diff --git a/packages/coding-agent/CHANGELOG.md b/packages/coding-agent/CHANGELOG.md
index 8846e99e6..882d38356 100644
--- a/packages/coding-agent/CHANGELOG.md
+++ b/packages/coding-agent/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- Fixed Hindsight retain/recall/reflect calls staying pinned to the bank that was selected when the session started after the operator edited `hindsight.bankId`, `hindsight.bankIdPrefix`, or `hindsight.scoping` mid-session. The backend now subscribes to those settings via `onHindsightScopeChanged` and rebuilds the active `HindsightSessionState` against the recomputed scope, disposing the old state after flushing its queue so in-flight tool-initiated retains still land in the bank they were enqueued for. Also renamed `ensureBankMission` to `ensureBankExists` so a blank `bankMission` no longer skips bank creation entirely, and called it before mental-model bootstrap so `createMentalModel` is never the first POST against a missing bank. `AgentSession.dispose` now flushes the retain queue before clearing `#hindsightSessionState`, since the queue's identity guard would otherwise drop the spliced batch ([#1902](https://github.com/can1357/oh-my-pi/issues/1902)).
+
 ## [15.9.1] - 2026-06-04
 
 ### Added
diff --git a/packages/coding-agent/src/config/settings.ts b/packages/coding-agent/src/config/settings.ts
index c735aa770..f5dc33299 100644
--- a/packages/coding-agent/src/config/settings.ts
+++ b/packages/coding-agent/src/config/settings.ts
@@ -907,6 +907,9 @@ const SETTING_HOOKS: Partial<Record<SettingPath, SettingHook<any>>> = {
 			for (const cb of appendOnlyModeCallbacks) cb(value);
 		}
 	},
+	"hindsight.bankId": () => fireHindsightScopeChanged(),
+	"hindsight.bankIdPrefix": () => fireHindsightScopeChanged(),
+	"hindsight.scoping": () => fireHindsightScopeChanged(),
 };
 /** Callbacks invoked when `provider.appendOnlyContext` changes at runtime. */
 const appendOnlyModeCallbacks = new Set<(value: string) => void>();
@@ -923,6 +926,41 @@ export function onAppendOnlyModeChanged(cb: (value: string) => void): () => void
 	};
 }
 
+/** Callbacks fired when any `hindsight.bankId` / `bankIdPrefix` / `scoping` value changes. */
+const hindsightScopeCallbacks = new Set<() => void>();
+
+function fireHindsightScopeChanged(): void {
+	// Snapshot the callback set before invoking — a callback's body is allowed
+	// to subscribe a NEW callback (the Hindsight backend re-registers the
+	// fresh state's listener on every rebuild). Iterating the live Set would
+	// re-invoke those just-added callbacks within the same fire, which spins
+	// in place: subscribe → invoke → subscribe → invoke → …
+	for (const cb of [...hindsightScopeCallbacks]) {
+		try {
+			cb();
+		} catch (err) {
+			logger.warn("Settings: hindsight scope hook failed", { error: String(err) });
+		}
+	}
+}
+
+/**
+ * Subscribe to changes in the Hindsight bank-scoping settings. Lets the
+ * Hindsight backend rebuild the active `HindsightSessionState` when the
+ * operator switches `hindsight.bankId`, `hindsight.bankIdPrefix`, or
+ * `hindsight.scoping` mid-session so subsequent retain/recall calls land in
+ * the new bank instead of the one selected at session start.
+ *
+ * Returns an unsubscribe function. The callback receives no arguments — the
+ * caller is expected to re-read the relevant settings via `Settings.get`.
+ */
+export function onHindsightScopeChanged(cb: () => void): () => void {
+	hindsightScopeCallbacks.add(cb);
+	return () => {
+		hindsightScopeCallbacks.delete(cb);
+	};
+}
+
 // ═══════════════════════════════════════════════════════════════════════════
 // Global Singleton
 // ═══════════════════════════════════════════════════════════════════════════
diff --git a/packages/coding-agent/src/hindsight/backend.ts b/packages/coding-agent/src/hindsight/backend.ts
index 2d00dee27..79ff8599f 100644
--- a/packages/coding-agent/src/hindsight/backend.ts
+++ b/packages/coding-agent/src/hindsight/backend.ts
@@ -9,10 +9,10 @@
 
 import type { AgentMessage } from "@oh-my-pi/pi-agent-core";
 import { logger } from "@oh-my-pi/pi-utils";
-import type { Settings } from "../config/settings";
+import { onHindsightScopeChanged, type Settings } from "../config/settings";
 import type { MemoryBackend, MemoryBackendStartOptions } from "../memory-backend/types";
 import type { AgentSession } from "../session/agent-session";
-import { computeBankScope } from "./bank";
+import { type BankScope, computeBankScope } from "./bank";
 import { createHindsightClient } from "./client";
 import { isHindsightConfigured, loadHindsightConfig } from "./config";
 import type { HindsightMessage } from "./content";
@@ -60,12 +60,16 @@ export const hindsightBackend: MemoryBackend = {
 					recallTagsMatch: parent.recallTagsMatch,
 					config: parent.config,
 					session,
-					missionsSet: parent.missionsSet,
+					banksSet: parent.banksSet,
 					lastRetainedTurn: 0,
 					hasRecalledForFirstTurn: true,
 					aliasOf: parent,
 				}),
 			);
+			// Aliases don't run auto-recall/auto-retain, so any pending retain
+			// queue belongs to the previous alias and is safe to drop after a
+			// best-effort flush (`flushRetainQueue` is no-op when empty).
+			await previous?.flushRetainQueue();
 			previous?.dispose();
 			return;
 		}
@@ -76,38 +80,7 @@ export const hindsightBackend: MemoryBackend = {
 			return;
 		}
 
