diff --git a/docs/project-roadmap.md b/docs/project-roadmap.md
index a07dcae8..f439fae7 100644
--- a/docs/project-roadmap.md
+++ b/docs/project-roadmap.md
@@ -1,6 +1,6 @@
 # CCS Project Roadmap
 
-Last Updated: 2026-04-21
+Last Updated: 2026-04-28
 
 Forward-looking roadmap documenting current priorities, GitHub issues, and future feature plans.
 
@@ -41,6 +41,7 @@ All major modularization work is complete. The codebase evolved from monolithic
 
 ### Recent Fixes
 
+- **2026-04-28**: **#1115** CCS now exposes upstream CLIProxy session affinity as a first-class local managed setting. Users can inspect and toggle local `session-affinity` plus TTL from `ccs cliproxy routing affinity`, from the `/cliproxy` dashboard routing card, and through the local dashboard API. The generated local CLIProxy config now persists `routing.session-affinity` and `routing.session-affinity-ttl`, help/copy explains that CLIProxy prefers explicit session or thread identifiers before falling back to prompt-history hashing, and remote session-affinity management stays explicitly unsupported until upstream management APIs expose more than `routing.strategy`.
 - **2026-04-24**: **#1065** Local CLIProxy Plus is available again as an explicit opt-in backend through the community-maintained `kaitranntt/CLIProxyAPIPlus` fork. CCS keeps `original` as the default backend, no longer downgrades saved `backend: plus` configs to `original`, updates Plus release lookups to the maintained fork, and documents Plus as a targeted path for plus-only providers.
 - **2026-04-21**: CLIProxy quota failover now quarantines exhausted Claude and Antigravity accounts out of live rotation when a healthy fallback exists. CCS persists those quota-triggered pauses across launches, automatically resumes them after the configured cooldown window, and deliberately avoids auto-pausing the last available account so single-account setups still degrade gracefully instead of hard-locking themselves.
 - **2026-04-20**: **#1051** Browser automation now defaults safe-off for new installs and upgrades that do not already carry explicit browser settings. CCS changes both Claude Browser Attach and Codex Browser Tools to start with `enabled: false` and `policy: manual`, normalizes missing browser policies on upgrade back to `manual`, preserves explicit existing enablement, and updates status/help/docs so browser tooling is never implied to auto-expose unless users opt in.
diff --git a/src/cliproxy/config/generator.ts b/src/cliproxy/config/generator.ts
index 43ce4672..926bdc9e 100644
--- a/src/cliproxy/config/generator.ts
+++ b/src/cliproxy/config/generator.ts
@@ -40,8 +40,9 @@ export const CCS_CONTROL_PANEL_SECRET = 'ccs';
  * v15: Prune stale generated Antigravity Gemini preview aliases during regeneration
  * v16: Narrow stale Gemini alias cleanup to broad multi-version guessed ranges
  * v17: Persist routing.strategy from CCS unified config
+ * v18: Persist routing.session-affinity and routing.session-affinity-ttl from CCS unified config
  */
-export const CLIPROXY_CONFIG_VERSION = 17;
+export const CLIPROXY_CONFIG_VERSION = 18;
 
 interface RegenerateConfigOptions {
   configPath?: string;
@@ -132,6 +133,15 @@ function getRoutingStrategy(): 'round-robin' | 'fill-first' {
   return config.cliproxy?.routing?.strategy === 'fill-first' ? 'fill-first' : 'round-robin';
 }
 
+function getSessionAffinityEnabled(): boolean {
+  return loadOrCreateUnifiedConfig().cliproxy?.routing?.session_affinity ?? false;
+}
+
+function getSessionAffinityTtl(): string {
+  const ttl = loadOrCreateUnifiedConfig().cliproxy?.routing?.session_affinity_ttl?.trim();
+  return ttl || '1h';
+}
+
 function sanitizeYamlScalar(rawValue: string): string {
   const trimmed = rawValue.trim();
   if (
@@ -552,6 +562,8 @@ function generateUnifiedConfigContent(
   // Get logging settings from user config (disabled by default)
   const { loggingToFile, requestLog } = getLoggingSettings();
   const routingStrategy = getRoutingStrategy();
+  const sessionAffinityEnabled = getSessionAffinityEnabled();
+  const sessionAffinityTtl = getSessionAffinityTtl();
 
   // Get effective auth tokens (respects user customization)
   const effectiveApiKey = getEffectiveApiKey();
@@ -627,6 +639,8 @@ quota-exceeded:
 # Credential selection strategy when multiple matching accounts are available
 routing:
   strategy: ${routingStrategy}
+  session-affinity: ${sessionAffinityEnabled}
+  session-affinity-ttl: "${sessionAffinityTtl}"
 
 # =============================================================================
 # Authentication
diff --git a/src/cliproxy/routing-strategy.ts b/src/cliproxy/routing-strategy.ts
index ff621a9b..038e7dea 100644
--- a/src/cliproxy/routing-strategy.ts
+++ b/src/cliproxy/routing-strategy.ts
@@ -9,6 +9,11 @@ import {
 import type { CliproxyRoutingStrategy } from './types';
 
 export const DEFAULT_CLIPROXY_ROUTING_STRATEGY: CliproxyRoutingStrategy = 'round-robin';
+export const DEFAULT_CLIPROXY_SESSION_AFFINITY_ENABLED = false;
+export const DEFAULT_CLIPROXY_SESSION_AFFINITY_TTL = '1h';
+
+const GO_DURATION_SEGMENT = String.raw`(?:\d+(?:\.\d+)?(?:ns|us|µs|μs|ms|s|m|h))`;
+const GO_DURATION_PATTERN = new RegExp(`^${GO_DURATION_SEGMENT}+$`);
 
 export interface CliproxyRoutingState {
   strategy: CliproxyRoutingStrategy;
@@ -22,6 +27,25 @@ export interface CliproxyRoutingApplyResult extends CliproxyRoutingState {
   applied: 'live' | 'live-and-config' | 'config-only';
 }
 
+export interface CliproxySessionAffinitySettings {
+  enabled: boolean;
+  ttl?: string;
+}
+
+export interface CliproxySessionAffinityState {
+  enabled?: boolean;
+  ttl?: string;
+  source: 'config' | 'unsupported';
+  target: 'local' | 'remote';
+  reachable: boolean;
+  manageable: boolean;
+  message?: string;
+}
+
+export interface CliproxySessionAffinityApplyResult extends CliproxySessionAffinityState {
+  applied: 'config-only' | 'unsupported';
+}
+
 export function normalizeCliproxyRoutingStrategy(value: unknown): CliproxyRoutingStrategy | null {
   if (typeof value !== 'string') {
     return null;
@@ -41,6 +65,47 @@ export function normalizeCliproxyRoutingStrategy(value: unknown): CliproxyRoutin
   }
 }
 
+export function normalizeCliproxySessionAffinityEnabled(value: unknown): boolean | null {
+  if (typeof value === 'boolean') {
+    return value;
+  }
+  if (typeof value !== 'string') {
+    return null;
+  }
+
+  switch (value.trim().toLowerCase()) {
+    case 'true':
+    case '1':
+    case 'yes':
+    case 'on':
+    case 'enable':
+    case 'enabled':
+      return true;
+    case 'false':
+    case '0':
+    case 'no':
+    case 'off':
+    case 'disable':
+    case 'disabled':
+      return false;
+    default:
+      return null;
+  }
+}
+
+export function normalizeCliproxySessionAffinityTtl(value: unknown): string | null {
+  if (typeof value !== 'string') {
+    return null;
+  }
+
+  const trimmed = value.trim();
+  if (!trimmed || !GO_DURATION_PATTERN.test(trimmed)) {
+    return null;
+  }
+
+  return trimmed;
+}
+
 export function getConfiguredCliproxyRoutingStrategy(): CliproxyRoutingStrategy {
   return (
     normalizeCliproxyRoutingStrategy(loadOrCreateUnifiedConfig().cliproxy?.routing?.strategy) ??
@@ -48,6 +113,18 @@ export function getConfiguredCliproxyRoutingStrategy(): CliproxyRoutingStrategy
   );
 }
 
