diff --git a/.openclaw-sync/source.json b/.openclaw-sync/source.json
index 2ed9860ff..d343bc74a 100644
--- a/.openclaw-sync/source.json
+++ b/.openclaw-sync/source.json
@@ -1,5 +1,5 @@
 {
   "repository": "openclaw/openclaw",
-  "sha": "ad85e5c64ca0d93302c920d3cfedc1c9b05a67a3",
-  "syncedAt": "2026-05-02T05:57:38.575Z"
+  "sha": "267f5e081ab0ea877eac748ac219e9df49416b8b",
+  "syncedAt": "2026-05-02T05:59:17.827Z"
 }
diff --git a/docs/.generated/config-baseline.sha256 b/docs/.generated/config-baseline.sha256
index 3e953061d..23c54309d 100644
--- a/docs/.generated/config-baseline.sha256
+++ b/docs/.generated/config-baseline.sha256
@@ -1,4 +1,4 @@
-94f7879b0771e81973c0749c719c19283fdc26e0e42fe6536f8ee563be6a44e5  config-baseline.json
-a38ea77d2f0f0188f14ce0e3a8a564ff80e51415849359042f51921eb01ec2d9  config-baseline.core.json
-eab8a85eefa2792fb8b98a07698e5ec31ff0b6f8af6222767e8049dcc5c4f529  config-baseline.channel.json
-6bd6c72b17801072b2d3285c82f4c21adcc95f0edffc1e6f64e767d0a07b678f  config-baseline.plugin.json
+0020a49cdf07b79fddfed9584f10323ef77e3ca5c7f907d441c1f2e3f45932c9  config-baseline.json
+8193fd771c9fa50e77c71ff69d41015e6dc02d140182ceea3baaa17713f04b18  config-baseline.core.json
+f42329d45c095881bd226bdb192c235980658fd250606d0c0badc2b12f12f5d3  config-baseline.channel.json
+af71b84b2411d8ccabcc6e09de0ee41f8212ff9869a6677698b6e7e3afdfaa47  config-baseline.plugin.json
diff --git a/docs/channels/discord.md b/docs/channels/discord.md
index e1d7cd38b..ac324dcd4 100644
--- a/docs/channels/discord.md
+++ b/docs/channels/discord.md
@@ -738,7 +738,8 @@ Default slash command settings:
         enabled: true,
         idleHours: 24,
         maxAgeHours: 0,
-        spawnSubagentSessions: false, // opt-in
+        spawnSessions: true,
+        defaultSpawnContext: "fork",
       },
     },
   },
@@ -749,8 +750,9 @@ Default slash command settings:
 
     - `session.threadBindings.*` sets global defaults.
     - `channels.discord.threadBindings.*` overrides Discord behavior.
-    - `spawnSubagentSessions` must be true to auto-create/bind threads for `sessions_spawn({ thread: true })`.
-    - `spawnAcpSessions` must be true to auto-create/bind threads for ACP (`/acp spawn ... --thread ...` or `sessions_spawn({ runtime: "acp", thread: true })`).
+    - `spawnSessions` controls auto-create/bind threads for `sessions_spawn({ thread: true })` and ACP thread spawns. Default: `true`.
+    - `defaultSpawnContext` controls native subagent context for thread-bound spawns. Default: `"fork"`.
+    - Deprecated `spawnSubagentSessions`/`spawnAcpSessions` keys are migrated by `openclaw doctor --fix`.
     - If thread bindings are disabled for an account, `/focus` and related thread binding operations are unavailable.
 
     See [Sub-agents](/tools/subagents), [ACP Agents](/tools/acp-agents), and [Configuration Reference](/gateway/configuration-reference).
@@ -816,7 +818,7 @@ Default slash command settings:
 
     - `/acp spawn codex --bind here` binds the current channel or thread in place and keeps future messages on the same ACP session. Thread messages inherit the parent channel binding.
     - In a bound channel or thread, `/new` and `/reset` reset the same ACP session in place. Temporary thread bindings can override target resolution while active.
-    - `spawnAcpSessions` is only required when OpenClaw needs to create/bind a child thread via `--thread auto|here`.
+    - `spawnSessions` gates child thread creation/binding via `--thread auto|here`.
 