-		const client = createHindsightClient(config);
-		const scope = computeBankScope(config, session.sessionManager.getCwd());
-
-		const state = new HindsightSessionState({
-			sessionId,
-			client,
-			bankId: scope.bankId,
-			retainTags: scope.retainTags,
-			recallTags: scope.recallTags,
-			recallTagsMatch: scope.recallTagsMatch,
-			config,
-			session,
-			missionsSet: new Set(),
-			lastRetainedTurn: 0,
-			hasRecalledForFirstTurn: false,
-		});
-
-		// Cleanup any stale state for this session (defensive — prevents leaks
-		// when a session is reused without going through dispose).
-		const previous = session.setHindsightSessionState(state);
-		previous?.dispose();
-		state.attachSessionListeners();
-
-		// Kick off mental-model bootstrap. Resolves asynchronously; the first
-		// turn races and is covered in `beforeAgentStartPrompt` via
-		// `mentalModelsLoadPromise`. Subsequent turns see the populated cache
-		// because `runMentalModelLoad` calls `refreshBaseSystemPrompt`.
-		if (config.mentalModelsEnabled) {
-			state.mentalModelsLoadPromise = state.runMentalModelLoad(scope).catch(err => {
-				logger.debug("Hindsight: mental-model bootstrap failed", { bankId: state.bankId, error: String(err) });
-			});
-		}
+		await installPrimaryState(session, settings, new Set());
 	},
 
 	async buildDeveloperInstructions(_agentDir, settings, session): Promise<string | undefined> {
@@ -173,6 +146,131 @@ export const hindsightBackend: MemoryBackend = {
 		return await state.recallForCompaction(flat);
 	},
 };
+/**
+ * Build (or rebuild) the primary `HindsightSessionState` for `session` from
+ * the current settings and install it. Disposes any previous primary state
+ * after flushing its retain queue so in-flight tool-initiated retains land in
+ * the bank that was selected when they were enqueued, not in the new bank.
+ *
+ * The created state takes ownership of the `onHindsightScopeChanged`
+ * subscription so subsequent `hindsight.bankId` / `bankIdPrefix` / `scoping`
+ * edits trigger another rebuild from the same wiring.
+ */
+async function installPrimaryState(
+	session: AgentSession,
+	settings: Settings,
+	banksSet: Set<string>,
+): Promise<HindsightSessionState | undefined> {
+	const sessionId = session.sessionId;
+	if (!sessionId) return undefined;
+
+	const config = loadHindsightConfig(settings);
+	if (!isHindsightConfigured(config)) return undefined;
+
+	const client = createHindsightClient(config);
+	const scope = computeBankScope(config, session.sessionManager.getCwd());
+
+	const state = new HindsightSessionState({
+		sessionId,
+		client,
+		bankId: scope.bankId,
+		retainTags: scope.retainTags,
+		recallTags: scope.recallTags,
+		recallTagsMatch: scope.recallTagsMatch,
+		config,
+		session,
+		banksSet,
+		lastRetainedTurn: 0,
+		hasRecalledForFirstTurn: false,
+	});
+
+	// Subscribe BEFORE installing: if the operator manages to flip another
+	// setting between install and subscribe, we'd miss the edge.
+	state.unsubscribeScope = onHindsightScopeChanged(() => {
+		void rebuildPrimaryStateOnScopeChange(session);
+	});
+
+	// Cleanup any stale state for this session (defensive — prevents leaks
+	// when a session is reused without going through dispose). Flush the
+	// previous state's retain queue BEFORE clearing it, otherwise
+	// `HindsightRetainQueue.#doFlush` sees `session.getHindsightSessionState()
+	// !== state` and drops the batch.
+	const previous = session.getHindsightSessionState();
+	if (previous && previous !== state) {
+		await previous.flushRetainQueue();
+	}
+	session.setHindsightSessionState(state);
+	previous?.dispose();
+	state.attachSessionListeners();
+
+	// Kick off mental-model bootstrap. Resolves asynchronously; the first
+	// turn races and is covered in `beforeAgentStartPrompt` via
+	// `mentalModelsLoadPromise`. Subsequent turns see the populated cache
+	// because `runMentalModelLoad` calls `refreshBaseSystemPrompt`.
+	if (config.mentalModelsEnabled) {
+		state.mentalModelsLoadPromise = state.runMentalModelLoad(scope).catch(err => {
+			logger.debug("Hindsight: mental-model bootstrap failed", { bankId: state.bankId, error: String(err) });
+		});
+	}
+
+	return state;
+}
+
+/**
+ * `onHindsightScopeChanged` handler: re-evaluate the bank scope from current
+ * settings and rebuild the primary state when it has actually drifted. No-op
+ * when the scope is unchanged or the session is no longer hosting a primary
+ * state (e.g. it was wiped to `undefined`, or this is a subagent alias).
+ */
+async function rebuildPrimaryStateOnScopeChange(session: AgentSession): Promise<void> {
+	const current = session.getHindsightSessionState();
+	if (!current || current.aliasOf) return;
+
+	const settings = session.settings;
+	const config = loadHindsightConfig(settings);
+	if (!isHindsightConfigured(config)) {
+		// Hindsight effectively unwired mid-session. Flush before clearing so
+		// queued retains don't get dropped by `HindsightRetainQueue.#doFlush`.
+		await current.flushRetainQueue();
+		const previous = session.setHindsightSessionState(undefined);
+		previous?.dispose();
+		return;
+	}
+
+	const next = computeBankScope(config, session.sessionManager.getCwd());
+	if (bankScopesEqual(next, current)) return;
+
+	// Preserve the banksSet so we don't re-PUT banks we've already confirmed.
+	await installPrimaryState(session, settings, current.banksSet);
+}
+
+/** Tag-array equality: order matters because we never reorder on the way in. */
+function stringArraysEqual(a: string[] | undefined, b: string[] | undefined): boolean {
+	if (a === b) return true;
+	if (!a || !b) return false;
+	if (a.length !== b.length) return false;
+	for (let i = 0; i < a.length; i++) {
+		if (a[i] !== b[i]) return false;
+	}
+	return true;
+}
+
+/**
+ * Structural compare of a freshly resolved `BankScope` against a live state's
+ * bank routing. Used by the scope-change handler to skip rebuilds that don't
+ * actually move the bank or its tag filters.
+ */
+function bankScopesEqual(
+	scope: BankScope,
+	state: Pick<HindsightSessionState, "bankId" | "retainTags" | "recallTags" | "recallTagsMatch">,
+): boolean {
+	return (
+		scope.bankId === state.bankId &&
+		stringArraysEqual(scope.retainTags, state.retainTags) &&
+		stringArraysEqual(scope.recallTags, state.recallTags) &&
+		scope.recallTagsMatch === state.recallTagsMatch
+	);
+}
 
