionLease,
@@ -2446,6 +2447,33 @@ export async function markAccountUnavailable(
       effectiveProviderProfile
     );
 
+    // T-PROBE: probe-origin failures (model test-all) must never remove the
+    // connection from the pool. Record the failure for visibility but leave
+    // ALL routing state untouched — cooldowns, terminal status, per-model
+    // lockouts (T09 codex-scope, per-model quota, agentrouter #10334) and
+    // auto-disable. Only a real request-path failure deactivates (#9817);
+    // the opt-in setting probeCanDisable restores the historical behavior.
+    if (await shouldIsolateProbeFailures()) {
+      await updateProviderConnection(connectionId, {
+        // lastError kept RAW (full text) — maximal probe visibility; the
+        // divergence vs the normal path's slice(0,100) is intentional.
+        // backoffLevel is deliberately NOT written: a positive backoff
+        // triggers the selection-time auto-decay (resetConnectionBackoff,
+        // auth.ts getProviderCredentials) which wipes lastError back to
+        // NULL on the next attempt — silently destroying the probe record.
+        // The backoff is also routing state a probe must not touch (#9817).
+        lastError: errorText,
+        lastErrorType: fallbackResult.reason || null,
+        errorCode: status,
+        lastErrorAt: new Date().toISOString(),
+      });
+      log.warn(
+        "AUTH",
+        `[T-PROBE] ${connectionId.slice(0, 8)} ${provider ?? ""} failure ${status} recorded — connection stays in the pool`
+      );
+      return { shouldFallback: true, cooldownMs: 0 };
+    }
+
     // Read passthroughModels from connection config (user-configured per-model quota)
     const connProviderSpecificData = (conn?.providerSpecificData as Record<string, unknown>) || {};
     if (provider && conn) {
diff --git a/src/sse/services/autoDisableBannedAccount.ts b/src/sse/services/autoDisableBannedAccount.ts
index 2d1d8d33d1..b55a8b8417 100644
--- a/src/sse/services/autoDisableBannedAccount.ts
+++ b/src/sse/services/autoDisableBannedAccount.ts
@@ -9,6 +9,7 @@ import { getCachedSettings } from "@/lib/db/readCache";
 import { updateProviderConnection } from "@/lib/db/providers";
 import { resolveProviderId, WEB_COOKIE_PROVIDERS } from "@/shared/constants/providers";
 import { shouldAutoDisableBannedConnection } from "@/shared/utils/autoDisableBanned";
+import { shouldIsolateProbeFailures } from "@/shared/utils/probeOrigin";
 import * as log from "../utils/logger";
 
 /** Deactivate a connection after a permanent ban when settings and scope allow it. */
@@ -20,6 +21,15 @@ export async function maybeAutoDisableBannedAccount(input: {
   permanent?: boolean;
 }): Promise<void> {
   if (!input.permanent) return;
+  // T-PROBE: a probe-origin failure (model test-all) must never disable a
+  // connection — only a real request-path failure deactivates (#9817).
