feat(v1.0.0): implement action prefix stripping in reducers

Breaking Change:
- Reducers with @action_prefix now receive action types with the prefix stripped
- Example: With @action_prefix "counter", handle_action receives "increment"
  instead of "counter.increment"
- Dispatch calls remain unchanged (still use full prefixed names)
- Catch-all reducers (prefix nil/"") receive unchanged action types

Benefits:
- Cleaner reducer code without prefix repetition
- Reducers focus on local action names
- Better separation of concerns
- Consistent with Redux best practices

Implementation:
- Added strip_action_prefix/2 helper function
- Strips prefix before passing to handle_action/handle_async
- Only affects reducers with non-nil/non-empty @action_prefix

Changes:
- lib/phoenix/session_process.ex: Core prefix stripping logic
- examples/02_redux_reducers.exs: Updated 5 action type patterns
- examples/03_async_actions.exs: Updated 5 action type patterns
- test/phoenix/session_process/reducer_integration_test.exs: Updated 3 patterns
- README.md: Updated 2 documentation patterns
- CLAUDE.md: Updated 5 documentation patterns
- CHANGELOG.md: Added breaking change documentation with migration guide

Testing:
- All 148 tests passing
- Examples 01 and 02 verified working
- Example 03 has unrelated Task reply issue (not from this change)

Migration:
1. Remove prefix from action type patterns in handle_action/handle_async
2. Keep dispatch calls unchanged
3. Only affects reducers with explicit @action_prefix

Author: GSMLG-BOT

CHANGELOG.md

@@ -51,6 +51,39 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   - Use the Redux Store API (built into SessionProcess) instead
   - See migration guide: `REDUX_TO_SESSIONPROCESS_MIGRATION.md`
 
+- **Action prefix stripping in reducers**
+  - Reducers with `@action_prefix` now receive action types with the prefix stripped
+  - When a reducer has `@action_prefix "counter"`, `handle_action` receives `"increment"` instead of `"counter.increment"`
+  - Dispatch calls still use full prefixed names (e.g., `dispatch(id, "counter.increment")`)
+  - Catch-all reducers (prefix `nil` or `""`) receive unchanged action types
+  - Migration:
+    ```elixir
+    # Before (v0.x)
+    defmodule CounterReducer do
+      use Phoenix.SessionProcess, :reducer
+      @name :counter
+      @action_prefix "counter"
+
+      def handle_action(%Action{type: "counter.increment"}, state) do
+        %{state | count: state.count + 1}
+      end
+    end
+
+    # After (v1.0.0)
+    defmodule CounterReducer do
+      use Phoenix.SessionProcess, :reducer
+      @name :counter
+      @action_prefix "counter"
+
+      def handle_action(%Action{type: "increment"}, state) do
+        %{state | count: state.count + 1}
+      end
+    end
+
+    # Dispatch calls remain unchanged
+    dispatch(session_id, "counter.increment")
+    ```
+
 ### Added
 
 - **`dispatch_async/3` function for explicit async dispatch**
@@ -72,12 +105,18 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
    - Replace with `@action_prefix`
    - No logic changes required
 
-2. **Update dispatch call sites to handle `:ok` return value**
+2. **Update action type patterns in handle_action/handle_async**
+   - Remove the prefix from action type patterns
+   - Example: `"counter.increment"` becomes `"increment"`
+   - Dispatch calls remain unchanged (still use full prefixed names)
+   - Only affects reducers with non-nil/non-empty `@action_prefix`
+
+3. **Update dispatch call sites to handle `:ok` return value**
    - Replace `{:ok, state} = dispatch(...)` with `:ok = dispatch(...)`
    - Add `get_state(session_id)` calls where you need the updated state
    - Consider: Do you actually need the state? Many dispatches are fire-and-forget
 
-3. **Remove uses of deprecated Redux module**
+4. **Remove uses of deprecated Redux module**
    - If using `Phoenix.SessionProcess.Redux` struct-based API
    - Migrate to Redux Store API (SessionProcess IS the store)
    - See `REDUX_TO_SESSIONPROCESS_MIGRATION.md` for detailed migration