 /** Reduce arbitrary AgentMessages into the Hindsight flat-text shape. */
 function flattenMessagesForRecall(messages: AgentMessage[]): HindsightMessage[] {
diff --git a/packages/coding-agent/src/hindsight/bank.ts b/packages/coding-agent/src/hindsight/bank.ts
index a6f9cc149..32bc28ce4 100644
--- a/packages/coding-agent/src/hindsight/bank.ts
+++ b/packages/coding-agent/src/hindsight/bank.ts
@@ -1,5 +1,5 @@
 /**
- * Bank ID derivation, project-tag scoping, and first-use mission setup.
+ * Bank ID derivation, project-tag scoping, and first-use bank setup.
  *
  * Three scoping modes (`HindsightConfig.scoping`):
  *   - `global`              — single shared bank, no per-project filter.
@@ -11,10 +11,13 @@
  * The base bank id is `bankIdPrefix-bankId` (default `omp`). Per-project mode
  * appends `-<project>`; tagged mode leaves the bank untouched and uses tags.
  *
- * Mission setup is idempotent at module level — a missionsSet keeps track of
- * banks we've already POSTed to so each session boundary doesn't fire a fresh
- * `createBank` call. Failures are swallowed: missions are an optimisation, not
- * a precondition for retain/recall.
+ * Bank existence is idempotent at module level — a banksSet keeps track of
+ * banks we've already PUT so each session boundary doesn't fire a fresh
+ * `createBank` call. The PUT is idempotent server-side, so re-firing on a hot
+ * path would only burn round-trips. Failures are swallowed: missing the
+ * mission patch is an optimisation, but the bank ITSELF must exist before
+ * mental-model bootstrap or the first retain, otherwise the very first POST
+ * lands against a missing bank.
  */
 
 import * as path from "node:path";
@@ -93,39 +96,46 @@ export function deriveBankId(config: HindsightConfig, directory: string): string
 }
 
 /**
- * Ensure a bank's reflect/retain mission is set, exactly once per process.
+ * Ensure a bank exists, and patch its reflect/retain mission on first use.
  *
- * Tracked via the supplied set; on overflow we drop the oldest half so the set
- * cannot grow unboundedly across long-lived processes.
+ * Idempotent: skips the PUT when the bank id is already in the supplied set.
+ * The mission body is optional — when `bankMission` is blank we still PUT to
+ * make sure the bank itself is created, so mental-model bootstrap and the
+ * first retain don't land against a non-existent bank.
+ *
+ * The set is capped; on overflow we drop the oldest half so it cannot grow
+ * unboundedly across long-lived processes.
  */
-export async function ensureBankMission(
+export async function ensureBankExists(
 	client: HindsightApi,
 	bankId: string,
 	config: HindsightConfig,
-	missionsSet: Set<string>,
+	banksSet: Set<string>,
 ): Promise<void> {
+	if (banksSet.has(bankId)) return;
+
 	const mission = config.bankMission?.trim();
-	if (!mission) return;
-	if (missionsSet.has(bankId)) return;
+	const retainMission = config.retainMission?.trim();
 