+  if (await shouldIsolateProbeFailures()) {
+    log.info(
+      "AUTH",
+      `Skipped auto-disable for ${input.connectionId.slice(0, 8)} — probe origin (permanent failure, connection stays active)`
+    );
+    return;
+  }
   try {
     const settings = await getCachedSettings();
     const scope = settings.autoDisableBannedScope;
diff --git a/tests/unit/probe-autodisable-isolation.test.ts b/tests/unit/probe-autodisable-isolation.test.ts
new file mode 100644
index 0000000000..5cb4479b67
--- /dev/null
+++ b/tests/unit/probe-autodisable-isolation.test.ts
@@ -0,0 +1,60 @@
+import { test } from "node:test";
+import assert from "node:assert/strict";
+import fs from "node:fs";
+import os from "node:os";
+import path from "node:path";
+
+const TEST_DATA_DIR = fs.mkdtempSync(path.join(os.tmpdir(), "omniroute-probe-autodisable-"));
+process.env.DATA_DIR = TEST_DATA_DIR;
+
+const core = await import("../../src/lib/db/core.ts");
+const settingsDb = await import("../../src/lib/db/settings.ts");
+const { createProviderConnection } = await import("../../src/lib/db/providers.ts");
+const { maybeAutoDisableBannedAccount } =
+  await import("../../src/sse/services/autoDisableBannedAccount.ts");
+const { runAsProbe } = await import("../../src/shared/utils/probeOrigin.ts");
+
+test.after(() => {
+  core.resetDbInstance();
+  fs.rmSync(TEST_DATA_DIR, { recursive: true, force: true });
+});
+
+function readIsActive(connId: string): unknown {
+  const db = core.getDbInstance() as unknown as {
+    prepare: (sql: string) => { get: (id: string) => { is_active: unknown } | undefined };
+  };
+  return db.prepare("SELECT is_active FROM provider_connections WHERE id = ?").get(connId)
+    ?.is_active;
+}
+
+async function setupConnection(): Promise<string> {
+  await settingsDb.updateSettings({ autoDisableBannedAccounts: true });
+  const conn = await createProviderConnection({
+    provider: "openai",
+    authType: "apikey",
+    name: "probe-autodisable",
+    apiKey: "sk-probe-autodisable", // pragma: allowlist secret
+    isActive: true,
+    testStatus: "active",
+  });
+  return String((conn as { id: string }).id);
+}
+
+const PROBE_INPUT = {
+  provider: "openai",
+  authType: "apikey",
+  connectionProvider: "openai",
+  permanent: true,
+};
+
+test("probe-origin permanent failure never disables the connection", async () => {
+  const connId = await setupConnection();
+  await runAsProbe(() => maybeAutoDisableBannedAccount({ connectionId: connId, ...PROBE_INPUT }));
+  assert.equal(readIsActive(connId), 1);
+});
+
+test("real-path permanent failure still disables (setting ON)", async () => {
+  const connId = await setupConnection();
+  await maybeAutoDisableBannedAccount({ connectionId: connId, ...PROBE_INPUT });
+  assert.equal(readIsActive(connId), 0);
+});
diff --git a/tests/unit/probe-gate-autodisable.test.ts b/tests/unit/probe-gate-autodisable.test.ts
new file mode 100644
index 0000000000..a4cb5755fb
--- /dev/null
+++ b/tests/unit/probe-gate-autodisable.test.ts
@@ -0,0 +1,294 @@
+import { test } from "node:test";
+import assert from "node:assert/strict";
+import fs from "node:fs";
+import os from "node:os";
+import path from "node:path";
+
+const TEST_DATA_DIR = fs.mkdtempSync(path.join(os.tmpdir(), "omniroute-probe-gate-"));
+process.env.DATA_DIR = TEST_DATA_DIR;
+
+const core = await import("../../src/lib/db/core.ts");
+const { createProviderConnection, deleteProviderConnection } =
+  await import("../../src/lib/db/providers.ts");
+const { runSingleModelTest, buildInternalChatRequest } =
+  await import("../../src/lib/api/modelTestRunner.ts");
+const chatRouteModule = await import("../../src/app/api/v1/chat/completions/route.ts");
+const postChatCompletion = chatRouteModule.POST;
+const { resetAllCircuitBreakers, getCircuitBreaker } =
+  await import("../../src/shared/utils/circuitBreaker.ts");
+const { invalidateDbCache } = await import("../../src/lib/db/readCache.ts");
+
+const originalFetch = globalThis.fetch;
+
+test.beforeEach(() => {
+  resetAllCircuitBreakers();
+  invalidateDbCache("connections");
+});
+
+test.after(() => {
+  globalThis.fetch = originalFetch;
+  core.resetDbInstance();
+  fs.rmSync(TEST_DATA_DIR, { recursive: true, force: true });
+});
+
+function readConnectionRow(connId: string) {
+  const db = core.getDbInstance() as unknown as {
+    prepare: (sql: string) => {
+      get: (id: string) => Record<string, unknown> | undefined;
+    };
+  };
+  return db
+    .prepare(
+      "SELECT is_active, test_status, rate_limited_until, last_error, refresh_token, access_token FROM provider_connections WHERE id = ?"