+export function getConfiguredCliproxySessionAffinitySettings(): Required<CliproxySessionAffinitySettings> {
+  const routing = loadOrCreateUnifiedConfig().cliproxy?.routing;
+  return {
+    enabled:
+      normalizeCliproxySessionAffinityEnabled(routing?.session_affinity) ??
+      DEFAULT_CLIPROXY_SESSION_AFFINITY_ENABLED,
+    ttl:
+      normalizeCliproxySessionAffinityTtl(routing?.session_affinity_ttl) ??
+      DEFAULT_CLIPROXY_SESSION_AFFINITY_TTL,
+  };
+}
+
 export async function fetchLiveCliproxyRoutingStrategy(): Promise<CliproxyRoutingStrategy> {
   const response = await fetchCliproxyRoutingResponse(getCliproxyRoutingTarget(), 'GET');
   if (!response.ok) {
@@ -95,6 +172,36 @@ export async function readCliproxyRoutingState(): Promise<CliproxyRoutingState>
   }
 }
 
+export async function readCliproxySessionAffinityState(): Promise<CliproxySessionAffinityState> {
+  const target = getCliproxyRoutingTarget();
+
+  if (target.isRemote) {
+    return {
+      source: 'unsupported',
+      target: 'remote',
+      reachable: true,
+      manageable: false,
+      message:
+        'Remote session-affinity management is not supported from CCS yet because upstream management APIs only expose routing.strategy.',
+    };
+  }
+
+  const settings = getConfiguredCliproxySessionAffinitySettings();
+  const reachable = await isLocalCliproxyReachable();
+
+  return {
+    enabled: settings.enabled,
+    ttl: settings.ttl,
+    source: 'config',
+    target: 'local',
+    reachable,
+    manageable: true,
+    message: reachable
+      ? 'CCS manages session affinity through the generated local CLIProxy config. Running local CLIProxy should hot-reload this setting.'
+      : 'Local CLIProxy is not reachable. Showing the saved local startup default.',
+  };
+}
+
 export async function applyCliproxyRoutingStrategy(
   strategy: CliproxyRoutingStrategy
 ): Promise<CliproxyRoutingApplyResult> {
@@ -116,7 +223,7 @@ export async function applyCliproxyRoutingStrategy(
 
   mutateUnifiedConfig((config) => {
     if (config.cliproxy) {
-      config.cliproxy.routing = { strategy };
+      config.cliproxy.routing = { ...config.cliproxy.routing, strategy };
     }
   });
   regenerateConfig(target.port, { configPath, authDir });
@@ -143,6 +250,56 @@ export async function applyCliproxyRoutingStrategy(
   }
 }
 
+export async function applyCliproxySessionAffinitySettings(
+  settings: CliproxySessionAffinitySettings
+): Promise<CliproxySessionAffinityApplyResult> {
+  const target = getCliproxyRoutingTarget();
+  if (target.isRemote) {
+    return {
+      source: 'unsupported',
+      target: 'remote',
+      reachable: true,
+      manageable: false,
+      applied: 'unsupported',
+      message:
+        'Remote session-affinity management is not supported from CCS yet because upstream management APIs only expose routing.strategy.',
+    };
+  }
+
+  const configPath = getConfigPathForPort(target.port);
+  const authDir = getAuthDir();
+  const current = getConfiguredCliproxySessionAffinitySettings();
+  const ttl =
+    normalizeCliproxySessionAffinityTtl(settings.ttl) ??
+    current.ttl ??
+    DEFAULT_CLIPROXY_SESSION_AFFINITY_TTL;
+
+  mutateUnifiedConfig((config) => {
+    if (config.cliproxy) {
+      config.cliproxy.routing = {
+        ...config.cliproxy.routing,
+        session_affinity: settings.enabled,
+        session_affinity_ttl: ttl,
+      };
+    }
+  });
+  regenerateConfig(target.port, { configPath, authDir });
+
+  const reachable = await isLocalCliproxyReachable();
+  return {
+    enabled: settings.enabled,
+    ttl,
+    source: 'config',
+    target: 'local',
+    reachable,
+    manageable: true,
+    applied: 'config-only',
+    message: reachable
+      ? 'Saved the local startup default. Running local CLIProxy may hot-reload the session-affinity setting, but CCS does not verify live selector state yet.'
+      : 'Saved the local startup default. It will apply the next time local CLIProxy starts.',
+  };
+}
+
 async function updateLiveCliproxyRoutingStrategy(strategy: CliproxyRoutingStrategy): Promise<void> {
   const response = await fetchCliproxyRoutingResponse(getCliproxyRoutingTarget(), 'PUT', {
     value: strategy,
@@ -156,3 +313,12 @@ async function updateLiveCliproxyRoutingStrategy(strategy: CliproxyRoutingStrate
     );
   }
 }
+
+async function isLocalCliproxyReachable(): Promise<boolean> {
+  try {
+    await fetchLiveCliproxyRoutingStrategy();
+    return true;
+  } catch {
+    return false;
+  }
+}
diff --git a/src/cliproxy/types.ts b/src/cliproxy/types.ts
index abf00136..2abd2052 100644
--- a/src/cliproxy/types.ts
+++ b/src/cliproxy/types.ts
@@ -194,6 +194,9 @@ export interface CLIProxyConfig {
   debug: boolean;
   routing?: {
     strategy?: CliproxyRoutingStrategy;
+    'session-affinity'?: boolean;
+    'session-affinity-ttl'?: string;
+    'claude-code-session-affinity'?: boolean;
   };
   'gemini-api-key'?: Array<{
     'api-key': string;
diff --git a/src/commands/cliproxy/help-subcommand.ts b/src/commands/cliproxy/help-subcommand.ts
index ccecad99..f349be7e 100644
--- a/src/commands/cliproxy/help-subcommand.ts
+++ b/src/commands/cliproxy/help-subcommand.ts
@@ -59,8 +59,10 @@ export async function showHelp(): Promise<void> {
         ['quota', 'Show quota status for all providers (Codex/Claude include 5h + weekly reset)'],
         ['quota --provider <name>', `Filter by provider (${QUOTA_PROVIDER_HELP_TEXT})`],
         ['routing', 'Show current routing strategy and manual guidance'],
-        ['routing explain', 'Explain round-robin vs fill-first'],
+        ['routing explain', 'Explain strategy vs session-affinity and how sessions are recognized'],
         ['routing set <mode>', 'Explicitly set round-robin or fill-first'],
+        ['routing affinity', 'Show local session-affinity status and TTL'],
+        ['routing affinity <on|off> [--ttl <duration>]', 'Toggle local session-affinity settings'],
       ],
     ],
     [
diff --git a/src/commands/cliproxy/index.ts b/src/commands/cliproxy/index.ts
index b7de5ebb..b269371b 100644
--- a/src/commands/cliproxy/index.ts
+++ b/src/commands/cliproxy/index.ts
@@ -34,7 +34,13 @@ import {
 } from './proxy-lifecycle-subcommand';
 import { showStatus, handleInstallVersion, handleInstallLatest } from './install-subcommand';
 import { showHelp } from './help-subcommand';
-import { handleRoutingStatus, handleRoutingExplain, handleRoutingSet } from './routing-subcommand';
+import {
+  handleRoutingStatus,
+  handleRoutingExplain,
+  handleRoutingSet,
+  handleRoutingAffinityStatus,
+  handleRoutingAffinitySet,
+} from './routing-subcommand';
 import {
   handleCatalogStatus,
   handleCatalogRefresh,
@@ -189,6 +195,14 @@ export async function handleCliproxyCommand(args: string[]): Promise<void> {
       await handleRoutingExplain();
       return;
     }
+    if (subcommand === 'affinity') {
+      if (remainingArgs[2]) {
+        await handleRoutingAffinitySet(remainingArgs.slice(2));
+        return;
+      }
+      await handleRoutingAffinityStatus();
+      return;
+    }
     await handleRoutingStatus();
     return;
   }
diff --git a/src/commands/cliproxy/routing-subcommand.ts b/src/commands/cliproxy/routing-subcommand.ts
index f78aed21..326a9249 100644
--- a/src/commands/cliproxy/routing-subcommand.ts
+++ b/src/commands/cliproxy/routing-subcommand.ts
@@ -1,8 +1,13 @@
 import { initUI, header, subheader, color, dim, ok, fail, infoBox } from '../../utils/ui';
+import { extractOption } from '../arg-extractor';
 import {
   applyCliproxyRoutingStrategy,
+  applyCliproxySessionAffinitySettings,
   normalizeCliproxyRoutingStrategy,
+  normalizeCliproxySessionAffinityEnabled,
+  normalizeCliproxySessionAffinityTtl,
   readCliproxyRoutingState,
+  readCliproxySessionAffinityState,
 } from '../../cliproxy/routing-strategy';
 
 function printStrategyGuide(): void {
@@ -23,13 +28,52 @@ function printStrategyGuide(): void {
   console.log('');
 }
 
