feat: expose transaction activity boundary

README.md

@@ -174,7 +174,7 @@ cycles instead of spinning.
 | Core inspection and debug | `tp-debug-*`, `tp-intervals`, `tp-intervals-map`, `tp-plist`, `tp-text-snapshot`, `tp-empty-p` |
 | Property policy and declarations | `tp-define-property-policy`, `tp-register-text-property`, `tp-text-declarations`, `tp-computed`, `tp-resolve-value`, `tp-merge-declarations`, `tp-define-style`, `tp-style-declarations` |
 | Static recipes | `define-tp`/`tp-define-layer`, `define-tps`/`define-tp-group`/`tp-define-group`, layer/group queries, undefine/reset/describe |
-| Signals and bindings | signal create/read/peek/set/dispose, binding install/read/dispose, `tp-variable-signal`, `tp-with-transaction`, `tp-transaction-participate`, counters/reset |
+| Signals and bindings | signal create/read/peek/set/dispose, binding install/read/dispose, `tp-variable-signal`, `tp-with-transaction`, `tp-transaction-participate`, read-only `tp-transaction-active-p`, counters/reset |
 | Objects and plans | plan/result constructors, `tp-object-ensure`, retain/reuse, fragment/content-range attachment, resolve, mounted/mounts |
 | Host ranges | `tp-range-anchor-create`, `tp-range-anchor-live-p`, `tp-object-attach-range`, `tp-range-rebase` |
 | Surfaces | mount/update/scoped update, materialize, live/revision/client-state, at-point, report/report-summary/inspect, unmount |

README_CN.md

@@ -171,7 +171,7 @@ effect 的 input/version tuple，重复或超过图规模上限时停止循环
 | Core inspection 与 debug | `tp-debug-*`、`tp-intervals`、`tp-intervals-map`、`tp-plist`、`tp-text-snapshot`、`tp-empty-p` |
 | Property policy 与 declaration | `tp-define-property-policy`、`tp-register-text-property`、`tp-text-declarations`、`tp-computed`、`tp-resolve-value`、`tp-merge-declarations`、`tp-define-style`、`tp-style-declarations` |
 | 静态 recipe | `define-tp`/`tp-define-layer`、`define-tps`/`define-tp-group`/`tp-define-group`、layer/group 查询、undefine/reset/describe |
-| Signal 与 binding | signal create/read/peek/set/dispose、binding install/read/dispose、`tp-variable-signal`、`tp-with-transaction`、`tp-transaction-participate`、counter/reset |
+| Signal 与 binding | signal create/read/peek/set/dispose、binding install/read/dispose、`tp-variable-signal`、`tp-with-transaction`、`tp-transaction-participate`、只读 `tp-transaction-active-p`、counter/reset |
 | Object 与 plan | plan/result constructor、`tp-object-ensure`、retain/reuse、fragment/content-range attach、resolve、mounted/mounts |
 | Host range | `tp-range-anchor-create`、`tp-range-anchor-live-p`、`tp-object-attach-range`、`tp-range-rebase` |
 | Surface | mount/update/scoped update、materialize、live/revision/client-state、at-point、report/report-summary/inspect、unmount |

docs/API-REFERENCE.md

@@ -231,6 +231,8 @@ tp-binding-dispose 释放单个 binding。
  (lambda () (my-publish))
  (lambda () (my-rollback)))
 
+(tp-transaction-active-p)
+
 (tp-variable-signal 'my-variable)
 (tp-variable-signal 'my-buffer-variable some-buffer)
 (tp-reactive-counters)
@@ -244,6 +246,11 @@ publish 在 surface publication 后、source commit 前运行，失败时按逆
 rollback。tp-variable-signal 用 Emacs variable watcher 适配全局或指定
 Buffer 的变量，不是旧的 $variable API。
 
+tp-transaction-active-p 是只读边界查询：只在当前 dynamic extent 已进入
+或加入 TP transaction 时返回严格的 t，否则返回 nil。它不暴露 transaction
+对象、participant 或内部状态，调用方只能用它在 mutation 前拒绝不支持的
+嵌套事务边界。
+
 ETAF registers one opaque participant for its immutable generation and Ebox
 client state. Its publish is paired with rollback across TP final accept; the
 ETAF runtime separately records effect input/version tuples and reports a

tests/tp-binding-tests.el

@@ -160,6 +160,15 @@
       (should (= calls 2))
       (should (= (plist-get (tp-reactive-counters) :recomputed) 1)))))
 
+(ert-deftest tp-binding-test-public-transaction-state-follows-dynamic-extent ()
+  "The public transaction predicate is true only inside joined transactions."
+  (should-not (tp-transaction-active-p))
+  (tp-with-transaction
+    (should (tp-transaction-active-p))
+    (tp-with-transaction
+      (should (tp-transaction-active-p))))
+  (should-not (tp-transaction-active-p)))
+
 (ert-deftest tp-binding-test-transaction-commits-signals-in-first-touch-order ()
   "Touched signals commit once in first-touch order, including net reverts."
   (tp-binding-test--isolated

tp-reactive.el

@@ -68,6 +68,11 @@
         :subscription-added 0 :subscription-removed 0))
 
 (defvar tp--transaction-active nil)
+
+;;;###autoload
+(defun tp-transaction-active-p ()
+  "Return non-nil while the current dynamic extent is in a TP transaction."
+  (and tp--transaction-active t))
 (defvar tp--transaction-signal-values nil)
 (defvar tp--transaction-signals nil)
 (defvar tp--transaction-dirty-set nil)