+    )
+    .get(connId);
+}
+
+async function createConnection(provider = "openai", extra: Record<string, unknown> = {}) {
+  const conn = await createProviderConnection({
+    provider,
+    authType: "apikey",
+    name: "probe-gate",
+    apiKey: "sk-probe-gate", // pragma: allowlist secret
+    isActive: true,
+    testStatus: "active",
+    ...extra,
+  });
+  return String((conn as { id: string }).id);
+}
+
+async function warmUp(connId: string): Promise<void> {
+  globalThis.fetch = async () =>
+    new Response(JSON.stringify({ choices: [{ message: { role: "assistant", content: "OK" } }] }), {
+      headers: { "content-type": "application/json" },
+    });
+  await runSingleModelTest({
+    providerId: "openai",
+    modelId: "gpt-4o",
+    connectionId: connId,
+    timeoutMs: 10_000,
+  });
+}
+
+function mockUpstream(status: number, message: string): void {
+  globalThis.fetch = async () =>
+    new Response(JSON.stringify({ error: { message } }), {
+      status,
+      headers: { "content-type": "application/json" },
+    });
+}
+
+const ASSERT_NO_COOLDOWN = (connId: string, label: string) => {
+  const row = readConnectionRow(connId);
+  assert.equal(row?.is_active, 1, `${label}: connection stays active`);
+  assert.notEqual(row?.test_status, "banned", `${label}: no terminal banned status`);
+  assert.notEqual(row?.test_status, "deactivated", `${label}: no deactivated status`);
+  assert.notEqual(row?.test_status, "credits_exhausted", `${label}: no credits_exhausted`);
+  assert.equal(row?.rate_limited_until, null, `${label}: no persisted cooldown`);
+  assert.ok(row?.last_error, `${label}: probe failure is recorded for visibility`);
+};
+
+test("GEO_BLOCKED (403 region) probe records but never persists the 24h cooldown", async () => {
+  const connId = await createConnection("gemini");
+  await warmUp(connId);
+  mockUpstream(403, "user location is not supported");
+  const result = await runSingleModelTest({
+    providerId: "gemini",
+    modelId: "gemini-2.5-flash",
+    connectionId: connId,
+    timeoutMs: 10_000,
+  });
+  assert.equal(result.status, "error");
+  ASSERT_NO_COOLDOWN(connId, "GEO probe");
+});
+
+test("QUOTA_EXHAUSTED (402) probe records but never writes the terminal credits state", async () => {
+  const connId = await createConnection();
+  await warmUp(connId);
+  mockUpstream(402, "billing cycle exhausted");
+  const result = await runSingleModelTest({
+    providerId: "openai",
+    modelId: "gpt-4o",
+    connectionId: connId,
+    timeoutMs: 10_000,
+  });
+  assert.equal(result.status, "error");
+  ASSERT_NO_COOLDOWN(connId, "QUOTA probe");
+});
+
+test("MODEL_NOT_FOUND (404) probe does not lock the model for real traffic", async () => {
+  const connId = await createConnection();
+  await warmUp(connId);
+  mockUpstream(404, "Model gpt-4o not found");
+  const failed = await runSingleModelTest({
+    providerId: "openai",
+    modelId: "gpt-4o",
+    connectionId: connId,
+    timeoutMs: 10_000,
+  });
+  assert.equal(failed.status, "error");
+  ASSERT_NO_COOLDOWN(connId, "404 probe");
+
+  globalThis.fetch = async () =>
+    new Response(JSON.stringify({ choices: [{ message: { role: "assistant", content: "OK" } }] }), {
+      headers: { "content-type": "application/json" },
+    });
+  const after = await runSingleModelTest({
+    providerId: "openai",