CLAUDE.md

@@ -323,10 +323,10 @@ defmodule MyApp.CounterReducer do
     alias Phoenix.SessionProcess.Action
 
     case action do
-      %Action{type: "counter.increment"} ->
+      %Action{type: "increment"} ->
         %{state | count: state.count + 1}
 
-      %Action{type: "counter.set", payload: value} ->
+      %Action{type: "set", payload: value} ->
         %{state | count: value}
 
       _ ->
@@ -349,10 +349,10 @@ defmodule MyApp.UserReducer do
     alias Phoenix.SessionProcess.Action
 
     case action do
-      %Action{type: "user.set", payload: user} ->
+      %Action{type: "set", payload: user} ->
         %{state | current_user: user}
 
-      %Action{type: "user.update_preferences", payload: prefs} ->
+      %Action{type: "update_preferences", payload: prefs} ->
         %{state | preferences: Map.merge(state.preferences, prefs)}
 
       _ ->
@@ -365,7 +365,7 @@ defmodule MyApp.UserReducer do
     alias Phoenix.SessionProcess.Action
 
     case action do
-      %Action{type: "user.fetch", payload: user_id} ->
+      %Action{type: "fetch", payload: user_id} ->
         task = Task.async(fn ->
           user = MyApp.Users.get(user_id)
           # dispatch signature: dispatch(type, payload \\ nil, meta \\ [])

README.md

@@ -163,10 +163,10 @@ defmodule MyApp.CounterReducer do
     alias Phoenix.SessionProcess.Action
 
     case action do
-      %Action{type: "counter.increment"} ->
+      %Action{type: "increment"} ->
         %{state | count: state.count + 1}
 
-      %Action{type: "counter.set", payload: value} ->
+      %Action{type: "set", payload: value} ->
         %{state | count: value}
 
       _ ->

examples/02_redux_reducers.exs

@@ -24,13 +24,13 @@ defmodule CounterReducer do
     alias Phoenix.SessionProcess.Action
 
     case action do
-      %Action{type: "counter.increment"} ->
+      %Action{type: "increment"} ->
         %{state | count: state.count + 1}
 
-      %Action{type: "counter.decrement"} ->
+      %Action{type: "decrement"} ->
         %{state | count: state.count - 1}
 
-      %Action{type: "counter.set", payload: value} ->
+      %Action{type: "set", payload: value} ->
         %{state | count: value}
 
       _ ->
@@ -54,10 +54,10 @@ defmodule UserReducer do
     alias Phoenix.SessionProcess.Action
 
     case action do
-      %Action{type: "user.login", payload: user} ->
+      %Action{type: "login", payload: user} ->
         %{state | current_user: user, logged_in: true}
 
-      %Action{type: "user.logout"} ->
+      %Action{type: "logout"} ->
         %{state | current_user: nil, logged_in: false}
 
       _ ->

examples/03_async_actions.exs

@@ -23,16 +23,16 @@ defmodule AsyncReducer do
     alias Phoenix.SessionProcess.Action
 
     case action do
-      %Action{type: "data.loading"} ->
+      %Action{type: "loading"} ->
         %{state | loading: true, error: nil}
 
-      %Action{type: "data.loaded", payload: items} ->
+      %Action{type: "loaded", payload: items} ->
         %{state | items: items, loading: false}
 
-      %Action{type: "data.error", payload: error} ->
+      %Action{type: "error", payload: error} ->
         %{state | error: error, loading: false}
 
-      %Action{type: "data.clear"} ->
+      %Action{type: "clear"} ->
         %{state | items: [], loading: false, error: nil}
 
       _ ->
@@ -45,7 +45,7 @@ defmodule AsyncReducer do
     alias Phoenix.SessionProcess.Action
 
     case action do
-      %Action{type: "data.fetch", payload: delay_ms} ->
+      %Action{type: "fetch", payload: delay_ms} ->
         # Start async task
         task =
           Task.async(fn ->

lib/phoenix/session_process.ex

@@ -1520,13 +1520,34 @@ defmodule Phoenix.SessionProcess do
         Map.put(state, slice_key, slice_initial_state)
       end
 