+function printSessionAffinityGuide(): void {
+  console.log(subheader('Session Affinity:'));
+  console.log(
+    `  ${color('session-affinity off', 'command')} Each request follows the base routing strategy.`
+  );
+  console.log(`  ${dim('    Best when you want pure proxy-wide balancing behavior.')}`);
+  console.log('');
+  console.log(
+    `  ${color('session-affinity on', 'command')} Keep one conversation pinned to the same account when possible.`
+  );
+  console.log(
+    `  ${dim('    Best when you want stronger prompt-cache locality for a single conversation.')}`
+  );
+  console.log('');
+}
+
+function printSessionRecognitionGuide(): void {
+  console.log(subheader('How CLIProxy Knows A Session Is New:'));
+  console.log(
+    `  ${dim('  CLIProxy prefers explicit session or thread identifiers when clients send them.')}`
+  );
+  console.log(
+    `  ${dim('  Common examples: Claude session UUIDs, X-Session-ID, or provider-specific thread ids.')}`
+  );
+  console.log(
+    `  ${dim('  If no explicit identifier is present, it can fall back to fields such as metadata.user_id or conversation_id.')}`
+  );
+  console.log(
+    `  ${dim('  Last resort: it derives a stable key from the opening prompt history.')}`
+  );
+  console.log(
+    `  ${dim('  Exact precedence can vary by upstream backend/runtime version, so CCS does not promise one universal order.')}`
+  );
+  console.log('');
+}
+
 export async function handleRoutingStatus(): Promise<void> {
   await initUI();
   console.log('');
   console.log(header('CLIProxy Routing Strategy'));
   console.log('');
 
-  const state = await readCliproxyRoutingState();
+  const [state, sessionAffinity] = await Promise.all([
+    readCliproxyRoutingState(),
+    readCliproxySessionAffinityState(),
+  ]);
   console.log(`  Current: ${color(state.strategy, 'command')}`);
   console.log(`  Target:  ${color(state.target, 'info')}`);
   console.log(
@@ -39,8 +83,28 @@ export async function handleRoutingStatus(): Promise<void> {
     console.log('');
     console.log(infoBox(state.message, state.reachable ? 'INFO' : 'WARNING'));
   }
+  console.log(
+    `  Session Affinity: ${
+      sessionAffinity.manageable
+        ? color(sessionAffinity.enabled ? 'on' : 'off', 'command')
+        : color('unsupported', 'warning')
+    }`
+  );
+  if (sessionAffinity.ttl) {
+    console.log(`  Affinity TTL: ${color(sessionAffinity.ttl, 'info')}`);
+  }
+  if (sessionAffinity.message) {
+    console.log('');
+    console.log(
+      infoBox(
+        sessionAffinity.message,
+        sessionAffinity.manageable && sessionAffinity.reachable ? 'INFO' : 'WARNING'
+      )
+    );
+  }
   console.log('');
   printStrategyGuide();
+  printSessionAffinityGuide();
 }
 
 export async function handleRoutingExplain(): Promise<void> {
@@ -49,6 +113,8 @@ export async function handleRoutingExplain(): Promise<void> {
   console.log(header('CLIProxy Routing Guide'));
   console.log('');
   printStrategyGuide();
+  printSessionAffinityGuide();
+  printSessionRecognitionGuide();
 }
 
 export async function handleRoutingSet(args: string[]): Promise<void> {
@@ -78,3 +144,78 @@ export async function handleRoutingSet(args: string[]): Promise<void> {
   }
   console.log('');
 }
+
+export async function handleRoutingAffinityStatus(): Promise<void> {
+  await initUI();
+  console.log('');
+  console.log(header('CLIProxy Session Affinity'));
+  console.log('');
+
+  const state = await readCliproxySessionAffinityState();
+  if (!state.manageable) {
+    console.log(`  Status: ${color('unsupported', 'warning')}`);
+  } else {
+    console.log(`  Status: ${color(state.enabled ? 'on' : 'off', 'command')}`);
+  }
+  console.log(`  Target: ${color(state.target, 'info')}`);
+  if (state.ttl) {
+    console.log(`  TTL:    ${color(state.ttl, 'info')}`);
+  }
+  if (state.message) {
+    console.log('');
+    console.log(infoBox(state.message, state.manageable && state.reachable ? 'INFO' : 'WARNING'));
+  }
+  console.log('');
+  printSessionAffinityGuide();
+  printSessionRecognitionGuide();
+}
+
+export async function handleRoutingAffinitySet(args: string[]): Promise<void> {
+  const requested = normalizeCliproxySessionAffinityEnabled(args[0]);
+  const extractedTtl = extractOption(args.slice(1), ['--ttl']);
+  const ttl: string | undefined =
+    extractedTtl.found && !extractedTtl.missingValue
+      ? (normalizeCliproxySessionAffinityTtl(extractedTtl.value) ?? undefined)
+      : undefined;
+
+  if (requested === null || extractedTtl.missingValue || (extractedTtl.found && !ttl)) {
+    await initUI();
+    console.log('');
+    console.log(
+      fail('Invalid session affinity command. Use: routing affinity <on|off> [--ttl 1h]')
+    );
+    console.log('');
+    printSessionAffinityGuide();
+    console.log(`  ${dim('Accepted TTL examples: 30m, 1h, 2h30m')}`);
+    console.log('');
+    process.exitCode = 1;
+    return;
+  }
+
+  await initUI();
+  console.log('');
+  console.log(header('Update CLIProxy Session Affinity'));
+  console.log('');
+
+  const result = await applyCliproxySessionAffinitySettings({
+    enabled: requested,
+    ttl,
+  });
+
+  if (!result.manageable) {
+    console.log(fail(result.message || 'Session affinity is not supported for this target.'));
+    console.log('');
+    return;
+  }
+
+  console.log(ok(`Session affinity ${requested ? 'enabled' : 'disabled'}`));
+  if (result.ttl) {
+    console.log(`  TTL:     ${color(result.ttl, 'info')}`);
+  }
+  console.log(`  Applied: ${color(result.applied, 'info')}`);
+  if (result.message) {
+    console.log('');
+    console.log(infoBox(result.message, result.reachable ? 'SUCCESS' : 'INFO'));
+  }
+  console.log('');
+}
diff --git a/src/commands/completion-backend.ts b/src/commands/completion-backend.ts
index c968c720..a18ff712 100644
--- a/src/commands/completion-backend.ts
+++ b/src/commands/completion-backend.ts
@@ -171,7 +171,10 @@ function getSuggestionsForCommand(tokensBeforeCurrent: string[]): CompletionSugg
         if (lastToken === 'set') {
           return completeSubcommands(['round-robin', 'fill-first']);
         }
-        return completeSubcommands(['set', 'explain']);
+        if (lastToken === 'affinity') {
+          return completeSubcommands(['on', 'off', '--ttl']);
+        }
+        return completeSubcommands(['set', 'explain', 'affinity']);
       }
       if (['remove', 'edit'].includes(subcommand)) {
         return completeSubcommands(getProfileNames('cliproxyVariants'), ['--yes', '-y']);
diff --git a/src/config/unified-config-loader.ts b/src/config/unified-config-loader.ts
index 261b2d72..12e348c8 100644
--- a/src/config/unified-config-loader.ts
+++ b/src/config/unified-config-loader.ts
@@ -440,6 +440,15 @@ function mergeWithDefaults(partial: Partial<UnifiedConfig>): UnifiedConfig {
           partial.cliproxy?.routing?.strategy === 'round-robin'
             ? partial.cliproxy.routing.strategy
             : defaults.cliproxy.routing?.strategy,
+        session_affinity:
+          typeof partial.cliproxy?.routing?.session_affinity === 'boolean'
+            ? partial.cliproxy.routing.session_affinity
+            : defaults.cliproxy.routing?.session_affinity,
+        session_affinity_ttl:
+          typeof partial.cliproxy?.routing?.session_affinity_ttl === 'string' &&
+          partial.cliproxy.routing.session_affinity_ttl.trim()
+            ? partial.cliproxy.routing.session_affinity_ttl.trim()
+            : defaults.cliproxy.routing?.session_affinity_ttl,
       },
     },
     proxy: {
diff --git a/src/config/unified-config-types.ts b/src/config/unified-config-types.ts
index 4639744c..ab4eca6c 100644
--- a/src/config/unified-config-types.ts
+++ b/src/config/unified-config-types.ts
@@ -205,6 +205,10 @@ export interface TokenRefreshSettings {
 export interface CLIProxyRoutingConfig {
   /** Credential selection strategy when multiple accounts match */
   strategy?: CliproxyRoutingStrategy;
+  /** Keep one conversation pinned to the same account when possible */
+  session_affinity?: boolean;
+  /** Go-style duration for session-affinity binding retention */
+  session_affinity_ttl?: string;
 }
 
