fix(test): 容量合同按 fixture.psql 的 f: 字母表断言（BUG-739）

Independent Staging Quality Gate run 2683 唯一失败：
database-consultation-session-capacity 期望 false:session_missing，
实际是 f:session_missing。夹具把 boolean::text 的 false 规范成 psql -A 的 f。
五处期望值对齐既有合同；无 Docker 源码合同锁住 false→f。

frontend/tests/consultation-session-capacity.test.ts

@@ -22,6 +22,14 @@ const consultRoute = readFileSync(
   new URL("../src/app/api/consult/route.ts", import.meta.url),
   "utf8",
 );
+const databaseCapacityTest = readFileSync(
+  new URL("./database-consultation-session-capacity.test.ts", import.meta.url),
+  "utf8",
+);
+const postgresFixture = readFileSync(
+  new URL("./helpers/postgres-fixture.ts", import.meta.url),
+  "utf8",
+);
 
 const SESSION_SELECT =
   "id,title,theme,model_id,messages,session_type,rectification_case_id,chart_profile_id,chart_profile_name,chart_profile_role,updated_at,pinned,archived_at";
@@ -286,3 +294,16 @@ test("session-detail JSON at the old ~19-round cap versus the new ~50-round cap"
     `50/19 size ratio was ${ratio.toFixed(3)} (utf8 ${oldBytes} → ${newBytes})`,
   );
 });
+
+test("live Postgres capacity assertions use fixture.psql's false→f alphabet (BUG-739)", () => {
+  assert.match(
+    postgresFixture,
+    /\.replace\(\/\(\^|:\)false\(\?=:|\$\)\/gm, "\$1f"\)/,
+  );
+  assert.match(databaseCapacityTest, /"f:session_missing"/);
+  assert.match(databaseCapacityTest, /"f:invalid_question_message"/);
+  assert.equal((databaseCapacityTest.match(/"f:session_full"/g) ?? []).length, 3);
+  assert.doesNotMatch(databaseCapacityTest, /"false:session_missing"/);
+  assert.doesNotMatch(databaseCapacityTest, /"false:invalid_question_message"/);
+  assert.doesNotMatch(databaseCapacityTest, /"false:session_full"/);
+});

frontend/tests/database-consultation-session-capacity.test.ts

@@ -119,7 +119,7 @@ test("append_consultation_question ignores thinking fields and enforces the phys
 
     assert.equal(
       appendQuestion(fixture, userId, "missing-session", "会话不存在"),
-      "false:session_missing",
+      "f:session_missing",
     );
 
     seedSession(fixture, userId, "'[]'::jsonb");
@@ -132,7 +132,7 @@ test("append_consultation_question ignores thinking fields and enforces the phys
 
     assert.equal(
       appendQuestionSql(fixture, userId, "too-long", "repeat('x', 16001)"),
-      "false:invalid_question_message",
+      "f:invalid_question_message",
     );
 
     seedSession(fixture, userId, `
@@ -215,7 +215,7 @@ test("append_consultation_question ignores thinking fields and enforces the phys
     assert.ok(quotaPhysical < 1_000_000, `quota-boundary physical JSON was ${quotaPhysical}`);
     assert.equal(
       appendQuestionSql(fixture, userId, "quota-full", "repeat('y', 1001)"),
-      "false:session_full",
+      "f:session_full",
     );
     assert.equal(
       fixture.psql(`select jsonb_array_length(messages) from public.chat_sessions where id = '${SESSION_ID}'`),
@@ -247,7 +247,7 @@ test("append_consultation_question ignores thinking fields and enforces the phys
     assert.ok(hugePhysical > 1_000_000, `receipt pad physical JSON was ${hugePhysical}`);
     assert.equal(
       appendQuestion(fixture, userId, "physical-full", "正文很短但行已经胀了"),
-      "false:session_full",
+      "f:session_full",
     );
     assert.equal(
       fixture.psql(`select jsonb_array_length(messages) from public.chat_sessions where id = '${SESSION_ID}'`),
@@ -265,7 +265,7 @@ test("append_consultation_question ignores thinking fields and enforces the phys
     `);
     assert.equal(
       appendQuestion(fixture, userId, "count-full", "满了就不能再写"),
-      "false:session_full",
+      "f:session_full",
     );
     assert.equal(
       fixture.psql(`select jsonb_array_length(messages) from public.chat_sessions where id = '${SESSION_ID}'`),

frontend/tests/helpers/postgres-fixture.ts

@@ -243,6 +243,8 @@ export function startPostgresFixture(): PostgresFixture {
         { encoding: "utf8", env: environment },
       )
         .trim()
+        // boolean::text is "false"; psql -A prints "f". Keep colon-joined
+        // results on the t/f alphabet so tests can assert "f:" stably.
         .replace(/(^|:)false(?=:|$)/gm, "$1f");
     },
     psqlAs(role, password, sql) {