     See [ACP Agents](/tools/acp-agents) for binding behavior details.
 
diff --git a/docs/channels/matrix.md b/docs/channels/matrix.md
index 361eaa6b5..65698fd61 100644
--- a/docs/channels/matrix.md
+++ b/docs/channels/matrix.md
@@ -530,7 +530,7 @@ Explicit conversation bindings always win over `sessionScope`, so bound rooms an
 - Message-tool sends auto-inherit the current Matrix thread when targeting the same room (or the same DM user target), unless an explicit `threadId` is provided.
 - DM user-target reuse only kicks in when the current session metadata proves the same DM peer on the same Matrix account; otherwise OpenClaw falls back to normal user-scoped routing.
 - `/focus`, `/unfocus`, `/agents`, `/session idle`, `/session max-age`, and thread-bound `/acp spawn` all work in Matrix rooms and DMs.
-- Top-level `/focus` creates a new Matrix thread and binds it to the target session when `threadBindings.spawnSubagentSessions: true`.
+- Top-level `/focus` creates a new Matrix thread and binds it to the target session when `threadBindings.spawnSessions` is enabled.
 - Running `/focus` or `/acp spawn --thread here` inside an existing Matrix thread binds that thread in place.
 
 When OpenClaw detects a Matrix DM room colliding with another DM room on the same shared session, it posts a one-time `m.notice` in that room pointing to the `/focus` escape hatch and suggesting a `dm.sessionScope` change. The notice only appears when thread bindings are enabled.
@@ -550,7 +550,7 @@ Fast operator flow:
 Notes:
 
 - `--bind here` does not create a child Matrix thread.
-- `threadBindings.spawnAcpSessions` is only required for `/acp spawn --thread auto|here`, where OpenClaw needs to create or bind a child Matrix thread.
+- `threadBindings.spawnSessions` gates `/acp spawn --thread auto|here`, where OpenClaw needs to create or bind a child Matrix thread.
 
 ### Thread binding config
 
@@ -559,13 +559,13 @@ Matrix inherits global defaults from `session.threadBindings`, and also supports
 - `threadBindings.enabled`
 - `threadBindings.idleHours`
 - `threadBindings.maxAgeHours`
-- `threadBindings.spawnSubagentSessions`
-- `threadBindings.spawnAcpSessions`
+- `threadBindings.spawnSessions`
+- `threadBindings.defaultSpawnContext`
 
-Matrix thread-bound spawn flags are opt-in:
+Matrix thread-bound session spawns default on:
 
-- Set `threadBindings.spawnSubagentSessions: true` to allow top-level `/focus` to create and bind new Matrix threads.
-- Set `threadBindings.spawnAcpSessions: true` to allow `/acp spawn --thread auto|here` to bind ACP sessions to Matrix threads.
+- Set `threadBindings.spawnSessions: false` to block top-level `/focus` and `/acp spawn --thread auto|here` from creating/binding Matrix threads.
+- Set `threadBindings.defaultSpawnContext: "isolated"` when native subagent thread spawns should not fork the parent transcript.
 
 ## Reactions
 
diff --git a/docs/channels/telegram.md b/docs/channels/telegram.md
index 599aa25ec..9f969df23 100644
--- a/docs/channels/telegram.md
+++ b/docs/channels/telegram.md
@@ -540,7 +540,7 @@ curl "https://api.telegram.org/bot<bot_token>/getUpdates"
 
     **Persistent ACP topic binding**: Forum topics can pin ACP harness sessions through top-level typed ACP bindings (`bindings[]` with `type: "acp"` and `match.channel: "telegram"`, `peer.kind: "group"`, and a topic-qualified id like `-1001234567890:topic:42`). Currently scoped to forum topics in groups/supergroups. See [ACP Agents](/tools/acp-agents).
 
-    **Thread-bound ACP spawn from chat**: `/acp spawn <agent> --thread here|auto` binds the current topic to a new ACP session; follow-ups route there directly. OpenClaw pins the spawn confirmation in-topic. Requires `channels.telegram.threadBindings.spawnAcpSessions=true`.
+    **Thread-bound ACP spawn from chat**: `/acp spawn <agent> --thread here|auto` binds the current topic to a new ACP session; follow-ups route there directly. OpenClaw pins the spawn confirmation in-topic. Requires `channels.telegram.threadBindings.spawnSessions` to remain enabled (default: `true`).
 
     Template context exposes `MessageThreadId` and `IsForum`. DM chats with `message_thread_id` keep DM routing but use thread-aware session keys.
 
diff --git a/docs/concepts/session-tool.md b/docs/concepts/session-tool.md
index e0500ee00..21d5fe198 100644
--- a/docs/concepts/session-tool.md
+++ b/docs/concepts/session-tool.md
@@ -143,6 +143,8 @@ Key options:
 - `sandbox: "require"` to enforce sandboxing on the child.
 - `context: "fork"` for native sub-agents when the child needs the current
   requester transcript; omit it or use `context: "isolated"` for a clean child.
+  Thread-bound native sub-agents default to `context: "fork"` unless
+  `threadBindings.defaultSpawnContext` says otherwise.
 