+    modelId: "gpt-4o",
+    connectionId: connId,
+    timeoutMs: 10_000,
+  });
+  assert.equal(after.status, "ok", "model lockout was not persisted by the probe");
+});
+
+test("401 probe never consumes the OAuth refresh token (no executor refresh call)", async () => {
+  let fetchCalls = 0;
+  const countingFetch = async (): Promise<Response> => {
+    fetchCalls += 1;
+    return new Response(JSON.stringify({ error: { message: "invalid token" } }), {
+      status: 401,
+      headers: { "content-type": "application/json" },
+    });
+  };
+  globalThis.fetch = countingFetch as typeof fetch;
+  const connId = await createConnection("github", {
+    authType: "oauth",
+    accessToken: "gh-probe-access",
+    refreshToken: "gh-probe-refresh",
+    providerSpecificData: { copilotToken: "gh-probe-copilot" },
+  });
+  const result = await runSingleModelTest({
+    providerId: "github",
+    modelId: "gpt-4o",
+    connectionId: connId,
+    timeoutMs: 10_000,
+  });
+  assert.equal(result.status, "error");
+  assert.equal(
+    fetchCalls,
+    1,
+    "exactly one upstream call — the refresh executor must never run for a probe"
+  );
+  const row = readConnectionRow(connId);
+  assert.equal(row?.refresh_token, "gh-probe-refresh", "refresh token untouched");
+  assert.equal(row?.access_token, "gh-probe-access", "access token untouched");
+  ASSERT_NO_COOLDOWN(connId, "401 probe");
+  // Remove this connection so the stale-token test below runs with exactly
+  // one github connection (the chatCore fallback would otherwise try the
+  // second github account, inflating its upstream fetch count).
+  await deleteProviderConnection(connId);
+});
+
+test("probe with a stale token never runs the PROACTIVE refresh (base.ts execute)", async () => {
+  let fetchCalls = 0;
+  globalThis.fetch = (async () => {
+    fetchCalls += 1;
+    return new Response(JSON.stringify({ error: { message: "invalid token" } }), {
+      status: 401,
+      headers: { "content-type": "application/json" },
+    });
+  }) as typeof fetch;
+  const connId = await createConnection("github", {
+    authType: "oauth",
+    accessToken: "gh-probe-access",
+    refreshToken: "gh-probe-refresh",
+    providerSpecificData: {
+      copilotToken: "gh-probe-copilot",
+      copilotTokenExpiresAt: new Date(Date.now() + 60_000).toISOString(),
+    },
+  });
+  const result = await runSingleModelTest({
+    providerId: "github",
+    modelId: "gpt-4o",
+    connectionId: connId,
+    timeoutMs: 10_000,
+  });
+  assert.equal(result.status, "error");
+  assert.equal(
+    fetchCalls,
+    1,
+    "stale-token probe must skip the proactive refresh rotation (no extra fetch)"
+  );
+  ASSERT_NO_COOLDOWN(connId, "stale-token probe");
+});
+
+test("gitlab stale-token probe never runs its own execute() refresh override", async () => {
+  let fetchCalls = 0;
+  globalThis.fetch = (async () => {
+    fetchCalls += 1;
+    return new Response(JSON.stringify({ error: { message: "invalid token" } }), {
+      status: 401,
+      headers: { "content-type": "application/json" },
+    });
+  }) as typeof fetch;
+  const connId = await createConnection("gitlab", {
+    authType: "oauth",
+    accessToken: "gl-probe-access",
+    refreshToken: "gl-probe-refresh",
+    expiresAt: new Date(Date.now() + 60_000).toISOString(),
+  });
+  const result = await runSingleModelTest({
