diff --git a/.changeset/session-tfg-source-backfill.md b/.changeset/session-tfg-source-backfill.md
new file mode 100644
index 000000000..27c3c650b
--- /dev/null
+++ b/.changeset/session-tfg-source-backfill.md
@@ -0,0 +1,5 @@
+---
+"@truefoundry/trueforge": patch
+---
+
+Backfill `tfg.source: ui` session metadata on existing non-scheduled sessions so they stay in Chat History once it filters on that key.
diff --git a/packages/trueforge/src/db/indexes.ts b/packages/trueforge/src/db/indexes.ts
index e69c9757a..d848e5156 100644
--- a/packages/trueforge/src/db/indexes.ts
+++ b/packages/trueforge/src/db/indexes.ts
@@ -16,6 +16,12 @@ export const AGENT_EXTERNAL_ID_UQ = 'agent_external_id_uq';
 /** GIN index for `session.metadata` containment queries (`@>`). */
 export const SESSION_METADATA_GIN = 'session_metadata_gin';
 
+/**
+ * `(tenant_id, created_by_subject.subject_id, updated_at, session_id, metadata.tfg.source)` on
+ * session — a caller's sessions in keyset order, optionally filtered by `tfg.source`.
+ */
+export const SESSION_TFG_SOURCE_LIST_IDX = 'session_tfg_source_list_idx';
+
 /** `(tenant_id, created_by_subject.subject_id)` on agent. */
 export const AGENT_CREATED_BY_SUBJECT_ID_IDX = 'agent_created_by_subject_id_idx';
 
diff --git a/packages/trueforge/src/db/postgres/migrations/20261022_000001_session_tfg_source_backfill.ts b/packages/trueforge/src/db/postgres/migrations/20261022_000001_session_tfg_source_backfill.ts
new file mode 100644
index 000000000..b20441551
--- /dev/null
+++ b/packages/trueforge/src/db/postgres/migrations/20261022_000001_session_tfg_source_backfill.ts
@@ -0,0 +1,26 @@
+import { sql, type Kysely } from 'kysely';
+
+/**
+ * Stamp `metadata["tfg.source"] = "ui"` on pre-existing interactive sessions so Chat History,
+ * which now lists only sessions carrying that key, keeps showing them.
+ *
+ * Schedule runs are the only sessions with `external_id`; checking it alongside `source` also
+ * skips schedule runs created before `source` existed. `updated_at` is left untouched so list
+ * ordering does not change.
+ */
+export async function up<TDatabase>(db: Kysely<TDatabase>): Promise<void> {
+  await sql`SET LOCAL lock_timeout = '5s'`.execute(db);
+  await sql`
+    UPDATE session
+    SET metadata = metadata || jsonb_build_object('tfg.source', 'ui')
+    WHERE source IS NULL
+      AND external_id IS NULL
+      AND metadata->'tfg.source' IS NULL
+  `.execute(db);
+}
+
+/** Data backfill — not reversed: backfilled rows are indistinguishable from UI-stamped ones. */
+export function down(db: Kysely<unknown>): Promise<void> {
+  void db;
+  return Promise.reject(new Error('20261022_000001_session_tfg_source_backfill is irreversible'));
+}
diff --git a/packages/trueforge/src/db/postgres/migrations/20261022_000002_session_tfg_source_list_idx.ts b/packages/trueforge/src/db/postgres/migrations/20261022_000002_session_tfg_source_list_idx.ts
new file mode 100644
index 000000000..eab4bf28c
--- /dev/null
+++ b/packages/trueforge/src/db/postgres/migrations/20261022_000002_session_tfg_source_list_idx.ts
@@ -0,0 +1,25 @@
+import { sql, type Kysely } from 'kysely';
+import { SESSION_TFG_SOURCE_LIST_IDX } from '../../indexes';
+
+/**
+ * A caller's sessions in keyset order, so their newest-first listing needs no sort with or without
+ * a `tfg.source` filter; the filter is checked on index entries without visiting the table.