 Default leaf sub-agents do not get session tools. When
 `maxSpawnDepth >= 2`, depth-1 orchestrator sub-agents additionally receive
diff --git a/docs/gateway/config-agents.md b/docs/gateway/config-agents.md
index 8f9aa8610..6bebcc117 100644
--- a/docs/gateway/config-agents.md
+++ b/docs/gateway/config-agents.md
@@ -1174,7 +1174,6 @@ See [Multi-Agent Sandbox & Tools](/tools/multi-agent-sandbox-tools) for preceden
     },
     resetTriggers: ["/new", "/reset"],
     store: "~/.openclaw/agents/{agentId}/sessions/sessions.json",
-    parentForkMaxTokens: 100000, // skip parent-thread fork above this token count (0 disables)
     maintenance: {
       mode: "warn", // warn | enforce
       pruneAfter: "30d",
@@ -1211,9 +1210,6 @@ See [Multi-Agent Sandbox & Tools](/tools/multi-agent-sandbox-tools) for preceden
 - **`identityLinks`**: map canonical ids to provider-prefixed peers for cross-channel session sharing. Dock commands such as `/dock_discord` use the same map to switch the active session's reply route to another linked channel peer; see [Channel docking](/concepts/channel-docking).
 - **`reset`**: primary reset policy. `daily` resets at `atHour` local time; `idle` resets after `idleMinutes`. When both configured, whichever expires first wins. Daily reset freshness uses the session row's `sessionStartedAt`; idle reset freshness uses `lastInteractionAt`. Background/system-event writes such as heartbeat, cron wakeups, exec notifications, and gateway bookkeeping can update `updatedAt`, but they do not keep daily/idle sessions fresh.
 - **`resetByType`**: per-type overrides (`direct`, `group`, `thread`). Legacy `dm` accepted as alias for `direct`.
-- **`parentForkMaxTokens`**: max parent-session `totalTokens` allowed when creating a forked thread session (default `100000`).
-  - If parent `totalTokens` is above this value, OpenClaw starts a fresh thread session instead of inheriting parent transcript history.
-  - Set `0` to disable this guard and always allow parent forking.
 - **`mainKey`**: legacy field. Runtime always uses `"main"` for the main direct-chat bucket.
 - **`agentToAgent.maxPingPongTurns`**: maximum reply-back turns between agents during agent-to-agent exchanges (integer, range: `0`–`5`). `0` disables ping-pong chaining.
 - **`sendPolicy`**: match by `channel`, `chatType` (`direct|group|channel`, with legacy `dm` alias), `keyPrefix`, or `rawKeyPrefix`. First deny wins.
@@ -1229,6 +1225,8 @@ See [Multi-Agent Sandbox & Tools](/tools/multi-agent-sandbox-tools) for preceden
   - `enabled`: master default switch (providers can override; Discord uses `channels.discord.threadBindings.enabled`)
   - `idleHours`: default inactivity auto-unfocus in hours (`0` disables; providers can override)
   - `maxAgeHours`: default hard max age in hours (`0` disables; providers can override)
+  - `spawnSessions`: default gate for creating thread-bound work sessions from `sessions_spawn` and ACP thread spawns. Defaults to `true` when thread bindings are enabled; providers/accounts can override.
+  - `defaultSpawnContext`: default native subagent context for thread-bound spawns (`"fork"` or `"isolated"`). Defaults to `"fork"`.
 