+    providerId: "gitlab",
+    modelId: "gpt-4o",
+    connectionId: connId,
+    timeoutMs: 10_000,
+  });
+  assert.equal(result.status, "error");
+  assert.equal(
+    fetchCalls,
+    1,
+    "GitLabExecutor.execute must not consume a refresh rotation under a probe"
+  );
+  ASSERT_NO_COOLDOWN(connId, "gitlab stale-token probe");
+});
+
+test("codex 429 probe never runs the account-rotation failover (no persisted cooldown)", async () => {
+  const connId = await createConnection("codex");
+  await warmUp(connId);
+  mockUpstream(429, "rate limited");
+  const result = await runSingleModelTest({
+    providerId: "codex",
+    modelId: "gpt-5-codex",
+    connectionId: connId,
+    timeoutMs: 10_000,
+  });
+  assert.equal(result.status, "rate_limited");
+  ASSERT_NO_COOLDOWN(connId, "codex 429 probe");
+});
+
+test("upstream-timeout probe keeps the breaker and the connection intact", async () => {
+  const connId = await createConnection();
+  await warmUp(connId);
+
+  const timeoutError = new Error("upstream deadline exceeded");
+  timeoutError.name = "TimeoutError";
+  globalThis.fetch = async () => {
+    throw timeoutError;
+  };
+
+  const realRes = await postChatCompletion(
+    buildInternalChatRequest(
+      { model: "openai/gpt-4o", messages: [{ role: "user", content: "hi" }], stream: false },
+      new AbortController().signal,
+      connId
+    )
+  );
+  assert.notEqual(realRes.status, 200, "real timeout path exercised");
+  const breaker = getCircuitBreaker("openai");
+  assert.equal(breaker.failureCount, 0, "locally-tagged timeout never trips the breaker (design)");
+
+  const probe = await runSingleModelTest({
+    providerId: "openai",
+    modelId: "gpt-4o",
+    connectionId: connId,
+    timeoutMs: 10_000,
+  });
+  assert.equal(probe.status, "error");
+  assert.equal(breaker.failureCount, 0, "probe failure must not degrade the breaker");
+  assert.equal(
+    readConnectionRow(connId)?.is_active,
+    1,
+    "probe timeout keeps the connection active"
+  );
+});
diff --git a/tests/unit/probe-origin.test.ts b/tests/unit/probe-origin.test.ts
new file mode 100644
index 0000000000..6a5ee83a04
--- /dev/null
+++ b/tests/unit/probe-origin.test.ts
@@ -0,0 +1,38 @@
+import { test } from "node:test";
+import assert from "node:assert/strict";
+import Bottleneck from "bottleneck";
+
+const { runAsProbe, isProbeContext } = await import("../../src/shared/utils/probeOrigin.ts");
+
+test("runAsProbe propagates through nested async/await; false outside", async () => {
+  assert.equal(isProbeContext(), false);
+  await runAsProbe(async () => {
+    assert.equal(isProbeContext(), true);
+    await Promise.resolve();
+    const inner = async () => {
+      await Promise.resolve();
+      return isProbeContext();
+    };
+    assert.equal(await inner(), true);
+    await new Promise((r) => setTimeout(r, 5));
+    assert.equal(isProbeContext(), true);
+  });
+  assert.equal(isProbeContext(), false);
+});
+
+test("queued scheduler job wrapped in runAsProbe keeps the probe context", async () => {
+  const limiter = new Bottleneck({ maxConcurrent: 1, minTime: 50 });
+  let insideQueuedJob: boolean | null = null;
+  // Schedule job 1 WITHOUT awaiting it so job 2 really queues behind it
+  // (maxConcurrent 1 + minTime 50) — the queued job must execute with the
+  // probe context established at scheduling time.
