adds pause resume flows for streaming calls

AGENTS.md

@@ -245,6 +245,13 @@ ctx.WithValue(key, value)    // Chainable variant
 
 **Gotcha**: `BlockRestrictedWrites()` silently drops writes to reserved keys. This prevents plugins from accidentally overwriting internal state.
 
+**Hard rule — never store stream-sized data in `BifrostContext`.** Context holds small handles only: IDs, durations, booleans, interface pointers. Any per-request state that scales with stream content (chunk buffers, accumulated payloads, replay queues, large per-request slices/maps) must live in a top-level manager keyed by `RequestID`, not in `ctx`. Reference implementations:
+
+- `framework/streaming.Accumulator` — owns a `sync.Map` of per-stream `StreamAccumulator` entries keyed by `RequestID`. Only `BifrostContextKeyAccumulatorID` (the ID string) is stored on the context; the chunk buffers live in the manager. The pause/resume gate (`gate.go`) extends the same per-stream entry with a state machine — again, **no buffer in ctx**.
+- The `Tracer` interface (in ctx as a small pointer) is the access path for plugins/providers to reach managers without putting bulky data on the context itself.
+
+When in doubt: if your new ctx key would hold a slice/map that grows with request content, route the storage through a manager and keep only the ID in ctx.
+
 ---
 
 ## Core Patterns

core/bifrost.go

@@ -4948,7 +4948,7 @@ func (bifrost *Bifrost) tryStreamRequest(ctx *schemas.BifrostContext, req *schem
 					pipeline.FinalizeStreamingPostHookSpans(ctx)
 					bifrost.releasePluginPipeline(pipeline)
 				}()
-				defer close(outputStream)
+				defer providerUtils.CloseStream(ctx, outputStream)
 
 				for streamMsg := range shortCircuit.Stream {
 					if streamMsg == nil {
@@ -4986,9 +4986,9 @@ func (bifrost *Bifrost) tryStreamRequest(ctx *schemas.BifrostContext, req *schem
 					// Guarded send: if the consumer abandons outputStream (client
 					// disconnect, ctx cancel), drain the upstream shortCircuit.Stream
 					// so its producer can exit cleanly instead of blocking on its send.
-					select {
-					case outputStream <- streamResponse:
-					case <-ctx.Done():
+					// GateSendChunk routes through the pause/resume gate when a plugin
+					// has engaged it; otherwise it's a bare ctx-guarded channel send.
+					if !providerUtils.GateSendChunk(ctx, streamResponse, outputStream) {
 						for range shortCircuit.Stream {
 						}
 						return

core/providers/anthropic/anthropic.go

@@ -666,7 +666,7 @@ func HandleAnthropicChatCompletionStreaming(
 	// Large payload streaming passthrough — pipe raw upstream SSE to client
 	if providerUtils.SetupStreamingPassthrough(ctx, resp) {
 		responseChan := make(chan *schemas.BifrostStreamChunk)
-		close(responseChan)
+		providerUtils.CloseStream(ctx, responseChan)
 		return responseChan, nil
 	}
 
@@ -682,7 +682,7 @@ func HandleAnthropicChatCompletionStreaming(
 			} else if ctx.Err() == context.DeadlineExceeded {
 				providerUtils.HandleStreamTimeout(ctx, postHookRunner, responseChan, logger, postHookSpanFinalizer)
 			}
-			close(responseChan)
+			providerUtils.CloseStream(ctx, responseChan)
 		}()
 		defer providerUtils.ReleaseStreamingResponse(resp)
 
@@ -1133,7 +1133,7 @@ func HandleAnthropicResponsesStream(
 	// Large payload streaming passthrough — pipe raw upstream SSE to client
 	if providerUtils.SetupStreamingPassthrough(ctx, resp) {
 		responseChan := make(chan *schemas.BifrostStreamChunk)
-		close(responseChan)
+		providerUtils.CloseStream(ctx, responseChan)
 		return responseChan, nil
 	}
 