 	try {
 		await client.createBank(bankId, {
-			reflectMission: mission,
-			retainMission: config.retainMission?.trim() || undefined,
+			reflectMission: mission || undefined,
+			retainMission: retainMission || undefined,
 		});
-		missionsSet.add(bankId);
-		if (missionsSet.size > MISSION_SET_CAP) {
-			const keys = [...missionsSet].sort();
+		banksSet.add(bankId);
+		if (banksSet.size > MISSION_SET_CAP) {
+			const keys = [...banksSet].sort();
 			for (const key of keys.slice(0, keys.length >> 1)) {
-				missionsSet.delete(key);
+				banksSet.delete(key);
 			}
 		}
 		if (config.debug) {
-			logger.debug("Hindsight: set mission for bank", { bankId });
+			logger.debug("Hindsight: ensured bank", { bankId, mission: Boolean(mission) });
 		}
 	} catch (err) {
-		// Mission set is best-effort; the bank may not exist yet, or the API may
-		// reject the call. Either way, retain/recall still work, so swallow.
-		logger.debug("Hindsight: ensureBankMission failed", { bankId, error: String(err) });
+		// Bank creation is best-effort; the server may already have it, or the
+		// API may reject the call. Either way, downstream retain/recall calls
+		// will surface a clearer error if the bank really is missing.
+		logger.debug("Hindsight: ensureBankExists failed", { bankId, error: String(err) });
 	}
 }
diff --git a/packages/coding-agent/src/hindsight/mental-models.ts b/packages/coding-agent/src/hindsight/mental-models.ts
index 294fb5fab..210137193 100644
--- a/packages/coding-agent/src/hindsight/mental-models.ts
+++ b/packages/coding-agent/src/hindsight/mental-models.ts
@@ -112,7 +112,7 @@ function dedupe<T>(items: T[]): T[] {
  * Idempotently create any seed mental models that don't already exist on the
  * bank. Best-effort: a list/create failure does not throw — mental models are
  * an optimization, not a precondition for retain/recall, and we mirror the
- * swallow-on-failure pattern used by `ensureBankMission`.
+ * swallow-on-failure pattern used by `ensureBankExists`.
  *
  * Existing models are NEVER modified. See module docstring.
  */
diff --git a/packages/coding-agent/src/hindsight/state.ts b/packages/coding-agent/src/hindsight/state.ts
index 883e5f714..26f3e7d58 100644
--- a/packages/coding-agent/src/hindsight/state.ts
+++ b/packages/coding-agent/src/hindsight/state.ts
@@ -1,6 +1,6 @@
 import { logger } from "@oh-my-pi/pi-utils";
 import type { AgentSession } from "../session/agent-session";
-import { type BankScope, ensureBankMission } from "./bank";
+import { type BankScope, ensureBankExists } from "./bank";
 import type { HindsightApi, MemoryItemInput } from "./client";
 import type { HindsightConfig } from "./config";
 import {
@@ -45,12 +45,12 @@ export interface HindsightSessionStateOptions {
 	recallTagsMatch?: "any" | "all" | "any_strict" | "all_strict";
 	config: HindsightConfig;
 	session: AgentSession;
-	missionsSet: Set<string>;
+	banksSet: Set<string>;
 	lastRetainedTurn?: number;
 	hasRecalledForFirstTurn?: boolean;
 	/**
 	 * When set, this entry is a subagent alias that reuses the parent's bank,
-	 * scope, config, client, and missionsSet. Aliases skip auto-recall and
+	 * scope, config, client, and banksSet. Aliases skip auto-recall and
 	 * auto-retain — those run on the parent only — but the recall/retain/reflect
 	 * tools resolve via the alias so they persist to the same bank as the parent.
 	 */
@@ -148,7 +148,7 @@ export class HindsightRetainQueue {
 		}
 
 		try {
-			await ensureBankMission(state.client, state.bankId, state.config, state.missionsSet);
+			await ensureBankExists(state.client, state.bankId, state.config, state.banksSet);
 			const batch: MemoryItemInput[] = items.map(item => ({
 				content: item.content,
 				context: item.context ?? state.config.retainContext,
@@ -198,7 +198,7 @@ export class HindsightSessionState {
 	recallTagsMatch?: "any" | "all" | "any_strict" | "all_strict";
 	config: HindsightConfig;
 	session: AgentSession;
-	missionsSet: Set<string>;
+	banksSet: Set<string>;
 	lastRetainedTurn: number;
 	hasRecalledForFirstTurn: boolean;
 	lastRecallSnippet?: string;
@@ -213,6 +213,12 @@ export class HindsightSessionState {
 	 */
 	mentalModelsLoadPromise?: Promise<void>;
 	unsubscribe?: () => void;
+	/**
+	 * Releases the `onHindsightScopeChanged` subscription that drives live
+	 * rebuilds when `hindsight.bankId` / `bankIdPrefix` / `scoping` change.
+	 * Only set on primary states; aliases inherit the parent's subscription.
+	 */
+	unsubscribeScope?: () => void;
 	/** Alias states delegate persistence config to a primary parent state. */
 	aliasOf?: HindsightSessionState;
 	readonly retainQueue: HindsightRetainQueue;
@@ -226,7 +232,7 @@ export class HindsightSessionState {
 		this.recallTagsMatch = options.recallTagsMatch;
 		this.config = options.config;
 		this.session = options.session;
-		this.missionsSet = options.missionsSet;
+		this.banksSet = options.banksSet;
 		this.lastRetainedTurn = options.lastRetainedTurn ?? 0;
 		this.hasRecalledForFirstTurn = options.hasRecalledForFirstTurn ?? false;
 		this.aliasOf = options.aliasOf;
@@ -291,7 +297,7 @@ export class HindsightSessionState {
 		const { transcript } = prepareRetentionTranscript(target, true);
 		if (!transcript) return;
 