+  const job1 = limiter.schedule(() => new Promise((r) => setTimeout(r, 30)));
+  const job2 = limiter.schedule(() =>
+    runAsProbe(() => {
+      insideQueuedJob = isProbeContext();
+      return Promise.resolve();
+    })
+  );
+  await Promise.all([job1, job2]);
+  assert.equal(insideQueuedJob, true);
+});
diff --git a/tests/unit/probe-policy.test.ts b/tests/unit/probe-policy.test.ts
new file mode 100644
index 0000000000..bed1fc6f55
--- /dev/null
+++ b/tests/unit/probe-policy.test.ts
@@ -0,0 +1,61 @@
+import { test } from "node:test";
+import assert from "node:assert/strict";
+import fs from "node:fs";
+import os from "node:os";
+import path from "node:path";
+
+const TEST_DATA_DIR = fs.mkdtempSync(path.join(os.tmpdir(), "omniroute-probe-policy-"));
+process.env.DATA_DIR = TEST_DATA_DIR;
+
+const core = await import("../../src/lib/db/core.ts");
+const settingsDb = await import("../../src/lib/db/settings.ts");
+const { runAsProbe, shouldIsolateProbeFailures, isProbeContext } =
+  await import("../../src/shared/utils/probeOrigin.ts");
+
+test.after(() => {
+  delete process.env.PROBE_CAN_DISABLE;
+  core.resetDbInstance();
+  fs.rmSync(TEST_DATA_DIR, { recursive: true, force: true });
+});
+
+test("outside a probe context the decision is always false (real path)", async () => {
+  await settingsDb.updateSettings({ probeCanDisable: true });
+  assert.equal(await shouldIsolateProbeFailures(), false);
+});
+
+test("probe + default settings => isolation ON (probe never disables)", async () => {
+  await settingsDb.updateSettings({ probeCanDisable: false });
+  await runAsProbe(async () => {
+    assert.equal(await shouldIsolateProbeFailures(), true);
+  });
+});
+
+test("probe + opt-in setting probeCanDisable => isolation OFF (historical behavior)", async () => {
+  await settingsDb.updateSettings({ probeCanDisable: true });
+  await runAsProbe(async () => {
+    assert.equal(await shouldIsolateProbeFailures(), false);
+  });
+});
+
+test("probe + env feature flag PROBE_CAN_DISABLE=true => isolation OFF", async () => {
+  process.env.PROBE_CAN_DISABLE = "true";
+  await settingsDb.updateSettings({ probeCanDisable: false });
+  await runAsProbe(async () => {
+    assert.equal(await shouldIsolateProbeFailures(), false);
+  });
+});
+
+test("probe + flag false + setting true => setting wins (flag must not re-enable isolation)", async () => {
+  process.env.PROBE_CAN_DISABLE = "false";
+  await settingsDb.updateSettings({ probeCanDisable: true });
+  await runAsProbe(async () => {
+    assert.equal(await shouldIsolateProbeFailures(), false);
+  });
+});
+
+test("probe context propagation is still pinned (policy uses the same gate)", async () => {
+  assert.equal(isProbeContext(), false);
+  await runAsProbe(async () => {
+    assert.equal(isProbeContext(), true);
+  });
+});
diff --git a/tests/unit/probe-production-path.test.ts b/tests/unit/probe-production-path.test.ts
new file mode 100644
index 0000000000..3b099b99dc
--- /dev/null
+++ b/tests/unit/probe-production-path.test.ts
@@ -0,0 +1,58 @@
+import { test } from "node:test";
+import assert from "node:assert/strict";
+import fs from "node:fs";
+import os from "node:os";
+import path from "node:path";
+
+const TEST_DATA_DIR = fs.mkdtempSync(path.join(os.tmpdir(), "omniroute-probe-prodpath-"));
+process.env.DATA_DIR = TEST_DATA_DIR;
+
+const core = await import("../../src/lib/db/core.ts");
+const settingsDb = await import("../../src/lib/db/settings.ts");
+const { createProviderConnection } = await import("../../src/lib/db/providers.ts");
+const { markAccountUnavailable } = await import("../../src/sse/services/auth.ts");
+
+test.after(() => {
+  core.resetDbInstance();
+  fs.rmSync(TEST_DATA_DIR, { recursive: true, force: true });
+});
+
+function readConnectionRow(connId: string) {
+  const db = core.getDbInstance() as unknown as {
+    prepare: (sql: string) => {
+      get: (id: string) =>
+        | {
+            is_active: unknown;
+            test_status: unknown;
+            rate_limited_until: unknown;
+          }
+        | undefined;
+    };
+  };
+  return db
+    .prepare(
+      "SELECT is_active, test_status, rate_limited_until FROM provider_connections WHERE id = ?"