@@ -1149,7 +1149,7 @@ func HandleAnthropicResponsesStream(
 			} else if ctx.Err() == context.DeadlineExceeded {
 				providerUtils.HandleStreamTimeout(ctx, postHookRunner, responseChan, logger, postHookSpanFinalizer)
 			}
-			close(responseChan)
+			providerUtils.CloseStream(ctx, responseChan)
 		}()
 		defer providerUtils.ReleaseStreamingResponse(resp)
 		// If body stream is nil, return an error

core/providers/azure/azure.go

@@ -1046,7 +1046,7 @@ func (provider *AzureProvider) SpeechStream(ctx *schemas.BifrostContext, postHoo
 			} else if ctx.Err() == context.DeadlineExceeded {
 				providerUtils.HandleStreamTimeout(ctx, postHookRunner, responseChan, provider.logger, postHookSpanFinalizer)
 			}
-			close(responseChan)
+			providerUtils.CloseStream(ctx, responseChan)
 		}()
 		// Always release response on exit; bodyStream close should prevent indefinite blocking.
 		defer providerUtils.ReleaseStreamingResponse(resp)

core/providers/bedrock/bedrock.go

@@ -914,7 +914,7 @@ func (provider *BedrockProvider) TextCompletionStream(ctx *schemas.BifrostContex
 			} else if ctx.Err() == context.DeadlineExceeded {
 				providerUtils.HandleStreamTimeout(ctx, postHookRunner, responseChan, provider.logger, postHookSpanFinalizer)
 			}
-			close(responseChan)
+			providerUtils.CloseStream(ctx, responseChan)
 		}()
 		defer resp.Body.Close()
 
@@ -1140,7 +1140,7 @@ func (provider *BedrockProvider) ChatCompletionStream(ctx *schemas.BifrostContex
 			} else if ctx.Err() == context.DeadlineExceeded {
 				providerUtils.HandleStreamTimeout(ctx, postHookRunner, responseChan, provider.logger, postHookSpanFinalizer)
 			}
-			close(responseChan)
+			providerUtils.CloseStream(ctx, responseChan)
 		}()
 		defer resp.Body.Close()
 
@@ -1504,7 +1504,7 @@ func (provider *BedrockProvider) ResponsesStream(ctx *schemas.BifrostContext, po
 			} else if ctx.Err() == context.DeadlineExceeded {
 				providerUtils.HandleStreamTimeout(ctx, postHookRunner, responseChan, provider.logger, postHookSpanFinalizer)
 			}
-			close(responseChan)
+			providerUtils.CloseStream(ctx, responseChan)
 		}()
 		// Always release response on exit; bodyStream close should prevent indefinite blocking.
 		defer resp.Body.Close()

core/providers/cohere/cohere.go

@@ -489,7 +489,7 @@ func (provider *CohereProvider) ChatCompletionStream(ctx *schemas.BifrostContext
 	// Large payload streaming passthrough — pipe raw upstream SSE to client
 	if providerUtils.SetupStreamingPassthrough(ctx, resp) {
 		responseChan := make(chan *schemas.BifrostStreamChunk)
-		close(responseChan)
+		providerUtils.CloseStream(ctx, responseChan)
 		return responseChan, nil
 	}
 
@@ -507,7 +507,7 @@ func (provider *CohereProvider) ChatCompletionStream(ctx *schemas.BifrostContext
 			} else if ctx.Err() == context.DeadlineExceeded {
 				providerUtils.HandleStreamTimeout(ctx, postHookRunner, responseChan, provider.logger, postHookSpanFinalizer)
 			}
-			close(responseChan)
+			providerUtils.CloseStream(ctx, responseChan)
 		}()
 		defer providerUtils.ReleaseStreamingResponse(resp)
 		// Decompress gzip-encoded streams transparently (no-op for non-gzip)
@@ -753,7 +753,7 @@ func (provider *CohereProvider) ResponsesStream(ctx *schemas.BifrostContext, pos
 	// Large payload streaming passthrough — pipe raw upstream SSE to client
 	if providerUtils.SetupStreamingPassthrough(ctx, resp) {
 		responseChan := make(chan *schemas.BifrostStreamChunk)
-		close(responseChan)
+		providerUtils.CloseStream(ctx, responseChan)
 		return responseChan, nil
 	}
 