-		await ensureBankMission(this.client, this.bankId, this.config, this.missionsSet);
+		await ensureBankExists(this.client, this.bankId, this.config, this.banksSet);
 		await this.client.retain(this.bankId, transcript, {
 			documentId,
 			context: this.config.retainContext,
@@ -398,6 +404,12 @@ export class HindsightSessionState {
 	async runMentalModelLoad(scope: BankScope): Promise<void> {
 		if (!this.config.mentalModelsEnabled) return;
 
+		// Create/ensure the bank BEFORE the first mental-model POST so we don't
+		// land `createMentalModel` against a bank the server has never seen —
+		// that surfaces as a FK / 404 on Hindsight's side. `ensureBankExists`
+		// is idempotent (PUT) and skips after the first call via `banksSet`.
+		await ensureBankExists(this.client, this.bankId, this.config, this.banksSet);
+
 		// Seeding is opt-in (`hindsight.mentalModelAutoSeed`). Default behaviour is
 		// read-only: we surface whatever models the operator has curated on the
 		// bank, but we do NOT POST to create new ones unless they explicitly
@@ -456,6 +468,8 @@ export class HindsightSessionState {
 	dispose(): void {
 		this.unsubscribe?.();
 		this.unsubscribe = undefined;
+		this.unsubscribeScope?.();
+		this.unsubscribeScope = undefined;
 		this.retainQueue.dispose();
 	}
 
diff --git a/packages/coding-agent/src/session/agent-session.ts b/packages/coding-agent/src/session/agent-session.ts
index b7760bb5c..d0ea75ac8 100644
--- a/packages/coding-agent/src/session/agent-session.ts
+++ b/packages/coding-agent/src/session/agent-session.ts
@@ -2990,8 +2990,13 @@ export class AgentSession {
 		this.#releasePowerAssertion();
 		await this.sessionManager.close();
 		this.#closeAllProviderSessions("dispose");
-		const hindsightState = this.setHindsightSessionState(undefined);
+		// Flush the retain queue BEFORE clearing the session's pointer so
+		// `HindsightRetainQueue.#doFlush` still sees `session.getHindsightSessionState() === state`.
+		// Reversed, the spliced batch survives just long enough to fail the
+		// identity check and get dropped with a `session vanished` warning.
+		const hindsightState = this.getHindsightSessionState();
 		await hindsightState?.flushRetainQueue();
+		this.setHindsightSessionState(undefined);
 		hindsightState?.dispose();
 		const mnemopiState = setMnemopiSessionState(this, undefined);
 		mnemopiState?.dispose();
diff --git a/packages/coding-agent/src/tools/memory-reflect.ts b/packages/coding-agent/src/tools/memory-reflect.ts
index 19e5fd2d3..8227a3328 100644
--- a/packages/coding-agent/src/tools/memory-reflect.ts
+++ b/packages/coding-agent/src/tools/memory-reflect.ts
@@ -1,7 +1,7 @@
 import type { AgentTool, AgentToolResult } from "@oh-my-pi/pi-agent-core";
 import { logger, untilAborted } from "@oh-my-pi/pi-utils";
 import * as z from "zod/v4";
-import { ensureBankMission } from "../hindsight/bank";
+import { ensureBankExists } from "../hindsight/bank";
 import reflectDescription from "../prompts/tools/reflect.md" with { type: "text" };
 import type { ToolSession } from ".";
 
@@ -67,7 +67,7 @@ export class MemoryReflectTool implements AgentTool<typeof memoryReflectSchema>
 			}
 
 			try {
-				await ensureBankMission(state.client, state.bankId, state.config, state.missionsSet);
+				await ensureBankExists(state.client, state.bankId, state.config, state.banksSet);
 				const response = await state.client.reflect(state.bankId, params.query, {
 					context: params.context,
 					budget: state.config.recallBudget,
diff --git a/packages/coding-agent/test/hindsight-backend.test.ts b/packages/coding-agent/test/hindsight-backend.test.ts
index 550306447..fbe17d9fe 100644
--- a/packages/coding-agent/test/hindsight-backend.test.ts
+++ b/packages/coding-agent/test/hindsight-backend.test.ts
@@ -19,6 +19,7 @@ interface FakeSessionDeps {
 	sessionId: string | null;
 	cwd?: string;
 	entries?: Array<{ role: "user" | "assistant"; text: string }>;
+	settings?: Settings;
 }
 
