refactor(agent): let runner own context compaction (#5568)

* refactor(agent): consolidate accepted history under pressure

* fix(agent): align provider and session compaction

* refactor(agent): simplify runner context compaction

* refactor(agent): remove background token consolidation

* fix(agent): keep injected transcript messages distinct

* refactor(agent): unify native compaction summaries

* fix(agent): preserve native compaction boundary

* fix(agent): unify context compaction paths

* fix(agent): preserve exact compaction request boundaries

webui/src/lib/types.ts

@@ -714,7 +714,6 @@ export interface SettingsPayload {
     heartbeat: {
       enabled: boolean;
       interval_s: number;
-      keep_recent_messages: number;
     };
     dream: {
       schedule: string;

webui/src/tests/app-layout.test.tsx

@@ -131,7 +131,6 @@ function baseSettingsPayload() {
       heartbeat: {
         enabled: true,
         interval_s: 1800,
-        keep_recent_messages: 8,
       },
       dream: {
         schedule: "every 2h",
@@ -2470,7 +2469,6 @@ describe("App layout", () => {
                 heartbeat: {
                   enabled: true,
                   interval_s: 1800,
-                  keep_recent_messages: 8,
                 },
                 dream: {
                   schedule: "every 2h",
@@ -2960,7 +2958,6 @@ describe("App layout", () => {
                 heartbeat: {
                   enabled: true,
                   interval_s: 1800,
-                  keep_recent_messages: 8,
                 },
                 dream: {
                   schedule: "every 2h",

webui/src/tests/settings-test-utils.tsx

@@ -91,7 +91,6 @@ export function settingsPayload(): SettingsPayload {
       heartbeat: {
         enabled: true,
         interval_s: 1800,
-        keep_recent_messages: 8,
       },
       dream: {
         schedule: "every 2h",

webui/src/tests/thread-shell.test.tsx

@@ -368,7 +368,6 @@ function modelSettings(model: string, provider: string): SettingsPayload {
       heartbeat: {
         enabled: true,
         interval_s: 1800,
-        keep_recent_messages: 8,
       },
       dream: {
         schedule: "every 2h",