@@ -771,7 +771,7 @@ func (provider *CohereProvider) ResponsesStream(ctx *schemas.BifrostContext, pos
 			} else if ctx.Err() == context.DeadlineExceeded {
 				providerUtils.HandleStreamTimeout(ctx, postHookRunner, responseChan, provider.logger, postHookSpanFinalizer)
 			}
-			close(responseChan)
+			providerUtils.CloseStream(ctx, responseChan)
 		}()
 		defer providerUtils.ReleaseStreamingResponse(resp)
 		// Decompress gzip-encoded streams transparently (no-op for non-gzip)

core/providers/elevenlabs/elevenlabs.go

@@ -390,7 +390,7 @@ func (provider *ElevenlabsProvider) SpeechStream(ctx *schemas.BifrostContext, po
 			} else if ctx.Err() == context.DeadlineExceeded {
 				providerUtils.HandleStreamTimeout(ctx, postHookRunner, responseChan, provider.logger, postHookSpanFinalizer)
 			}
-			close(responseChan)
+			providerUtils.CloseStream(ctx, responseChan)
 		}()
 		defer providerUtils.ReleaseStreamingResponse(resp)
 		// Decompress gzip-encoded streams transparently (no-op for non-gzip)

core/providers/gemini/gemini.go

@@ -448,7 +448,7 @@ func HandleGeminiChatCompletionStream(
 	// Large payload streaming passthrough — pipe raw upstream SSE to client
 	if providerUtils.SetupStreamingPassthrough(ctx, resp) {
 		responseChan := make(chan *schemas.BifrostStreamChunk)
-		close(responseChan)
+		providerUtils.CloseStream(ctx, responseChan)
 		return responseChan, nil
 	}
 
@@ -464,7 +464,7 @@ func HandleGeminiChatCompletionStream(
 			} else if ctx.Err() == context.DeadlineExceeded {
 				providerUtils.HandleStreamTimeout(ctx, postHookRunner, responseChan, logger, postHookSpanFinalizer)
 			}
-			close(responseChan)
+			providerUtils.CloseStream(ctx, responseChan)
 		}()
 		defer providerUtils.ReleaseStreamingResponse(resp)
 
@@ -943,7 +943,7 @@ func HandleGeminiResponsesStream(
 	// Large payload streaming passthrough — pipe raw upstream SSE to client
 	if providerUtils.SetupStreamingPassthrough(ctx, resp) {
 		responseChan := make(chan *schemas.BifrostStreamChunk)
-		close(responseChan)
+		providerUtils.CloseStream(ctx, responseChan)
 		return responseChan, nil
 	}
 
@@ -959,7 +959,7 @@ func HandleGeminiResponsesStream(
 			} else if ctx.Err() == context.DeadlineExceeded {
 				providerUtils.HandleStreamTimeout(ctx, postHookRunner, responseChan, logger, postHookSpanFinalizer)
 			}
-			close(responseChan)
+			providerUtils.CloseStream(ctx, responseChan)
 		}()
 
 		defer providerUtils.ReleaseStreamingResponse(resp)
@@ -1432,7 +1432,7 @@ func (provider *GeminiProvider) SpeechStream(ctx *schemas.BifrostContext, postHo
 	// Large payload streaming passthrough — pipe raw upstream SSE to client
 	if providerUtils.SetupStreamingPassthrough(ctx, resp) {
 		responseChan := make(chan *schemas.BifrostStreamChunk)
-		close(responseChan)
+		providerUtils.CloseStream(ctx, responseChan)
 		return responseChan, nil
 	}
 
@@ -1450,7 +1450,7 @@ func (provider *GeminiProvider) SpeechStream(ctx *schemas.BifrostContext, postHo
 			} else if ctx.Err() == context.DeadlineExceeded {
 				providerUtils.HandleStreamTimeout(ctx, postHookRunner, responseChan, provider.logger, postHookSpanFinalizer)
 			}
-			close(responseChan)
+			providerUtils.CloseStream(ctx, responseChan)
 		}()
 
 		defer providerUtils.ReleaseStreamingResponse(resp)
@@ -1721,7 +1721,7 @@ func (provider *GeminiProvider) TranscriptionStream(ctx *schemas.BifrostContext,
 	// Large payload streaming passthrough — pipe raw upstream SSE to client
 	if providerUtils.SetupStreamingPassthrough(ctx, resp) {
 		responseChan := make(chan *schemas.BifrostStreamChunk)
-		close(responseChan)
+		providerUtils.CloseStream(ctx, responseChan)
 		return responseChan, nil
 	}
 
