diff --git a/docs/api/async-runtime-mode-label.md b/docs/api/async-runtime-mode-label.md
index 45b2732..b18c50e 100644
--- a/docs/api/async-runtime-mode-label.md
+++ b/docs/api/async-runtime-mode-label.md
@@ -2,8 +2,8 @@
 name: async-runtime-mode-label
 group: api
 category: async
-update-time: 20260512
-description: Convert AsyncRuntimeMode into a stable string label for logs, JSON, and diagnostics.
+update-time: 20260614
+description: Convert AsyncRuntimeMode into its canonical stable string label for logs, JSON, and diagnostics.
 key-word:
     - async
     - runtime
@@ -37,6 +37,7 @@ Detailed rules explaining key parameters and behaviors
 - It keeps mode serialization logic in one place.
 - This helper is used by async runtime JSON helpers.
 - Labels are more stable for telemetry and docs than ad hoc manual matching at call sites.
+- The current canonical labels are exactly `native_worker` for `NativeWorker` and `compatibility` for `Compatibility`.
 
 ### How to Use
 
@@ -67,3 +68,9 @@ e.g.:
 
 - If callers need the whole runtime object rather than a string label, use `async_runtime_state()`.
 
+### Notes
+
+1. Use this helper when mode values should be rendered as stable text instead of manual enum matching.
+
+2. `async_runtime_state_to_json(...)` uses these exact labels when serializing runtime snapshots.
+
diff --git a/docs/api/async-runtime-state-to-json.md b/docs/api/async-runtime-state-to-json.md
index ea6e5f6..dd511bf 100644
--- a/docs/api/async-runtime-state-to-json.md
+++ b/docs/api/async-runtime-state-to-json.md
@@ -2,8 +2,8 @@
 name: async-runtime-state-to-json
 group: api
 category: async
-update-time: 20260512
-description: Convert AsyncRuntimeState into a JSON value for runtime capability and mode diagnostics.
+update-time: 20260614
+description: Convert AsyncRuntimeState into a JSON value for runtime capability and mode diagnostics using the canonical mode labels and snapshot field names.
 key-word:
     - async
     - state
@@ -35,6 +35,7 @@ Detailed rules explaining key parameters and behaviors
 
 - The output includes `mode` and `background_worker`.
 - `mode` is serialized through `async_runtime_mode_label(...)`.
+- The compact serialized shape is `{"mode":"native_worker|compatibility","background_worker":true|false}`.
 - This helper focuses on runtime capabilities rather than queue counters or logger lifecycle flags.
 - The exported JSON is suitable for diagnostics endpoints and startup environment checks.
 
@@ -67,3 +68,9 @@ e.g.:
 
 - If the runtime is in compatibility mode, the helper still serializes normally using the matching mode label.
 
+### Notes
+
+1. The output field names are fixed as `mode` and `background_worker`.
+
+2. The `mode` field always uses the canonical labels from `async_runtime_mode_label(...)`, not enum names like `NativeWorker` or `Compatibility`.
+
diff --git a/docs/api/stringify-async-runtime-state.md b/docs/api/stringify-async-runtime-state.md
index fa6b5fd..d4bf52a 100644
--- a/docs/api/stringify-async-runtime-state.md
+++ b/docs/api/stringify-async-runtime-state.md
@@ -2,8 +2,8 @@
 name: stringify-async-runtime-state
 group: api
 category: async
-update-time: 20260512
-description: Serialize AsyncRuntimeState into compact or pretty JSON text for diagnostics and startup reporting.
+update-time: 20260614
+description: Serialize AsyncRuntimeState into compact or pretty JSON text for diagnostics and startup reporting using the canonical runtime snapshot shape.
 key-word:
     - async
     - state
@@ -40,6 +40,7 @@ Detailed rules explaining key parameters and behaviors
 - `pretty=false` returns compact JSON.
 - `pretty=true` returns indented JSON for human diagnostics.
 - This helper is built on top of `async_runtime_state_to_json(...)`.
+- The compact form matches the tested snapshot shape such as `{"mode":"native_worker","background_worker":true}`.
 - It is well-suited for startup banners, support reports, and target capability logs.
 
 ### How to Use
@@ -71,3 +72,9 @@ e.g.:
 
 - If more complete async logger diagnostics are required, this helper should be replaced with `stringify_async_logger_state(...)`.
 
+### Notes
+
+1. The compact output uses the same canonical `mode` labels as `async_runtime_mode_label(...)`.
+
+2. This helper is the direct text form of the same two-field runtime snapshot exported by `async_runtime_state_to_json(...)`.
+