 </Accordion>
 
diff --git a/docs/gateway/config-channels.md b/docs/gateway/config-channels.md
index fe4644495..66af03250 100644
--- a/docs/gateway/config-channels.md
+++ b/docs/gateway/config-channels.md
@@ -285,7 +285,8 @@ WhatsApp runs through the gateway's web channel (Baileys Web). It starts automat
         enabled: true,
         idleHours: 24,
         maxAgeHours: 0,
-        spawnSubagentSessions: false, // opt-in for sessions_spawn({ thread: true })
+        spawnSessions: true,
+        defaultSpawnContext: "fork",
       },
       voice: {
         enabled: true,
@@ -336,7 +337,8 @@ WhatsApp runs through the gateway's web channel (Baileys Web). It starts automat
   - `enabled`: Discord override for thread-bound session features (`/focus`, `/unfocus`, `/agents`, `/session idle`, `/session max-age`, and bound delivery/routing)
   - `idleHours`: Discord override for inactivity auto-unfocus in hours (`0` disables)
   - `maxAgeHours`: Discord override for hard max age in hours (`0` disables)
-  - `spawnSubagentSessions`: opt-in switch for `sessions_spawn({ thread: true })` auto thread creation/binding
+  - `spawnSessions`: switch for `sessions_spawn({ thread: true })` and ACP thread-spawn auto thread creation/binding (default: `true`)
+  - `defaultSpawnContext`: native subagent context for thread-bound spawns (`"fork"` by default)
 - Top-level `bindings[]` entries with `type: "acp"` configure persistent ACP bindings for channels and threads (use channel/thread id in `match.peer.id`). Field semantics are shared in [ACP Agents](/tools/acp-agents#channel-specific-settings).
 - `channels.discord.ui.components.accentColor` sets the accent color for Discord components v2 containers.
 - `channels.discord.voice` enables Discord voice channel conversations and optional auto-join + LLM + TTS overrides. Text-only Discord configs leave voice off by default; set `channels.discord.voice.enabled=true` to opt in.
diff --git a/docs/help/faq.md b/docs/help/faq.md
index c9db380d7..52419b68f 100644
--- a/docs/help/faq.md
+++ b/docs/help/faq.md
@@ -215,7 +215,7 @@ lives on the [First-run FAQ](/help/faq-first-run).
 
     - Global defaults: `session.threadBindings.enabled`, `session.threadBindings.idleHours`, `session.threadBindings.maxAgeHours`.
     - Discord overrides: `channels.discord.threadBindings.enabled`, `channels.discord.threadBindings.idleHours`, `channels.discord.threadBindings.maxAgeHours`.
-    - Auto-bind on spawn: set `channels.discord.threadBindings.spawnSubagentSessions: true`.
+    - Auto-bind on spawn: `channels.discord.threadBindings.spawnSessions` defaults to `true`; set it to `false` to disable thread-bound session spawns.
 
     Docs: [Sub-agents](/tools/subagents), [Discord](/channels/discord), [Configuration Reference](/gateway/configuration-reference), [Slash commands](/tools/slash-commands).
 
diff --git a/docs/reference/session-management-compaction.md b/docs/reference/session-management-compaction.md
index 32b92e2b3..f6f871239 100644
--- a/docs/reference/session-management-compaction.md
+++ b/docs/reference/session-management-compaction.md
@@ -148,7 +148,7 @@ Rules of thumb:
 - **Daily reset** (default 4:00 AM local time on the gateway host) creates a new `sessionId` on the next message after the reset boundary.
 - **Idle expiry** (`session.reset.idleMinutes` or legacy `session.idleMinutes`) creates a new `sessionId` when a message arrives after the idle window. When daily + idle are both configured, whichever expires first wins.
 - **System events** (heartbeat, cron wakeups, exec notifications, gateway bookkeeping) may mutate the session row but do not extend daily/idle reset freshness. Reset rollover discards queued system-event notices for the previous session before the fresh prompt is built.
-- **Thread parent fork guard** (`session.parentForkMaxTokens`, default `100000`) skips parent transcript forking when the parent session is already too large; the new thread starts fresh. Set `0` to disable.
+- **Parent fork policy** uses PI's active branch when creating a thread or subagent fork. If that branch is too large, OpenClaw starts the child with isolated context instead of failing or inheriting unusable history. The sizing policy is automatic; legacy `session.parentForkMaxTokens` config is removed by `openclaw doctor --fix`.
 
 Implementation detail: the decision happens in `initSessionState()` in `src/auto-reply/reply/session.ts`.
 
diff --git a/docs/tools/acp-agents-setup.md b/docs/tools/acp-agents-setup.md
index 44787262c..317d20b0e 100644
--- a/docs/tools/acp-agents-setup.md
+++ b/docs/tools/acp-agents-setup.md
@@ -109,7 +109,7 @@ Thread binding config is channel-adapter specific. Example for Discord:
     discord: {
       threadBindings: {
         enabled: true,
-        spawnAcpSessions: true,
+        spawnSessions: true,
       },
     },
   },
@@ -118,7 +118,7 @@ Thread binding config is channel-adapter specific. Example for Discord:
 
 If thread-bound ACP spawn does not work, verify the adapter feature flag first:
 
-- Discord: `channels.discord.threadBindings.spawnAcpSessions=true`
+- Discord: `channels.discord.threadBindings.spawnSessions=true`
 
 Current-conversation binds do not require child-thread creation. They require an active conversation context and a channel adapter that exposes ACP conversation bindings.
 
