diff --git a/docs/release-control/v6/internal/subsystems/ai-runtime.md b/docs/release-control/v6/internal/subsystems/ai-runtime.md
index b2861dcc9..11223231e 100644
--- a/docs/release-control/v6/internal/subsystems/ai-runtime.md
+++ b/docs/release-control/v6/internal/subsystems/ai-runtime.md
@@ -108,7 +108,7 @@ runtime cost control, and shared AI transport surfaces.
 
 ## Completion Obligations
 
-1. Update this contract when canonical AI runtime or transport entry points move
+1. Update this contract when canonical AI runtime or transport entry points move, including transport-level provider request-shape changes such as DeepSeek `tool_choice` coercion
 2. Keep AI runtime and shared API proof routing aligned in `registry.json`
 3. Preserve explicit coverage for chat, Patrol, remediation, and cost-control behavior when AI runtime changes
    Patrol runtime failures are part of that runtime contract: provider, model,
@@ -1625,11 +1625,14 @@ event emission through the same canonical finalizer used for `[DONE]` instead
 of dropping the last chunk or leaving tool calls unfinalized on clean close.
 That same provider-transport boundary owns OpenAI-compatible tool protocol
 adaptation. For direct DeepSeek provider paths, the shared OpenAI-compatible
-client must preserve specific or required `tool_choice` values for current
-DeepSeek V4 tool-capable models and the legacy aliases that currently route to
-that V4 contract. Unknown direct DeepSeek model IDs must still degrade offered
-tool requests to provider-supported auto tool selection so provider errors
-remain model/readiness diagnostics instead of forced-tool protocol noise.
+client must coerce specific or required `tool_choice` values to provider-
+supported auto tool selection for every DeepSeek model ID, including current
+V4 tool-capable models, legacy aliases, and unknown direct DeepSeek IDs.
+DeepSeek's API server-side aliases V4 IDs to `deepseek-reasoner`, which
+rejects forced `tool_choice` with HTTP 400, so coercing to auto for all
+direct DeepSeek paths keeps Patrol functional regardless of how DeepSeek
+routes the requested ID and keeps any provider errors as model or readiness
+diagnostics instead of forced-tool protocol noise.
 Reasoning-backed provider turns that return tool calls with `reasoning_content`
 must preserve that reasoning state on the following tool-result turn when the
 provider requires it, so Assistant and Patrol can complete multi-turn tool use
diff --git a/internal/ai/providers/openai.go b/internal/ai/providers/openai.go
index 98ddf35e9..1ce2d773d 100644
--- a/internal/ai/providers/openai.go
+++ b/internal/ai/providers/openai.go
@@ -12,7 +12,6 @@ import (
 	"strings"
 	"time"
 
-	"github.com/rcourtman/pulse-go-rewrite/internal/config"
 	"github.com/rs/zerolog/log"
 )
 
@@ -182,16 +181,11 @@ func (c *OpenAIClient) shouldSendReasoningContent() bool {
 }
 
 func (c *OpenAIClient) supportsForcedToolChoice(model string) bool {
-	if !c.isDeepSeek() {
-		return true
-	}
-	normalized := normalizeOpenAICompatibleModelName(model)
-	switch {
-	case config.IsDeepSeekV4Model(normalized), config.IsDeepSeekLegacyAliasModel(normalized):
-		return true
-	default:
-		return false
-	}
+	// DeepSeek's API server-side aliases v4-flash/v4-pro to deepseek-reasoner,
+	// which rejects forced tool_choice with HTTP 400. Always coerce to "auto"
+	// for any DeepSeek model so Patrol stays functional regardless of how
+	// DeepSeek routes the requested id.
+	return !c.isDeepSeek()
 }
 
 func (c *OpenAIClient) toolChoiceForModel(model string, choice *ToolChoice) interface{} {
diff --git a/internal/ai/providers/openai_test.go b/internal/ai/providers/openai_test.go
index 288a4ec74..bb1de9bd1 100644
--- a/internal/ai/providers/openai_test.go
+++ b/internal/ai/providers/openai_test.go
@@ -400,17 +400,16 @@ func TestOpenAIClient_ChatStream_ToolChoiceNone_DropsTools(t *testing.T) {
 	assert.True(t, doneCalled)
 }
 
-func TestOpenAIClient_Chat_DeepSeekV4PreservesForcedToolChoice(t *testing.T) {
+func TestOpenAIClient_Chat_DeepSeekCoercesForcedToolChoiceToAuto(t *testing.T) {
+	// DeepSeek's API server-side aliases v4-flash/v4-pro to deepseek-reasoner,
+	// which rejects forced tool_choice with HTTP 400. Pulse coerces any DeepSeek
+	// forced tool_choice to "auto" so Patrol stays functional regardless of how
+	// DeepSeek routes the requested id.
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		var got map[string]interface{}
 		require.NoError(t, json.NewDecoder(r.Body).Decode(&got))
 		assert.Equal(t, "deepseek-v4-flash", got["model"])
-		assert.Equal(t, map[string]interface{}{
-			"type": "function",
-			"function": map[string]interface{}{
-				"name": "ping",
-			},
-		}, got["tool_choice"])
+		assert.Equal(t, "auto", got["tool_choice"])
 		require.Len(t, got["tools"], 1)
 
 		_ = json.NewEncoder(w).Encode(openaiResponse{
@@ -439,12 +438,15 @@ func TestOpenAIClient_Chat_DeepSeekV4PreservesForcedToolChoice(t *testing.T) {
 	require.NoError(t, err)
 }
 
-func TestOpenAIClient_ChatStream_DeepSeekV4PreservesRequiredToolChoice(t *testing.T) {
+func TestOpenAIClient_ChatStream_DeepSeekCoercesAnyToolChoiceToAuto(t *testing.T) {
+	// DeepSeek's API server-side aliases v4-flash/v4-pro to deepseek-reasoner,
+	// which rejects forced tool_choice with HTTP 400. Pulse coerces any DeepSeek
+	// forced tool_choice to "auto" on streaming requests as well.
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		var got map[string]interface{}
 		require.NoError(t, json.NewDecoder(r.Body).Decode(&got))
 		assert.Equal(t, "deepseek-v4-flash", got["model"])
-		assert.Equal(t, "required", got["tool_choice"])
+		assert.Equal(t, "auto", got["tool_choice"])
 		require.Len(t, got["tools"], 1)
 
 		w.Header().Set("Content-Type", "text/event-stream")