+      # Strip action prefix before passing to reducer if reducer has a prefix
+      defp strip_action_prefix(action, reducer_prefix) do
+        if reducer_prefix && reducer_prefix != "" do
+          case String.split(action.type, ".", parts: 2) do
+            [^reducer_prefix, local_type] ->
+              %{action | type: local_type}
+
+            _ ->
+              # Prefix doesn't match, keep as-is
+              action
+          end
+        else
+          # No prefix or catch-all reducer, pass unchanged
+          action
+        end
+      end
+
       # credo:disable-for-lines:60 Credo.Check.Refactor.Nesting
       defp apply_combined_reducer(module, action, slice_key, app_state, internal_state) do
         alias Phoenix.SessionProcess.ActionRateLimiter
 
         # Get the state slice for this reducer
         slice_state = Map.get(app_state, slice_key, %{})
 
+        # Get reducer's action prefix and strip it from action type
+        reducer_prefix = module.__reducer_action_prefix__()
+        local_action = strip_action_prefix(action, reducer_prefix)
+
         # Check throttle first
         if ActionRateLimiter.should_throttle?(module, action, internal_state) do
           # Skip action due to throttle
@@ -1551,7 +1572,8 @@ defmodule Phoenix.SessionProcess do
                 dispatch_fn = &__async_dispatch__(session_pid, &1, &2, &3)
 
                 # handle_async returns cancel function, not state
-                cancel_fn = module.handle_async(action, dispatch_fn, slice_state)
+                # Pass local_action with stripped prefix
+                cancel_fn = module.handle_async(local_action, dispatch_fn, slice_state)
 
                 # Store cancel function in internal state if action has cancel_ref
                 new_internal_with_cancel =
@@ -1569,7 +1591,8 @@ defmodule Phoenix.SessionProcess do
                 {slice_state, new_internal_with_cancel}
               else
                 # Synchronous action updates state
-                new_state = module.handle_action(action, slice_state)
+                # Pass local_action with stripped prefix
+                new_state = module.handle_action(local_action, slice_state)
                 {new_state, internal_state}
               end
 

test/phoenix/session_process/reducer_integration_test.exs

@@ -20,10 +20,6 @@ defmodule Phoenix.SessionProcess.ReducerIntegrationTest do
       Map.update(state, :fetch_count, 1, &(&1 + 1))
     end
 
-    def handle_action(%Action{type: "user.fetch-users"}, state) do
-      Map.update(state, :fetch_count, 1, &(&1 + 1))
-    end
-
     @debounce {"search-users", "50ms"}
     def handle_action(%Action{type: "search-users", payload: query}, state) do
       Map.put(state, :search_query, query)
@@ -56,11 +52,6 @@ defmodule Phoenix.SessionProcess.ReducerIntegrationTest do
       Map.put(state, :items, [])
     end
 
-    # Also match with prefix for routing tests
-    def handle_action(%Action{type: "cart.clear-cart"}, state) do
-      Map.put(state, :items, [])
-    end
-
     def handle_action(_action, state), do: state
   end
 
@@ -1172,12 +1163,14 @@ defmodule Phoenix.SessionProcess.ReducerIntegrationTest do
       session_id = "routing_custom_prefix_#{:rand.uniform(1_000_000)}"
       {:ok, _pid} = SessionProcess.start(session_id, CustomPrefixSession)
 
-      # Action with "ship.calculate" should route to ShippingReducer
-      SessionProcess.dispatch(session_id, "ship.calculate-shipping", payload: "123 Main St")
+      # Action with "ship.calculate-shipping" should route to ShippingReducer
+      # After prefix stripping, becomes "calculate-shipping" which matches the handler
+      SessionProcess.dispatch(session_id, "ship.calculate-shipping", "123 Main St")
 
       state = SessionProcess.get_state(session_id)
-      # ShippingReducer doesn't handle this action, but it was routed correctly
-      assert state.shipping.address == nil
+      # ShippingReducer now handles this action with stripped prefix
+      assert state.shipping.address == "123 Main St"
+      assert state.shipping.cost == 10
 
       SessionProcess.terminate(session_id)
     end