+    )
+    .get(connId);
+}
+
+test("real-path permanent failure keeps the full production behavior", async () => {
+  await settingsDb.updateSettings({ autoDisableBannedAccounts: true });
+  const conn = await createProviderConnection({
+    provider: "openai",
+    authType: "apikey",
+    name: "probe-prodpath",
+    apiKey: "sk-probe-prodpath", // pragma: allowlist secret
+    isActive: true,
+    testStatus: "active",
+  });
+  const connId = String((conn as { id: string }).id);
+
+  const res = await markAccountUnavailable(connId, 403, "this account is deactivated", "openai");
+  assert.equal(res.shouldFallback, true);
+
+  const row = readConnectionRow(connId);
+  assert.equal(row?.is_active, 0, "is_active flipped off (auto-disable, setting ON)");
+  assert.equal(row?.test_status, "banned", "terminal status written");
+  assert.equal(row?.rate_limited_until, null, "no persisted cooldown on the terminal path");
+});
diff --git a/tests/unit/probe-testall-isolation.test.ts b/tests/unit/probe-testall-isolation.test.ts
new file mode 100644
index 0000000000..40016fec82
--- /dev/null
+++ b/tests/unit/probe-testall-isolation.test.ts
@@ -0,0 +1,176 @@
+import { test } from "node:test";
+import assert from "node:assert/strict";
+import fs from "node:fs";
+import os from "node:os";
+import path from "node:path";
+
+const TEST_DATA_DIR = fs.mkdtempSync(path.join(os.tmpdir(), "omniroute-probe-testall-"));
+process.env.DATA_DIR = TEST_DATA_DIR;
+
+const core = await import("../../src/lib/db/core.ts");
+const { createProviderConnection } = await import("../../src/lib/db/providers.ts");
+const { runSingleModelTest } = await import("../../src/lib/api/modelTestRunner.ts");
+const { resetAllCircuitBreakers } = await import("../../src/shared/utils/circuitBreaker.ts");
+const { invalidateDbCache } = await import("../../src/lib/db/readCache.ts");
+const { refreshConnectionRateLimits, enableRateLimitProtection } =
+  await import("@omniroute/open-sse/services/rateLimitManager.ts");
+
+const originalFetch = globalThis.fetch;
+
+// A test-all 403 can also open the provider circuit breaker and stale the
+// 5s connections read cache (rawConnectionsCache) — either would
+// short-circuit the NEXT tests before chatCore, a false positive for the
+// isolation asserts. Reset both before every test.
+test.beforeEach(() => {
+  resetAllCircuitBreakers();
+  invalidateDbCache("connections");
+});
+
+test.after(() => {
+  globalThis.fetch = originalFetch;
+  core.resetDbInstance();
+  fs.rmSync(TEST_DATA_DIR, { recursive: true, force: true });
+});
+
+function readConnectionRow(connId: string) {
+  const db = core.getDbInstance() as unknown as {
+    prepare: (sql: string) => {
+      get: (id: string) =>
+        | {
+            is_active: unknown;
+            test_status: unknown;
+            rate_limited_until: unknown;
+            last_error: unknown;
+          }
+        | undefined;
+    };
+  };
+  return db
+    .prepare(
+      "SELECT is_active, test_status, rate_limited_until, last_error FROM provider_connections WHERE id = ?"
+    )
+    .get(connId);
+}
+
+async function createConnection(): Promise<string> {
+  const conn = await createProviderConnection({
+    provider: "openai",
+    authType: "apikey",
+    name: "probe-testall",
+    apiKey: "sk-probe-testall", // pragma: allowlist secret
+    isActive: true,
+    testStatus: "active",
+  });
+  return String((conn as { id: string }).id);
+}
+
+// Warm up the chat-completions pipeline (SSE translators, compression
+// settings, etc. lazy-init on the first real request in a process) with a
+// fast success mock, mirroring model-test-runner.test.ts.