+ */
+export async function up(db: Kysely<unknown>): Promise<void> {
+  await sql`SET LOCAL lock_timeout = '5s'`.execute(db);
+  await sql`
+    CREATE INDEX ${sql.raw(SESSION_TFG_SOURCE_LIST_IDX)}
+      ON session (
+        tenant_id,
+        (created_by_subject->>'subject_id'),
+        updated_at,
+        session_id,
+        (metadata->>'tfg.source')
+      )
+  `.execute(db);
+}
+
+export async function down(db: Kysely<unknown>): Promise<void> {
+  await sql`SET LOCAL lock_timeout = '5s'`.execute(db);
+  await sql`DROP INDEX IF EXISTS ${sql.raw(SESSION_TFG_SOURCE_LIST_IDX)}`.execute(db);
+}
diff --git a/packages/trueforge/src/db/postgres/session-store/queries/sessions.ts b/packages/trueforge/src/db/postgres/session-store/queries/sessions.ts
index 2b998e226..b6f5e890a 100644
--- a/packages/trueforge/src/db/postgres/session-store/queries/sessions.ts
+++ b/packages/trueforge/src/db/postgres/session-store/queries/sessions.ts
@@ -285,6 +285,12 @@ export async function listSessions(
       query = query.where(sql<boolean>`metadata = '{}'::jsonb`);
     } else {
       query = query.where(sql<boolean>`metadata @> ${json(input.metadata)}`);
+      // Matches the same rows as the `@>` filter above (metadata values are always strings).
+      // Postgres can only use the GIN index for `@>`; spelling each pair as `metadata->>'key' = value`
+      // also lets it use single-key indexes. Those match on the literal key, so it is inlined, not bound.
+      for (const [key, value] of Object.entries(input.metadata)) {
+        query = query.where(sql<string>`metadata->>${sql.lit(key)}`, '=', value);
+      }
     }
   }
   if (input.source_type !== undefined) {
diff --git a/packages/trueforge/src/db/sqlite/migrations/20261022_000001_session_tfg_source_backfill.ts b/packages/trueforge/src/db/sqlite/migrations/20261022_000001_session_tfg_source_backfill.ts
new file mode 100644
index 000000000..3441ab719
--- /dev/null
+++ b/packages/trueforge/src/db/sqlite/migrations/20261022_000001_session_tfg_source_backfill.ts
@@ -0,0 +1,22 @@
+import { sql, type Kysely } from 'kysely';
+
+/**
+ * SQLite mirror of postgres/migrations/20261022_000001_session_tfg_source_backfill.ts.
+ */
+export async function up<TDatabase>(db: Kysely<TDatabase>): Promise<void> {
+  await db.transaction().execute(async trx => {
+    await sql`
+      UPDATE session
+      SET metadata = jsonb_set(metadata, '$."tfg.source"', 'ui')
+      WHERE source IS NULL
+        AND external_id IS NULL
+        AND json_extract(metadata, '$."tfg.source"') IS NULL
+    `.execute(trx);
+  });
+}
+
+/** Data backfill — not reversed: backfilled rows are indistinguishable from UI-stamped ones. */
+export function down(db: Kysely<unknown>): Promise<void> {
+  void db;
+  return Promise.reject(new Error('20261022_000001_session_tfg_source_backfill is irreversible'));
+}
diff --git a/packages/trueforge/src/db/sqlite/migrations/20261022_000002_session_tfg_source_list_idx.ts b/packages/trueforge/src/db/sqlite/migrations/20261022_000002_session_tfg_source_list_idx.ts
new file mode 100644
index 000000000..18b5e9fbf
--- /dev/null
+++ b/packages/trueforge/src/db/sqlite/migrations/20261022_000002_session_tfg_source_list_idx.ts
@@ -0,0 +1,27 @@
+import { sql, type Kysely } from 'kysely';
+import { SESSION_TFG_SOURCE_LIST_IDX } from '../../indexes';
+
+/**
+ * SQLite mirror of postgres/migrations/20261022_000002_session_tfg_source_list_idx.ts.
+ * The key contains a dot, so the JSON path must quote it.
+ */
+export async function up(db: Kysely<unknown>): Promise<void> {
+  await db.transaction().execute(async trx => {
+    await sql`
+      CREATE INDEX ${sql.raw(SESSION_TFG_SOURCE_LIST_IDX)}
+        ON session (
+          tenant_id,
+          json_extract(created_by_subject, '$.subject_id'),
+          updated_at,
+          session_id,
+          json_extract(metadata, '$."tfg.source"')
+        )
+    `.execute(trx);
+  });
+}
+
+export async function down(db: Kysely<unknown>): Promise<void> {
+  await db.transaction().execute(async trx => {
+    await sql`DROP INDEX IF EXISTS ${sql.raw(SESSION_TFG_SOURCE_LIST_IDX)}`.execute(trx);
+  });
+}