@@ -1739,7 +1739,7 @@ func (provider *GeminiProvider) TranscriptionStream(ctx *schemas.BifrostContext,
 			} else if ctx.Err() == context.DeadlineExceeded {
 				providerUtils.HandleStreamTimeout(ctx, postHookRunner, responseChan, provider.logger, postHookSpanFinalizer)
 			}
-			close(responseChan)
+			providerUtils.CloseStream(ctx, responseChan)
 		}()
 		defer providerUtils.ReleaseStreamingResponse(resp)
 		// Decompress gzip-encoded streams transparently (no-op for non-gzip)

core/providers/huggingface/huggingface.go

@@ -1092,7 +1092,7 @@ func (provider *HuggingFaceProvider) ImageGenerationStream(ctx *schemas.BifrostC
 	// Large payload streaming passthrough — pipe raw upstream SSE to client
 	if providerUtils.SetupStreamingPassthrough(ctx, resp) {
 		responseChan := make(chan *schemas.BifrostStreamChunk)
-		close(responseChan)
+		providerUtils.CloseStream(ctx, responseChan)
 		return responseChan, nil
 	}
 
@@ -1105,7 +1105,7 @@ func (provider *HuggingFaceProvider) ImageGenerationStream(ctx *schemas.BifrostC
 	go func() {
 		defer providerUtils.EnsureStreamFinalizerCalled(ctx, postHookSpanFinalizer)
 		defer providerUtils.ReleaseStreamingResponse(resp)
-		defer close(responseChan)
+		defer providerUtils.CloseStream(ctx, responseChan)
 
 		if resp.BodyStream() == nil {
 			bifrostErr := providerUtils.NewBifrostOperationError(
@@ -1471,7 +1471,7 @@ func (provider *HuggingFaceProvider) ImageEditStream(ctx *schemas.BifrostContext
 	// Large payload streaming passthrough — pipe raw upstream SSE to client
 	if providerUtils.SetupStreamingPassthrough(ctx, resp) {
 		responseChan := make(chan *schemas.BifrostStreamChunk)
-		close(responseChan)
+		providerUtils.CloseStream(ctx, responseChan)
 		return responseChan, nil
 	}
 
@@ -1484,7 +1484,7 @@ func (provider *HuggingFaceProvider) ImageEditStream(ctx *schemas.BifrostContext
 	go func() {
 		defer providerUtils.EnsureStreamFinalizerCalled(ctx, postHookSpanFinalizer)
 		defer providerUtils.ReleaseStreamingResponse(resp)
-		defer close(responseChan)
+		defer providerUtils.CloseStream(ctx, responseChan)
 
 		if resp.BodyStream() == nil {
 			bifrostErr := providerUtils.NewBifrostOperationError(

core/providers/mistral/mistral.go

@@ -455,7 +455,7 @@ func (provider *MistralProvider) TranscriptionStream(ctx *schemas.BifrostContext
 	// Large payload streaming passthrough — pipe raw upstream SSE to client
 	if providerUtils.SetupStreamingPassthrough(ctx, resp) {
 		responseChan := make(chan *schemas.BifrostStreamChunk)
-		close(responseChan)
+		providerUtils.CloseStream(ctx, responseChan)
 		return responseChan, nil
 	}
 
@@ -472,7 +472,7 @@ func (provider *MistralProvider) TranscriptionStream(ctx *schemas.BifrostContext
 			} else if ctx.Err() == context.DeadlineExceeded {
 				providerUtils.HandleStreamTimeout(ctx, postHookRunner, responseChan, provider.logger, postHookSpanFinalizer)
 			}
-			close(responseChan)
+			providerUtils.CloseStream(ctx, responseChan)
 		}()
 		defer providerUtils.ReleaseStreamingResponse(resp)
 		// Decompress gzip-encoded streams transparently (no-op for non-gzip)