diff --git a/docs/tools/acp-agents.md b/docs/tools/acp-agents.md
index c1ec71ea7..2076dcc09 100644
--- a/docs/tools/acp-agents.md
+++ b/docs/tools/acp-agents.md
@@ -279,7 +279,7 @@ Examples:
   <Accordion title="Binding rules and exclusivity">
     - `--bind here` and `--thread ...` are mutually exclusive.
     - `--bind here` only works on channels that advertise current-conversation binding; OpenClaw returns a clear unsupported message otherwise. Bindings persist across gateway restarts.
-    - On Discord, `spawnAcpSessions` is only required when OpenClaw needs to create a child thread for `--thread auto|here` — not for `--bind here`.
+    - On Discord, `spawnSessions` gates child thread creation for `--thread auto|here` — not `--bind here`.
     - If you spawn to a different ACP agent without `--cwd`, OpenClaw inherits the **target agent's** workspace by default. Missing inherited paths (`ENOENT`/`ENOTDIR`) fall back to the backend default; other access errors (e.g. `EACCES`) surface as spawn errors.
     - Gateway management commands stay local in bound conversations — `/acp ...` commands are handled by OpenClaw even when normal follow-up text routes to the bound ACP session; `/status` and `/unfocus` also stay local whenever command handling is enabled for that surface.
 
@@ -297,9 +297,9 @@ Examples:
 
     - `acp.enabled=true`
     - `acp.dispatch.enabled` is on by default (set `false` to pause automatic ACP thread dispatch; explicit `sessions_spawn({ runtime: "acp" })` calls still work).
-    - Channel-adapter ACP thread-spawn flag enabled (adapter-specific):
-      - Discord: `channels.discord.threadBindings.spawnAcpSessions=true`
-      - Telegram: `channels.telegram.threadBindings.spawnAcpSessions=true`
+    - Channel-adapter thread session spawns enabled (default: `true`):
+      - Discord: `channels.discord.threadBindings.spawnSessions=true`
+      - Telegram: `channels.telegram.threadBindings.spawnSessions=true`
 
     Thread binding support is adapter-specific. If the active channel
     adapter does not support thread bindings, OpenClaw returns a clear
@@ -592,8 +592,8 @@ Two ways to start an ACP session:
 
     - On non-thread binding surfaces, default behavior is effectively `off`.
     - Thread-bound spawn requires channel policy support:
-      - Discord: `channels.discord.threadBindings.spawnAcpSessions=true`
-      - Telegram: `channels.telegram.threadBindings.spawnAcpSessions=true`
+      - Discord: `channels.discord.threadBindings.spawnSessions=true`
+      - Telegram: `channels.telegram.threadBindings.spawnSessions=true`
     - Use `--bind here` when you want to pin the current conversation without creating a child thread.
 
   </Tab>
diff --git a/docs/tools/subagents.md b/docs/tools/subagents.md
index 6c1b45441..d48497b9f 100644
--- a/docs/tools/subagents.md
+++ b/docs/tools/subagents.md
@@ -26,8 +26,10 @@ Primary goals:
 default. For heavy or repetitive tasks, set a cheaper model for sub-agents
 and keep your main agent on a higher-quality model. Configure via
 `agents.defaults.subagents.model` or per-agent overrides. When a child
-genuinely needs the requester's current transcript, the agent can request
-`context: "fork"` on that one spawn.
+    genuinely needs the requester's current transcript, the agent can request
+    `context: "fork"` on that one spawn. Thread-bound subagent sessions default
+    to `context: "fork"` because they branch the current conversation into a
+    follow-up thread.
 </Note>
 
 ## Slash command
@@ -179,7 +181,7 @@ session to confirm the effective tool list.
   `require` rejects spawn unless the target child runtime is sandboxed.
 </ParamField>
 <ParamField path="context" type='"isolated" | "fork"' default="isolated">
-  `fork` branches the requester's current transcript into the child session. Native sub-agents only. Use `fork` only when the child needs the current transcript.
+  `fork` branches the requester's current transcript into the child session. Native sub-agents only. Thread-bound spawns default to `fork`; non-thread spawns default to `isolated`.
 </ParamField>
 
 <Warning>
@@ -203,7 +205,7 @@ persistent thread-bound subagent sessions (`sessions_spawn` with
 `channels.discord.threadBindings.enabled`,
 `channels.discord.threadBindings.idleHours`,
 `channels.discord.threadBindings.maxAgeHours`, and
-`channels.discord.threadBindings.spawnSubagentSessions`.
+`channels.discord.threadBindings.spawnSessions`.
 
 ### Quick flow