 /**
@@ -1034,6 +1038,8 @@ export function createEmptyUnifiedConfig(): UnifiedConfig {
       auto_sync: true,
       routing: {
         strategy: 'round-robin',
+        session_affinity: false,
+        session_affinity_ttl: '1h',
       },
     },
     proxy: {
diff --git a/src/web-server/routes/cliproxy-routing-routes.ts b/src/web-server/routes/cliproxy-routing-routes.ts
index d1a21b54..93c63ac4 100644
--- a/src/web-server/routes/cliproxy-routing-routes.ts
+++ b/src/web-server/routes/cliproxy-routing-routes.ts
@@ -1,8 +1,12 @@
 import { Router, Request, Response } from 'express';
 import {
   applyCliproxyRoutingStrategy,
+  applyCliproxySessionAffinitySettings,
   normalizeCliproxyRoutingStrategy,
+  normalizeCliproxySessionAffinityEnabled,
+  normalizeCliproxySessionAffinityTtl,
   readCliproxyRoutingState,
+  readCliproxySessionAffinityState,
 } from '../../cliproxy/routing-strategy';
 import { requireLocalAccessWhenAuthDisabled } from '../middleware/auth-middleware';
 
@@ -42,4 +46,37 @@ router.put('/routing/strategy', async (req: Request, res: Response): Promise<voi
   }
 });
 
+router.get('/routing/session-affinity', async (_req: Request, res: Response): Promise<void> => {
+  try {
+    res.json(await readCliproxySessionAffinityState());
+  } catch (error) {
+    res.status(502).json({ error: (error as Error).message });
+  }
+});
+
+router.put('/routing/session-affinity', async (req: Request, res: Response): Promise<void> => {
+  const enabled = normalizeCliproxySessionAffinityEnabled(req.body?.enabled ?? req.body?.value);
+  const ttl = req.body?.ttl;
+  const normalizedTtl: string | undefined =
+    ttl === undefined ? undefined : (normalizeCliproxySessionAffinityTtl(ttl) ?? undefined);
+
+  if (enabled === null || (ttl !== undefined && !normalizedTtl)) {
+    res.status(400).json({
+      error: 'Invalid session affinity payload. Use enabled=true|false and ttl like 30m or 1h.',
+    });
+    return;
+  }
+
+  try {
+    res.json(
+      await applyCliproxySessionAffinitySettings({
+        enabled,
+        ttl: normalizedTtl,
+      })
+    );
+  } catch (error) {
+    res.status(502).json({ error: (error as Error).message });
+  }
+});
+
 export default router;
diff --git a/tests/unit/cliproxy/routing-strategy.test.ts b/tests/unit/cliproxy/routing-strategy.test.ts
index 3a195e14..9d222d7e 100644
--- a/tests/unit/cliproxy/routing-strategy.test.ts
+++ b/tests/unit/cliproxy/routing-strategy.test.ts
@@ -151,4 +151,111 @@ describe('cliproxy routing strategy service', () => {
       expect(methodCount).toBe(2);
     });
   });
+
+  it('normalizes session-affinity booleans and TTL values', async () => {
+    await withScopedConfig(async () => {
+      const mod = await loadRoutingModule();
+
+      expect(mod.normalizeCliproxySessionAffinityEnabled(true)).toBe(true);
+      expect(mod.normalizeCliproxySessionAffinityEnabled('on')).toBe(true);
+      expect(mod.normalizeCliproxySessionAffinityEnabled('false')).toBe(false);
+      expect(mod.normalizeCliproxySessionAffinityEnabled('maybe')).toBeNull();
+
+      expect(mod.normalizeCliproxySessionAffinityTtl('1h')).toBe('1h');
+      expect(mod.normalizeCliproxySessionAffinityTtl('2h30m')).toBe('2h30m');
+      expect(mod.normalizeCliproxySessionAffinityTtl('  15m  ')).toBe('15m');
+      expect(mod.normalizeCliproxySessionAffinityTtl('tomorrow')).toBeNull();
+    });
+  });
+
+  it('reads saved local session-affinity settings when live CLIProxy is unavailable', async () => {
+    await withScopedConfig(async () => {
+      const { mutateUnifiedConfig } = await import('../../../src/config/unified-config-loader');
+      mutateUnifiedConfig((config) => {
+        if (config.cliproxy) {
+          config.cliproxy.routing = {
+            strategy: 'round-robin',
+            session_affinity: true,
+            session_affinity_ttl: '2h30m',
+          };
+        }
+      });
+
+      const mod = await loadRoutingModule();
+      const state = await mod.readCliproxySessionAffinityState();
+
+      expect(state.enabled).toBe(true);
+      expect(state.ttl).toBe('2h30m');
+      expect(state.source).toBe('config');
+      expect(state.target).toBe('local');
+      expect(state.manageable).toBe(true);
+      expect(state.reachable).toBe(false);
+    });
+  });
+
+  it('persists local session-affinity settings even when live CLIProxy is unavailable', async () => {
+    await withScopedConfig(async () => {
+      const mod = await loadRoutingModule();
+      const result = await mod.applyCliproxySessionAffinitySettings({
+        enabled: true,
+        ttl: '2h',
+      });
+
+      expect(result.applied).toBe('config-only');
+      expect(result.enabled).toBe(true);
+      expect(result.ttl).toBe('2h');
+
+      const { loadUnifiedConfig } = await import('../../../src/config/unified-config-loader');
+      const persisted = loadUnifiedConfig();
+      expect(persisted?.cliproxy?.routing?.session_affinity).toBe(true);
+      expect(persisted?.cliproxy?.routing?.session_affinity_ttl).toBe('2h');
+    });
+  });
+
+  it('does not claim live session-affinity application just because local CLIProxy is reachable', async () => {
+    await withScopedConfig(async () => {
+      responseFactory = async () =>
+        new Response(JSON.stringify({ strategy: 'round-robin' }), {
+          status: 200,
+          headers: { 'Content-Type': 'application/json' },
+        });
+
+      const mod = await loadRoutingModule();
+      const result = await mod.applyCliproxySessionAffinitySettings({
+        enabled: true,
+        ttl: '30m',
+      });
+
+      expect(result.reachable).toBe(true);
+      expect(result.applied).toBe('config-only');
+      expect(result.message).toContain('does not verify live selector state yet');
+    });
+  });
+
+  it('reports remote session-affinity management as unsupported', async () => {
+    await withScopedConfig(async () => {
+      routingTarget = {
+        host: 'remote.example.com',
+        port: 8080,
+        protocol: 'http',
+        isRemote: true,
+      };
+
+      const mod = await loadRoutingModule();
+      const state = await mod.readCliproxySessionAffinityState();
+
+      expect(state.source).toBe('unsupported');
+      expect(state.target).toBe('remote');
+      expect(state.manageable).toBe(false);
+      expect(state.enabled).toBeUndefined();
+
+      const result = await mod.applyCliproxySessionAffinitySettings({
+        enabled: true,
+        ttl: '1h',
+      });
+
+      expect(result.applied).toBe('unsupported');
+      expect(result.manageable).toBe(false);
+    });
+  });
 });
diff --git a/tests/unit/web-server/cliproxy-routing-routes.test.ts b/tests/unit/web-server/cliproxy-routing-routes.test.ts
index ffaa71f6..a3dd9bd6 100644
--- a/tests/unit/web-server/cliproxy-routing-routes.test.ts
+++ b/tests/unit/web-server/cliproxy-routing-routes.test.ts
@@ -7,6 +7,8 @@ describe('cliproxy routing routes', () => {
   let baseUrl = '';
   let readStateMock: ReturnType<typeof mock>;
   let applyStrategyMock: ReturnType<typeof mock>;
+  let readAffinityStateMock: ReturnType<typeof mock>;
+  let applyAffinityMock: ReturnType<typeof mock>;
 