 function makeFakeSession(deps: FakeSessionDeps) {
@@ -27,7 +28,7 @@ function makeFakeSession(deps: FakeSessionDeps) {
 	let hindsightState: HindsightSessionState | undefined;
 	const session = {
 		sessionId: deps.sessionId,
-		settings: Settings.isolated(),
+		settings: deps.settings ?? Settings.isolated(),
 		sessionManager: {
 			getEntries: () =>
 				entries.map((e, i) => ({
@@ -207,7 +208,7 @@ describe("hindsightBackend.start", () => {
 		expect(subState?.aliasOf).toBe(parentState);
 		expect(subState?.bankId).toBe(parentState?.bankId);
 		expect(subState?.client).toBe(parentState?.client);
-		expect(subState?.missionsSet).toBe(parentState?.missionsSet);
+		expect(subState?.banksSet).toBe(parentState?.banksSet);
 		// Aliases must not subscribe to session events — the parent owns auto-recall/auto-retain.
 		expect(subState?.unsubscribe).toBeUndefined();
 		// hasRecalledForFirstTurn=true suppresses beforeAgentStartPrompt auto-recall on the sub.
@@ -532,3 +533,252 @@ describe("hindsightBackend.clear", () => {
 		expect(deleteSpy).not.toHaveBeenCalled();
 	});
 });
+
+describe("hindsightBackend live bank routing", () => {
+	beforeEach(() => {
+		resetSettingsForTest();
+	});
+
+	afterEach(() => {
+		vi.restoreAllMocks();
+	});
+
+	// Regression for issue #1902: changing `hindsight.bankId` during a live
+	// session used to leave the active `HindsightSessionState` pinned to the
+	// bank that was selected when the session started, so subsequent retains
+	// kept landing in the stale bank ("omp") instead of the new one
+	// ("Minigames"). The bank-routing settings must re-resolve on `set`.
+	it("rebuilds the primary state when hindsight.bankId changes mid-session", async () => {
+		vi.spyOn(HindsightApi.prototype, "createBank").mockResolvedValue({} as never);
+		const settings = Settings.isolated({
+			"memory.backend": "hindsight",
+			"hindsight.apiUrl": "http://localhost:8888",
+			"hindsight.scoping": "global",
+		});
+		// Seed bankId via `set` (not `isolated` overrides), otherwise the
+		// follow-up `set` writes to `#global` while `get` keeps returning the
+		// `#overrides` value — exactly the precedence the live settings UI
+		// does NOT have, since real config writes land in `#global`.
+		settings.set("hindsight.bankId", "omp");
+		const session = makeFakeSession({ sessionId: "s-rebuild", settings });
+
+		await hindsightBackend.start({
+			session: session as never,
+			settings,
+			modelRegistry: {} as never,
+			agentDir: "/tmp",
+			taskDepth: 0,
+		});
+
+		const initial = session.getHindsightSessionState();
+		expect(initial?.bankId).toBe("omp");
+
+		settings.set("hindsight.bankId", "Minigames");
+		// Hook is sync but the rebuild is async; yield once so the handler runs.
+		await Bun.sleep(0);
+
+		const next = session.getHindsightSessionState();
+		expect(next).toBeDefined();
+		expect(next?.bankId).toBe("Minigames");
+		// Must be a brand-new state — the old one was disposed.
+		expect(next).not.toBe(initial);
+	});
+
+	// Same regression, exercising the `hindsight.scoping` axis: switching
+	// scope mode also reshapes the bank id / tag filters and must rebuild.
+	it("rebuilds the primary state when hindsight.scoping changes mid-session", async () => {
+		vi.spyOn(HindsightApi.prototype, "createBank").mockResolvedValue({} as never);
+		const settings = Settings.isolated({
+			"memory.backend": "hindsight",
+			"hindsight.apiUrl": "http://localhost:8888",
+		});
+		settings.set("hindsight.scoping", "global");
+		const session = makeFakeSession({ sessionId: "s-scoping", cwd: "/work/proj", settings });
+
+		await hindsightBackend.start({
+			session: session as never,
+			settings,
+			modelRegistry: {} as never,
+			agentDir: "/tmp",
+			taskDepth: 0,
+		});
+
+		const initial = session.getHindsightSessionState();
+		expect(initial?.bankId).toBe("omp");
+		expect(initial?.retainTags).toBeUndefined();
+
+		settings.set("hindsight.scoping", "per-project");
+		await Bun.sleep(0);
+
+		const next = session.getHindsightSessionState();
+		expect(next).toBeDefined();
+		expect(next?.bankId).toBe("omp-proj");
+		expect(next).not.toBe(initial);
+	});
+
+	// Same setting written with the same value MUST NOT rebuild — a rebuild
+	// would reset `lastRetainedTurn` / `hasRecalledForFirstTurn` and force a
+	// fresh mental-model bootstrap for no observable reason.
+	it("does not rebuild when the bank-routing setting is rewritten with the same value", async () => {
+		vi.spyOn(HindsightApi.prototype, "createBank").mockResolvedValue({} as never);
+		const settings = Settings.isolated({
+			"memory.backend": "hindsight",
+			"hindsight.apiUrl": "http://localhost:8888",
+		});
+		settings.set("hindsight.bankId", "omp");
+		const session = makeFakeSession({ sessionId: "s-noop", settings });
+
+		await hindsightBackend.start({
+			session: session as never,
+			settings,
+			modelRegistry: {} as never,
+			agentDir: "/tmp",
+			taskDepth: 0,
+		});
+
+		const initial = session.getHindsightSessionState();
+		settings.set("hindsight.bankId", "omp"); // unchanged
+		await Bun.sleep(0);
+
+		expect(session.getHindsightSessionState()).toBe(initial);
+	});
+
+	// Regression for issue #1902 fix #2: mental-model auto-seed used to POST
+	// `createMentalModel` against a bank the server never saw, because the
+	// old `ensureBankMission` skipped creation entirely when `bankMission`
+	// was blank. The bank MUST be PUT (created) before any mental-model POST.
+	it("creates the bank before mental-model bootstrap even when bankMission is blank", async () => {
+		const callOrder: string[] = [];
+		const createBankSpy = vi.spyOn(HindsightApi.prototype, "createBank").mockImplementation(async () => {
+			callOrder.push("createBank");