+async function warmUp(connId: string): Promise<void> {
+  globalThis.fetch = async () =>
+    new Response(JSON.stringify({ choices: [{ message: { role: "assistant", content: "OK" } }] }), {
+      headers: { "content-type": "application/json" },
+    });
+  await runSingleModelTest({
+    providerId: "openai",
+    modelId: "gpt-4o",
+    connectionId: connId,
+    timeoutMs: 10_000,
+  });
+}
+
+async function mockUpstream(status: number, message: string): Promise<void> {
+  globalThis.fetch = async () =>
+    new Response(JSON.stringify({ error: { message } }), {
+      status,
+      headers: { "content-type": "application/json" },
+    });
+}
+
+const ASSERT_ISOLATED = (connId: string) => {
+  const row = readConnectionRow(connId);
+  assert.equal(row?.is_active, 1, "connection stays active after a probe failure");
+  assert.notEqual(row?.test_status, "banned", "no terminal banned status from a probe");
+  assert.notEqual(row?.test_status, "deactivated", "no deactivated status from a probe");
+  assert.equal(row?.rate_limited_until, null, "no cooldown persisted by a probe");
+  assert.ok(row?.last_error, "probe failure is recorded for visibility");
+};
+
+test("test-all FORBIDDEN failure (Sentinel) does not deactivate the connection", async () => {
+  const connId = await createConnection();
+  await warmUp(connId);
+  await mockUpstream(403, "SENTINEL_BLOCKED");
+  const result = await runSingleModelTest({
+    providerId: "openai",
+    modelId: "gpt-4o",
+    connectionId: connId,
+    timeoutMs: 10_000,
+  });
+  assert.equal(result.status, "error");
+  ASSERT_ISOLATED(connId);
+});
+
+test("test-all ACCOUNT_DEACTIVATED failure does not deactivate the connection", async () => {
+  const connId = await createConnection();
+  await warmUp(connId);
+  await mockUpstream(403, "this account is deactivated");
+  const result = await runSingleModelTest({
+    providerId: "openai",
+    modelId: "gpt-4o",
+    connectionId: connId,
+    timeoutMs: 10_000,
+  });
+  assert.equal(result.status, "error");
+  ASSERT_ISOLATED(connId);
+});
+
+test("queued (rate-limited) test-all failure stays isolated", async () => {
+  const connId = await createConnection();
+  await warmUp(connId);
+  // Rate-limit protection is OFF by default for test connections (empty
+  // enabledConnections — withRateLimit:537-540 would short-circuit directly,
+  // a false positive on the inner wrapper). Enable it so the calls really
+  // go through the Bottleneck limiter.
+  enableRateLimitProtection(connId);
+  // minTime 200 forces the 2nd job to wait behind the 1st — the queued job
+  // must run inside the probe context (inner wrapper in withRateLimit);
+  // without it, ASSERT_ISOLATED goes red.
+  refreshConnectionRateLimits(connId, { minTime: 200 });
+  await mockUpstream(403, "SENTINEL_BLOCKED");
+  await runSingleModelTest({
+    providerId: "openai",
+    modelId: "gpt-4o",
+    connectionId: connId,
+    timeoutMs: 10_000,
+  });
+  await runSingleModelTest({
+    providerId: "openai",
+    modelId: "gpt-4o",
+    connectionId: connId,
+    timeoutMs: 10_000,
+  });
+  ASSERT_ISOLATED(connId);
+});
+
+test("RESTORE: probe with opt-in probeCanDisable=true deactivates like real traffic", async () => {
+  const settingsDb = await import("../../src/lib/db/settings.ts");
+  await settingsDb.updateSettings({ probeCanDisable: true });
+  try {
+    const connId = await createConnection();
+    await warmUp(connId);
+    await mockUpstream(403, "SENTINEL_BLOCKED");
+    const result = await runSingleModelTest({
+      providerId: "openai",
+      modelId: "gpt-4o",
+      connectionId: connId,
+      timeoutMs: 10_000,
+    });
+    assert.equal(result.status, "error");
+    const row = readConnectionRow(connId);
+    assert.equal(row?.is_active, 0, "opt-in restores historical behavior: probe deactivates");
+    assert.equal(row?.test_status, "banned", "terminal banned status restored for probe");
+  } finally {
+    await settingsDb.updateSettings({ probeCanDisable: false });
+  }
+});