   beforeEach(async () => {
     readStateMock = mock(async () => ({
@@ -22,16 +24,43 @@ describe('cliproxy routing routes', () => {
       reachable: true,
       applied: 'live-and-config',
     }));
+    readAffinityStateMock = mock(async () => ({
+      enabled: true,
+      ttl: '1h',
+      source: 'config',
+      target: 'local',
+      reachable: true,
+      manageable: true,
+    }));
+    applyAffinityMock = mock(async () => ({
+      enabled: false,
+      ttl: '30m',
+      source: 'config',
+      target: 'local',
+      reachable: true,
+      manageable: true,
+      applied: 'config-only',
+    }));
 
     mock.module('../../../src/cliproxy/routing-strategy', () => ({
       readCliproxyRoutingState: readStateMock,
       applyCliproxyRoutingStrategy: applyStrategyMock,
+      readCliproxySessionAffinityState: readAffinityStateMock,
+      applyCliproxySessionAffinitySettings: applyAffinityMock,
       normalizeCliproxyRoutingStrategy: (value: unknown) => {
         if (value === 'round-robin' || value === 'fill-first') {
           return value;
         }
         return null;
       },
+      normalizeCliproxySessionAffinityEnabled: (value: unknown) => {
+        if (value === true || value === false) return value;
+        return null;
+      },
+      normalizeCliproxySessionAffinityTtl: (value: unknown) => {
+        if (value === '30m' || value === '1h') return value;
+        return null;
+      },
     }));
 
     const { default: routingRoutes } = await import(
@@ -103,4 +132,52 @@ describe('cliproxy routing routes', () => {
       applied: 'live-and-config',
     });
   });
+
+  it('returns the current session-affinity state', async () => {
+    const response = await fetch(`${baseUrl}/api/cliproxy/routing/session-affinity`);
+    expect(response.status).toBe(200);
+    expect(await response.json()).toEqual({
+      enabled: true,
+      ttl: '1h',
+      source: 'config',
+      target: 'local',
+      reachable: true,
+      manageable: true,
+    });
+    expect(readAffinityStateMock).toHaveBeenCalledTimes(1);
+  });
+
+  it('rejects invalid session-affinity payloads', async () => {
+    const response = await fetch(`${baseUrl}/api/cliproxy/routing/session-affinity`, {
+      method: 'PUT',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({ enabled: 'auto', ttl: 'forever' }),
+    });
+
+    expect(response.status).toBe(400);
+    expect(await response.json()).toEqual({
+      error: 'Invalid session affinity payload. Use enabled=true|false and ttl like 30m or 1h.',
+    });
+    expect(applyAffinityMock).not.toHaveBeenCalled();
+  });
+
+  it('applies valid session-affinity settings', async () => {
+    const response = await fetch(`${baseUrl}/api/cliproxy/routing/session-affinity`, {
+      method: 'PUT',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({ enabled: false, ttl: '30m' }),
+    });
+
+    expect(response.status).toBe(200);
+    expect(applyAffinityMock).toHaveBeenCalledWith({ enabled: false, ttl: '30m' });
+    expect(await response.json()).toEqual({
+      enabled: false,
+      ttl: '30m',
+      source: 'config',
+      target: 'local',
+      reachable: true,
+      manageable: true,
+      applied: 'config-only',
+    });
+  });
 });
diff --git a/ui/src/components/cliproxy/routing-guidance-card.tsx b/ui/src/components/cliproxy/routing-guidance-card.tsx
index bffc9230..94cbe112 100644
--- a/ui/src/components/cliproxy/routing-guidance-card.tsx
+++ b/ui/src/components/cliproxy/routing-guidance-card.tsx
@@ -1,8 +1,12 @@
-import { useState } from 'react';
+import { useEffect, useRef, useState } from 'react';
 import { ArrowRightLeft, ChevronDown, ChevronUp, RefreshCw } from 'lucide-react';
 import { Badge } from '@/components/ui/badge';
 import { Button } from '@/components/ui/button';
-import type { CliproxyRoutingState, RoutingStrategy } from '@/lib/api-client';
+import type {
+  CliproxyRoutingState,
+  RoutingStrategy,
+  CliproxySessionAffinityState,
+} from '@/lib/api-client';
 import { cn } from '@/lib/utils';
 import { useTranslation } from 'react-i18next';
 
@@ -10,10 +14,12 @@ interface RoutingGuidanceCardProps {
   className?: string;
   compact?: boolean;
   state?: CliproxyRoutingState;
+  sessionAffinityState?: CliproxySessionAffinityState;
   isLoading: boolean;
   isSaving: boolean;
   error?: Error | null;
   onApply: (strategy: RoutingStrategy) => void;
+  onApplyAffinity: (data: { enabled: boolean; ttl?: string }) => void;
 }
 
 const STRATEGY_COPY: Record<RoutingStrategy, { title: string; description: string }> = {
@@ -31,18 +37,77 @@ export function RoutingGuidanceCard({
   className,
   compact = false,
   state,
+  sessionAffinityState,
   isLoading,
   isSaving,
   error,
   onApply,
+  onApplyAffinity,
 }: RoutingGuidanceCardProps) {
   const { t } = useTranslation();
   const currentStrategy = state?.strategy ?? 'round-robin';
+  const currentAffinityEnabled = sessionAffinityState?.enabled ?? false;
+  const currentAffinityTtl = sessionAffinityState?.ttl ?? '1h';
+  const sessionAffinityManageable = sessionAffinityState?.manageable ?? true;
   const [selected, setSelected] = useState<RoutingStrategy>(currentStrategy);
+  const [selectedAffinityEnabled, setSelectedAffinityEnabled] = useState(currentAffinityEnabled);
+  const [selectedAffinityTtl, setSelectedAffinityTtl] = useState(currentAffinityTtl);
   const [detailsOpen, setDetailsOpen] = useState(false);
   const sourceLabel = state?.source === 'live' ? 'Live CLIProxy' : 'Saved startup default';
   const saveDisabled = isLoading || isSaving || !state || selected === currentStrategy;
   const detailToggleLabel = detailsOpen ? 'Hide details' : 'Show details';
+  const affinityControlDisabled = isLoading || isSaving || !!error || !sessionAffinityManageable;
+  const affinityActionLabel = sessionAffinityManageable
+    ? selectedAffinityEnabled
+      ? 'Disable session affinity'
+      : 'Enable session affinity'
+    : 'Session affinity unavailable';
+  const pendingAffinityRef = useRef<{ enabled: boolean; ttl: string } | null>(null);
+
+  useEffect(() => {
+    setSelected(currentStrategy);
+  }, [currentStrategy]);
+
+  useEffect(() => {
+    setSelectedAffinityEnabled(currentAffinityEnabled);
+    setSelectedAffinityTtl(currentAffinityTtl);
+  }, [currentAffinityEnabled, currentAffinityTtl]);
+
+  useEffect(() => {
+    if (isSaving || !pendingAffinityRef.current) {
+      return;
+    }
+
+    const pending = pendingAffinityRef.current;
+    const succeeded =
+      pending.enabled === currentAffinityEnabled && pending.ttl === currentAffinityTtl;
+
+    if (!succeeded) {
+      setSelectedAffinityEnabled(currentAffinityEnabled);
+      setSelectedAffinityTtl(currentAffinityTtl);
+    }
+
+    pendingAffinityRef.current = null;
+  }, [isSaving, currentAffinityEnabled, currentAffinityTtl]);
+
+  const handleAffinityToggle = () => {
+    if (!sessionAffinityManageable) return;
+    const nextEnabled = !selectedAffinityEnabled;
+    const nextTtl = selectedAffinityTtl.trim() || '1h';
+    pendingAffinityRef.current = { enabled: nextEnabled, ttl: nextTtl };
+    setSelectedAffinityEnabled(nextEnabled);
+    onApplyAffinity({ enabled: nextEnabled, ttl: nextTtl });
+  };
+
+  const handleAffinityTtlBlur = () => {
+    if (!sessionAffinityManageable || !!error) return;
+    const nextTtl = selectedAffinityTtl.trim() || '1h';
+    if (nextTtl === currentAffinityTtl) {
+      return;
+    }
+    pendingAffinityRef.current = { enabled: selectedAffinityEnabled, ttl: nextTtl };
+    onApplyAffinity({ enabled: selectedAffinityEnabled, ttl: nextTtl });
+  };
 