+			return {} as never;
+		});
+		const listMentalSpy = vi.spyOn(HindsightApi.prototype, "listMentalModels").mockImplementation(async () => {
+			callOrder.push("listMentalModels");
+			return { items: [] } as never;
+		});
+		const createMentalModelSpy = vi
+			.spyOn(HindsightApi.prototype, "createMentalModel")
+			.mockImplementation(async () => {
+				callOrder.push("createMentalModel");
+				return {} as never;
+			});
+
+		const settings = Settings.isolated({
+			"memory.backend": "hindsight",
+			"hindsight.apiUrl": "http://localhost:8888",
+			"hindsight.mentalModelsEnabled": true,
+			"hindsight.mentalModelAutoSeed": true,
+			"hindsight.bankMission": "",
+		});
+		const session = makeFakeSession({ sessionId: "s-bank-first", settings });
+
+		await hindsightBackend.start({
+			session: session as never,
+			settings,
+			modelRegistry: {} as never,
+			agentDir: "/tmp",
+			taskDepth: 0,
+		});
+		await session.getHindsightSessionState()?.mentalModelsLoadPromise;
+
+		expect(createBankSpy).toHaveBeenCalled();
+		// First call must be `createBank`. Otherwise the mental-model POST
+		// lands against a never-created bank and the server FK-fails it.
+		expect(callOrder[0]).toBe("createBank");
+		// Mental-model POSTs are allowed but they MUST come after the bank
+		// is on the server.
+		if (createMentalModelSpy.mock.calls.length > 0) {
+			const bankIdx = callOrder.indexOf("createBank");
+			const mmIdx = callOrder.indexOf("createMentalModel");
+			expect(bankIdx).toBeLessThan(mmIdx);
+		}
+		void listMentalSpy;
+	});
+});
+
+describe("hindsightBackend retain queue flush on session teardown", () => {
+	beforeEach(() => {
+		resetSettingsForTest();
+	});
+
+	afterEach(() => {
+		vi.restoreAllMocks();
+	});
+
+	// Regression for issue #1902 fix #3: `AgentSession.dispose` used to clear
+	// `#hindsightSessionState` BEFORE flushing the retain queue, so
+	// `HindsightRetainQueue.#doFlush` saw `session.getHindsightSessionState()
+	// !== state` and dropped the spliced batch. The fix flips the order:
+	// flush MUST complete while the session pointer still references the same
+	// state. We defend the contract end-to-end by enqueuing a tool-initiated
+	// retain, then calling `flushRetainQueue` in the order
+	// `AgentSession.dispose` uses (flush → clear → state.dispose).
+	it("flushes the retain queue to the server before the session pointer clears", async () => {
+		const retainBatchSpy = vi.spyOn(HindsightApi.prototype, "retainBatch").mockResolvedValue({} as never);
+		vi.spyOn(HindsightApi.prototype, "createBank").mockResolvedValue({} as never);
+
+		const settings = Settings.isolated({
+			"memory.backend": "hindsight",
+			"hindsight.apiUrl": "http://localhost:8888",
+			"hindsight.bankId": "omp",
+		});
+		const session = makeFakeSession({ sessionId: "s-dispose-flush", settings });
+
+		await hindsightBackend.start({
+			session: session as never,
+			settings,
+			modelRegistry: {} as never,
+			agentDir: "/tmp",
+			taskDepth: 0,
+		});
+		const state = session.getHindsightSessionState();
+		expect(state).toBeDefined();
+
+		state!.enqueueRetain("durable fact", "test context");
+
+		// AgentSession.dispose order: flush first, THEN clear, THEN dispose.
+		// Reversed (clear → flush), `#doFlush`'s identity check would fail and
+		// the batch would be dropped with a `session vanished` warning.
+		await state!.flushRetainQueue();
+		session.setHindsightSessionState(undefined);
+		state!.dispose();
+
+		expect(retainBatchSpy).toHaveBeenCalledTimes(1);
+		const [bankId, items] = retainBatchSpy.mock.calls[0];
+		expect(bankId).toBe("omp");
+		expect(items).toHaveLength(1);
+		expect(items[0].content).toBe("durable fact");
+	});
+
+	// Companion contract test: documents the failure mode the dispose-order
+	// fix prevents. If the session pointer is cleared first, the queue's
+	// identity guard drops the spliced batch (and `retainBatch` is NOT
+	// called). This is exactly what was happening before the fix.
+	it("drops the spliced batch when the session pointer is cleared before flush (anti-regression)", async () => {
+		const retainBatchSpy = vi.spyOn(HindsightApi.prototype, "retainBatch").mockResolvedValue({} as never);
+		vi.spyOn(HindsightApi.prototype, "createBank").mockResolvedValue({} as never);
+
+		const settings = Settings.isolated({
+			"memory.backend": "hindsight",
+			"hindsight.apiUrl": "http://localhost:8888",
+		});
+		const session = makeFakeSession({ sessionId: "s-buggy-order", settings });
+
+		await hindsightBackend.start({
+			session: session as never,
+			settings,
+			modelRegistry: {} as never,
+			agentDir: "/tmp",
+			taskDepth: 0,
+		});
+		const state = session.getHindsightSessionState();
+		state!.enqueueRetain("dropped fact");
+
+		// Buggy order — clear THEN flush. The queue's identity check fails.
+		session.setHindsightSessionState(undefined);
+		await state!.flushRetainQueue();
+
+		expect(retainBatchSpy).not.toHaveBeenCalled();
+	});
+});
diff --git a/packages/coding-agent/test/hindsight-bank.test.ts b/packages/coding-agent/test/hindsight-bank.test.ts
index bbda61602..0ce81b792 100644
--- a/packages/coding-agent/test/hindsight-bank.test.ts
+++ b/packages/coding-agent/test/hindsight-bank.test.ts
@@ -1,5 +1,5 @@
 import { afterEach, beforeEach, describe, expect, it, type Mock, vi } from "bun:test";
-import { computeBankScope, deriveBankId, ensureBankMission } from "@oh-my-pi/pi-coding-agent/hindsight/bank";
+import { computeBankScope, deriveBankId, ensureBankExists } from "@oh-my-pi/pi-coding-agent/hindsight/bank";
 import { HindsightApi } from "@oh-my-pi/pi-coding-agent/hindsight/client";
 import type { HindsightConfig } from "@oh-my-pi/pi-coding-agent/hindsight/config";
 