   if (compact) {
     const handleApply = (s: RoutingStrategy) => {
@@ -53,57 +118,96 @@ export function RoutingGuidanceCard({
     };
 
     return (
-      <div
-        className={cn(
-          'group/routing flex items-center justify-between mt-1 p-1 -mx-1 rounded-lg transition-colors hover:bg-primary/5',
-          className
-        )}
-      >
-        <div className="flex items-center gap-2 text-xs font-medium text-foreground">
-          <div className="relative flex h-6 w-6 shrink-0 items-center justify-center rounded-md bg-background border border-border/60 text-muted-foreground shadow-sm overflow-hidden transition-all duration-300 group-hover/routing:border-primary/40 group-hover/routing:text-primary group-hover/routing:shadow-[0_0_12px_rgba(59,130,246,0.15)] dark:group-hover/routing:shadow-[0_0_12px_rgba(59,130,246,0.1)]">
-            <div className="absolute inset-0 bg-primary/10 translate-y-full group-hover/routing:translate-y-0 transition-transform duration-300 ease-out" />
-            <ArrowRightLeft className="relative z-10 h-3.5 w-3.5 transition-transform duration-300 group-hover/routing:scale-110" />
+      <div className={cn('group/routing mt-1 space-y-2 -mx-1 rounded-lg p-1', className)}>
+        <div className="flex items-center justify-between rounded-lg transition-colors hover:bg-primary/5">
+          <div className="flex items-center gap-2 px-1 text-xs font-medium text-foreground">
+            <div className="relative flex h-6 w-6 shrink-0 items-center justify-center rounded-md bg-background border border-border/60 text-muted-foreground shadow-sm overflow-hidden transition-all duration-300 group-hover/routing:border-primary/40 group-hover/routing:text-primary group-hover/routing:shadow-[0_0_12px_rgba(59,130,246,0.15)] dark:group-hover/routing:shadow-[0_0_12px_rgba(59,130,246,0.1)]">
+              <div className="absolute inset-0 bg-primary/10 translate-y-full group-hover/routing:translate-y-0 transition-transform duration-300 ease-out" />
+              <ArrowRightLeft className="relative z-10 h-3.5 w-3.5 transition-transform duration-300 group-hover/routing:scale-110" />
+            </div>
+            <span className="tracking-tight transition-colors duration-300 group-hover/routing:text-primary group-hover/routing:font-semibold">
+              Routing
+            </span>
+            {isSaving && <RefreshCw className="ml-1 h-3 w-3 shrink-0 animate-spin text-primary" />}
+          </div>
+
+          <div className="relative grid grid-cols-2 p-0.5 gap-0.5 rounded-lg border border-border/60 bg-muted/30 shadow-[inset_0_1px_2px_rgba(0,0,0,0.05)] dark:shadow-[inset_0_1px_3px_rgba(0,0,0,0.2)] transition-colors duration-300 group-hover/routing:border-primary/20 group-hover/routing:bg-primary/5">
+            <div
+              className={cn(
+                'absolute inset-y-0.5 left-0.5 w-[calc(50%-0.1875rem)] rounded bg-background shadow-[0_1px_3px_rgba(0,0,0,0.1),0_1px_2px_rgba(0,0,0,0.06)] ring-1 ring-black/5 dark:ring-white/10 transition-all duration-300',
+                selected === 'fill-first' ? 'translate-x-[calc(100%+0.125rem)]' : 'translate-x-0',
+                'group-hover/routing:shadow-[0_0_8px_rgba(59,130,246,0.15)] dark:group-hover/routing:shadow-[0_0_8px_rgba(59,130,246,0.1)] group-hover/routing:ring-primary/30'
+              )}
+              style={{ transitionTimingFunction: 'cubic-bezier(0.175, 0.885, 0.32, 1.275)' }}
+            />
+            {(
+              Object.entries(STRATEGY_COPY) as Array<
+                [RoutingStrategy, { title: string; description: string }]
+              >
+            ).map(([strategy, copy]) => {
+              const active = selected === strategy;
+              return (
+                <button
+                  key={strategy}
+                  type="button"
+                  className={cn(
+                    'relative z-10 flex items-center justify-center rounded px-2.5 py-0.5 text-[10px] font-medium whitespace-nowrap transition-colors duration-200',
+                    active
+                      ? 'text-foreground group-hover/routing:text-primary'
+                      : 'text-muted-foreground/70 hover:text-foreground/90 group-hover/routing:text-muted-foreground/90'
+                  )}
+                  onClick={() => handleApply(strategy)}
+                  disabled={isLoading || isSaving || !!error}
+                  title={copy.description}
+                >
+                  {copy.title}
+                </button>
+              );
+            })}
           </div>
-          <span className="tracking-tight transition-colors duration-300 group-hover/routing:text-primary group-hover/routing:font-semibold">
-            Routing
-          </span>
-          {isSaving && <RefreshCw className="ml-1 h-3 w-3 shrink-0 animate-spin text-primary" />}
         </div>
 
-        <div className="relative grid grid-cols-2 p-0.5 gap-0.5 rounded-lg border border-border/60 bg-muted/30 shadow-[inset_0_1px_2px_rgba(0,0,0,0.05)] dark:shadow-[inset_0_1px_3px_rgba(0,0,0,0.2)] transition-colors duration-300 group-hover/routing:border-primary/20 group-hover/routing:bg-primary/5">
-          <div
-            className={cn(
-              'absolute inset-y-0.5 left-0.5 w-[calc(50%-0.1875rem)] rounded bg-background shadow-[0_1px_3px_rgba(0,0,0,0.1),0_1px_2px_rgba(0,0,0,0.06)] ring-1 ring-black/5 dark:ring-white/10 transition-all duration-300',
-              selected === 'fill-first' ? 'translate-x-[calc(100%+0.125rem)]' : 'translate-x-0',
-              'group-hover/routing:shadow-[0_0_8px_rgba(59,130,246,0.15)] dark:group-hover/routing:shadow-[0_0_8px_rgba(59,130,246,0.1)] group-hover/routing:ring-primary/30'
-            )}
-            style={{ transitionTimingFunction: 'cubic-bezier(0.175, 0.885, 0.32, 1.275)' }}
-          />
-          {(
-            Object.entries(STRATEGY_COPY) as Array<
-              [RoutingStrategy, { title: string; description: string }]
+        <div className="flex items-center justify-between gap-2 rounded-lg border border-border/60 bg-muted/20 px-2 py-1.5">
+          <div className="min-w-0">
+            <div className="text-[10px] font-medium text-foreground">Session affinity</div>
+            <div className="text-[10px] text-muted-foreground">
+              {sessionAffinityManageable ? `TTL ${currentAffinityTtl}` : 'Local-only setting'}
+            </div>
+          </div>
+          <div className="flex items-center gap-1">
+            {sessionAffinityManageable ? (
+              <input
+                aria-label="Session affinity TTL"
+                className="h-6 w-14 rounded border border-border/70 bg-background px-2 text-[10px] text-foreground"
+                value={selectedAffinityTtl}
+                onChange={(event) => setSelectedAffinityTtl(event.target.value)}
+                onBlur={handleAffinityTtlBlur}
+                disabled={affinityControlDisabled}
+              />
+            ) : null}
+            <button
+              type="button"
+              aria-label={affinityActionLabel}
+              className={cn(
+                'rounded border px-2 py-1 text-[10px] font-medium transition-colors',
+                sessionAffinityManageable
+                  ? 'border-border/70 bg-background text-foreground hover:border-primary/40 hover:text-primary'
+                  : 'border-border/60 bg-muted/40 text-muted-foreground'
+              )}
+              onClick={handleAffinityToggle}
+              disabled={affinityControlDisabled}
+              title={sessionAffinityState?.message}
             >
-          ).map(([strategy, copy]) => {
-            const active = selected === strategy;
-            return (
-              <button
-                key={strategy}
-                type="button"
-                className={cn(
-                  'relative z-10 flex items-center justify-center rounded px-2.5 py-0.5 text-[10px] font-medium whitespace-nowrap transition-colors duration-200',
-                  active
-                    ? 'text-foreground group-hover/routing:text-primary'
-                    : 'text-muted-foreground/70 hover:text-foreground/90 group-hover/routing:text-muted-foreground/90'
-                )}
-                onClick={() => handleApply(strategy)}
-                disabled={isLoading || isSaving || !!error}
-                title={copy.description}
-              >
-                {copy.title}
-              </button>
-            );
-          })}
+              {sessionAffinityManageable ? (selectedAffinityEnabled ? 'On' : 'Off') : 'Unavailable'}
+            </button>
+          </div>
         </div>
+
+        {sessionAffinityState?.message ? (
+          <div className="rounded-lg border border-border/60 bg-muted/20 px-2 py-1.5 text-[10px] text-muted-foreground">
+            {sessionAffinityState.message}
+          </div>
+        ) : null}
       </div>
     );
   }
@@ -181,6 +285,50 @@ export function RoutingGuidanceCard({
           <span>{t('routingGuidance.fillFirst')}</span>
         </div>
 
+        <div className="grid gap-3 rounded-lg border border-border/70 bg-muted/20 px-3 py-3 xl:col-span-2">
+          <div className="flex flex-wrap items-center gap-2">
+            <div className="text-sm font-medium">Session affinity</div>
+            <Badge variant="secondary">{selectedAffinityEnabled ? 'on' : 'off'}</Badge>
+            {sessionAffinityState?.ttl ? (
+              <Badge variant="outline">TTL {currentAffinityTtl}</Badge>
+            ) : null}
+            {!sessionAffinityManageable ? <Badge variant="outline">Local only</Badge> : null}
+          </div>
+          <p className="text-xs leading-5 text-muted-foreground">
+            Keep one conversation pinned to the same account when possible. CLIProxy prefers
+            explicit session or thread identifiers when clients send them, then falls back to
+            request metadata or the opening prompt history when it has to infer a stable key.
+          </p>
+          <div className="flex flex-wrap items-center gap-2">
+            <input
+              aria-label="Session affinity TTL"
+              className="h-9 w-24 rounded-md border border-border/70 bg-background px-3 text-sm text-foreground"
+              value={selectedAffinityTtl}
+              onChange={(event) => setSelectedAffinityTtl(event.target.value)}
+              onBlur={handleAffinityTtlBlur}
+              disabled={affinityControlDisabled}
+            />
+            <Button
+              type="button"
+              variant="outline"
+              onClick={handleAffinityToggle}
+              disabled={affinityControlDisabled}
+              aria-label={affinityActionLabel}
+            >
+              {sessionAffinityManageable
+                ? selectedAffinityEnabled
+                  ? 'Disable session affinity'
+                  : 'Enable session affinity'
+                : 'Session affinity unavailable'}
+            </Button>
+          </div>
+          {sessionAffinityState?.message ? (
+            <div className="rounded-lg border border-border/70 bg-background/70 px-3 py-2 text-xs text-muted-foreground">
+              {sessionAffinityState.message}
+            </div>
+          ) : null}
+        </div>
+
         {error ? (
           <div className="rounded-lg border border-destructive/25 bg-destructive/5 px-3 py-2 text-sm xl:col-span-2">
             {error.message}
@@ -210,6 +358,14 @@ export function RoutingGuidanceCard({
                 </div>
               );
             })}
+            <div className="space-y-1 md:col-span-2">
+              <div className="text-sm font-medium">Session recognition order</div>
+              <p className="text-xs leading-5 text-muted-foreground">
+                CCS does not promise one universal precedence order here. In practice, upstream
+                backends prefer explicit session or thread ids first, then fall back to metadata
+                fields and finally a hash based on the opening prompt history.
+              </p>
+            </div>
           </div>
         ) : null}
       </div>
diff --git a/ui/src/components/monitoring/proxy-status-widget.tsx b/ui/src/components/monitoring/proxy-status-widget.tsx
index 484569fc..3ad7809b 100644
--- a/ui/src/components/monitoring/proxy-status-widget.tsx
+++ b/ui/src/components/monitoring/proxy-status-widget.tsx
@@ -61,7 +61,9 @@ import {
   useInstallVersion,
   useRestartProxy,
   useCliproxyRoutingStrategy,
+  useCliproxySessionAffinity,
   useUpdateCliproxyRoutingStrategy,
+  useUpdateCliproxySessionAffinity,
 } from '@/hooks/use-cliproxy';
 import { useSyncStatus, useExecuteSync } from '@/hooks/use-cliproxy-sync';
 import { cn } from '@/lib/utils';
@@ -159,6 +161,19 @@ export function ProxyStatusWidget() {
     error: routingError,
   } = useCliproxyRoutingStrategy();
   const updateRouting = useUpdateCliproxyRoutingStrategy();
+  const {
+    data: sessionAffinityState,
+    isLoading: sessionAffinityLoading,
+    error: sessionAffinityError,
+  } = useCliproxySessionAffinity();
+  const updateSessionAffinity = useUpdateCliproxySessionAffinity();
+  const isSavingRoutingConfig = updateRouting.isPending || updateSessionAffinity.isPending;
+  const routingConfigError =
+    routingError instanceof Error
+      ? routingError
+      : sessionAffinityError instanceof Error
+        ? sessionAffinityError
+        : null;
   const startProxy = useStartProxy();
   const stopProxy = useStopProxy();
   const restartProxy = useRestartProxy();
@@ -315,14 +330,16 @@ export function ProxyStatusWidget() {
         </div>
 
         <RoutingGuidanceCard
-          key={`remote:${routingState?.strategy ?? 'round-robin'}`}
+          key={`remote:${routingState?.strategy ?? 'round-robin'}:${sessionAffinityState?.enabled ?? 'na'}:${sessionAffinityState?.ttl ?? 'na'}:${sessionAffinityState?.manageable ?? 'na'}`}
           compact
           className="mt-3"
           state={routingState}
-          isLoading={routingLoading}
-          isSaving={updateRouting.isPending}
-          error={routingError instanceof Error ? routingError : null}
+          sessionAffinityState={sessionAffinityState}
+          isLoading={routingLoading || sessionAffinityLoading}
+          isSaving={isSavingRoutingConfig}
+          error={routingConfigError}
           onApply={(strategy) => updateRouting.mutate(strategy)}
+          onApplyAffinity={(data) => updateSessionAffinity.mutate(data)}
         />
       </div>
     );
@@ -471,14 +488,16 @@ export function ProxyStatusWidget() {
         </div>
 