@@ -117,7 +117,7 @@ describe("deriveBankId (legacy wrapper)", () => {
 	});
 });
 
-describe("ensureBankMission", () => {
+describe("ensureBankExists", () => {
 	let client: HindsightApi;
 	let createSpy: Mock<HindsightApi["createBank"]> | undefined;
 
@@ -129,14 +129,14 @@ describe("ensureBankMission", () => {
 		createSpy?.mockRestore();
 	});
 
-	it("calls createBank exactly once per bank id", async () => {
+	it("calls createBank exactly once per bank id and forwards the mission body", async () => {
 		createSpy = vi.spyOn(HindsightApi.prototype, "createBank").mockResolvedValue({} as never);
 		const seen = new Set<string>();
 		const config = baseConfig({ bankMission: "remember everything", retainMission: "extract facts" });
 
-		await ensureBankMission(client, "bank-a", config, seen);
-		await ensureBankMission(client, "bank-a", config, seen);
-		await ensureBankMission(client, "bank-b", config, seen);
+		await ensureBankExists(client, "bank-a", config, seen);
+		await ensureBankExists(client, "bank-a", config, seen);
+		await ensureBankExists(client, "bank-b", config, seen);
 
 		expect(createSpy).toHaveBeenCalledTimes(2);
 		expect(createSpy).toHaveBeenCalledWith(
@@ -148,13 +148,22 @@ describe("ensureBankMission", () => {
 		expect(seen.has("bank-b")).toBe(true);
 	});
 
-	it("is a no-op when no mission is configured", async () => {
+	// Regression: mental-model auto-seed used to POST `createMentalModel` against
+	// a never-created bank when `bankMission` was blank, because the old
+	// `ensureBankMission` skipped creation entirely without a mission.
+	it("still PUTs the bank when no mission is configured (so the bank gets created)", async () => {
 		createSpy = vi.spyOn(HindsightApi.prototype, "createBank").mockResolvedValue({} as never);
 		const seen = new Set<string>();
-		await ensureBankMission(client, "bank", baseConfig({ bankMission: "" }), seen);
-		await ensureBankMission(client, "bank", baseConfig({ bankMission: "   " }), seen);
-		expect(createSpy).not.toHaveBeenCalled();
-		expect(seen.size).toBe(0);
+
+		await ensureBankExists(client, "bank", baseConfig({ bankMission: "" }), seen);
+		await ensureBankExists(client, "bank", baseConfig({ bankMission: "   " }), seen);
+
+		expect(createSpy).toHaveBeenCalledTimes(1);
+		expect(createSpy).toHaveBeenCalledWith(
+			"bank",
+			expect.objectContaining({ reflectMission: undefined, retainMission: undefined }),
+		);
+		expect(seen.has("bank")).toBe(true);
 	});
 
 	it("swallows API failures and does not mark the bank as initialised", async () => {
@@ -162,7 +171,7 @@ describe("ensureBankMission", () => {
 		const seen = new Set<string>();
 		const config = baseConfig({ bankMission: "do the thing" });
 
-		await expect(ensureBankMission(client, "bank-x", config, seen)).resolves.toBeUndefined();
+		await expect(ensureBankExists(client, "bank-x", config, seen)).resolves.toBeUndefined();
 		expect(seen.has("bank-x")).toBe(false);
 	});
 });
diff --git a/packages/coding-agent/test/memory-tools.test.ts b/packages/coding-agent/test/memory-tools.test.ts
index bd9da3a22..9875bf69d 100644
--- a/packages/coding-agent/test/memory-tools.test.ts
+++ b/packages/coding-agent/test/memory-tools.test.ts
@@ -100,7 +100,7 @@ function registerState(client: HindsightApi, settings?: Settings, opts: Register
 			getHindsightSessionState: () => registeredState,
 			...opts.sessionOverrides,
 		} as never,
-		missionsSet: new Set(),
+		banksSet: new Set(),
 		lastRetainedTurn: 0,
 		hasRecalledForFirstTurn: false,
 	});