         <RoutingGuidanceCard
-          key={`local:${routingState?.strategy ?? 'round-robin'}`}
+          key={`local:${routingState?.strategy ?? 'round-robin'}:${sessionAffinityState?.enabled ?? 'na'}:${sessionAffinityState?.ttl ?? 'na'}:${sessionAffinityState?.manageable ?? 'na'}`}
           compact
           className="mt-3"
           state={routingState}
-          isLoading={routingLoading}
-          isSaving={updateRouting.isPending}
-          error={routingError instanceof Error ? routingError : null}
+          sessionAffinityState={sessionAffinityState}
+          isLoading={routingLoading || sessionAffinityLoading}
+          isSaving={isSavingRoutingConfig}
+          error={routingConfigError}
           onApply={(strategy) => updateRouting.mutate(strategy)}
+          onApplyAffinity={(data) => updateSessionAffinity.mutate(data)}
         />
 
         {/* Expanded section: Version Management (available even when not running) */}
diff --git a/ui/src/hooks/use-cliproxy.ts b/ui/src/hooks/use-cliproxy.ts
index ff1e9354..c7a58dd0 100644
--- a/ui/src/hooks/use-cliproxy.ts
+++ b/ui/src/hooks/use-cliproxy.ts
@@ -11,6 +11,7 @@ import {
   type UpdateVariant,
   type CreatePreset,
   type RoutingStrategy,
+  type CliproxySessionAffinityApplyResult,
 } from '@/lib/api-client';
 import { toast } from 'sonner';
 import { useTranslation } from 'react-i18next';
@@ -18,6 +19,7 @@ import { useTranslation } from 'react-i18next';
 function invalidateCliproxyRoutingQueries(queryClient: ReturnType<typeof useQueryClient>): void {
   queryClient.invalidateQueries({ queryKey: ['cliproxy-catalog'] });
   queryClient.invalidateQueries({ queryKey: ['cliproxy-models'] });
+  queryClient.invalidateQueries({ queryKey: ['cliproxy-session-affinity'] });
 }
 
 function invalidateCliproxyAccountQueries(queryClient: ReturnType<typeof useQueryClient>): void {
@@ -74,6 +76,30 @@ export function useUpdateCliproxyRoutingStrategy() {
   });
 }
 
+export function useCliproxySessionAffinity() {
+  return useQuery({
+    queryKey: ['cliproxy-session-affinity'],
+    queryFn: () => api.cliproxy.getSessionAffinity(),
+  });
+}
+
+export function useUpdateCliproxySessionAffinity() {
+  const queryClient = useQueryClient();
+
+  return useMutation({
+    mutationFn: (data: { enabled: boolean; ttl?: string }) =>
+      api.cliproxy.updateSessionAffinity(data),
+    onSuccess: (result: CliproxySessionAffinityApplyResult) => {
+      queryClient.invalidateQueries({ queryKey: ['cliproxy-session-affinity'] });
+      const label = result.enabled ? 'enabled' : 'disabled';
+      toast.success(result.message || `Session affinity ${label}.`);
+    },
+    onError: (error: Error) => {
+      toast.error(error.message);
+    },
+  });
+}
+
 export function useCreateVariant() {
   const queryClient = useQueryClient();
   const { t } = useTranslation();
diff --git a/ui/src/lib/api-client.ts b/ui/src/lib/api-client.ts
index e48e4dc4..566ce094 100644
--- a/ui/src/lib/api-client.ts
+++ b/ui/src/lib/api-client.ts
@@ -521,6 +521,20 @@ export interface CliproxyRoutingApplyResult extends CliproxyRoutingState {
   applied: 'live' | 'live-and-config' | 'config-only';
 }
 
+export interface CliproxySessionAffinityState {
+  enabled?: boolean;
+  ttl?: string;
+  source: 'config' | 'unsupported';
+  target: 'local' | 'remote';
+  reachable: boolean;
+  manageable: boolean;
+  message?: string;
+}
+
+export interface CliproxySessionAffinityApplyResult extends CliproxySessionAffinityState {
+  applied: 'config-and-live' | 'config-only' | 'unsupported';
+}
+
 /** Auth file info for Config tab */
 export interface AuthFile {
   name: string;
@@ -1253,6 +1267,13 @@ export const api = {
         method: 'PUT',
         body: JSON.stringify({ value: strategy }),
       }),
+    getSessionAffinity: () =>
+      request<CliproxySessionAffinityState>('/cliproxy/routing/session-affinity'),
+    updateSessionAffinity: (data: { enabled: boolean; ttl?: string }) =>
+      request<CliproxySessionAffinityApplyResult>('/cliproxy/routing/session-affinity', {
+        method: 'PUT',
+        body: JSON.stringify(data),
+      }),
     aiProviders: {
       list: () => request<ListAiProvidersResult>('/cliproxy/ai-providers'),
       create: (family: AiProviderFamilyId, data: UpsertAiProviderEntryInput) =>
diff --git a/ui/tests/unit/components/cliproxy/routing-guidance-card.test.tsx b/ui/tests/unit/components/cliproxy/routing-guidance-card.test.tsx
index f22a8aae..6fc4e1f3 100644
--- a/ui/tests/unit/components/cliproxy/routing-guidance-card.test.tsx
+++ b/ui/tests/unit/components/cliproxy/routing-guidance-card.test.tsx
@@ -5,6 +5,7 @@ import { RoutingGuidanceCard } from '@/components/cliproxy/routing-guidance-card
 describe('RoutingGuidanceCard', () => {
   it('shows the current strategy and applies an explicit change', async () => {
     const onApply = vi.fn();
+    const onApplyAffinity = vi.fn();
 
     render(
       <RoutingGuidanceCard
@@ -14,19 +15,33 @@ describe('RoutingGuidanceCard', () => {
           target: 'local',
           reachable: true,
         }}
+        sessionAffinityState={{
+          enabled: true,
+          ttl: '1h',
+          source: 'config',
+          target: 'local',
+          reachable: true,
+          manageable: true,
+        }}
         isLoading={false}
         isSaving={false}
         onApply={onApply}
+        onApplyAffinity={onApplyAffinity}
       />
     );
 
     expect(screen.getByText('Routing strategy')).toBeInTheDocument();
     expect(screen.getAllByText('round-robin').length).toBeGreaterThan(0);
+    expect(screen.getByText('Session affinity')).toBeInTheDocument();
+    expect(screen.getByDisplayValue('1h')).toBeInTheDocument();
 
     fireEvent.click(screen.getByRole('button', { name: /fill first/i }));
     fireEvent.click(screen.getByRole('button', { name: /use fill-first/i }));
 
     expect(onApply).toHaveBeenCalledWith('fill-first');
+
+    fireEvent.click(screen.getByRole('button', { name: /disable session affinity/i }));
+    expect(onApplyAffinity).toHaveBeenCalledWith({ enabled: false, ttl: '1h' });
   });
 
   it('shows the error state and disables apply', () => {
@@ -36,10 +51,40 @@ describe('RoutingGuidanceCard', () => {
         isSaving={false}
         error={new Error('Remote CLIProxy is not reachable')}
         onApply={() => undefined}
+        onApplyAffinity={() => undefined}
       />
     );
 
     expect(screen.getByText('Remote CLIProxy is not reachable')).toBeInTheDocument();
     expect(screen.getByRole('button', { name: /use round-robin/i })).toBeDisabled();
   });
+
+  it('shows remote session-affinity guidance when the setting is not manageable', () => {
+    render(
+      <RoutingGuidanceCard
+        state={{
+          strategy: 'round-robin',
+          source: 'live',
+          target: 'remote',
+          reachable: true,
+        }}
+        sessionAffinityState={{
+          source: 'unsupported',
+          target: 'remote',
+          reachable: true,
+          manageable: false,
+          message: 'Remote session-affinity management is not supported from CCS yet.',
+        }}
+        isLoading={false}
+        isSaving={false}
+        onApply={() => undefined}
+        onApplyAffinity={() => undefined}
+      />
+    );
+
+    expect(
+      screen.getByText('Remote session-affinity management is not supported from CCS yet.')
+    ).toBeInTheDocument();
+    expect(screen.getByRole('button', { name: /session affinity unavailable/i })).toBeDisabled();
+  });
 });