Stop relying on previous_response_id for tool-call continuation

Real-world failure: "LLM returned 400 Bad Request: ... No tool call
found for function call output with call_id ...". The planning loop's
continuation request set previous_response_id and sent only the new
function_call_output items, trusting the provider to remember the
matching function_call from the prior turn server-side. MindsHub (and
presumably other OpenAI-compatible proxies that don't persist Responses
API state) doesn't honor that, so the call_id was unrecognized.

plan() now tracks its own transcript (the original task message plus
every function_call/function_call_output pair) and resends it in full
on each round instead of depending on server-side history. Drops the
now-unused previous_response_id field.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

Author: torrmal

internal/agent/agent.go

@@ -34,6 +34,11 @@ type toolArguments struct {
 	Query string   `json:"query"`
 }
 
+type inputMessage struct {
+	Role    string `json:"role"`
+	Content string `json:"content"`
+}
+
 type Runner struct {
 	client     *Client
 	repository *repo.Repository
@@ -127,16 +132,28 @@ func (runner *Runner) route(ctx context.Context, task string) (routeDecision, er
 	return decision, nil
 }
 
+// plan drives the tool-calling loop by resending the full conversation
+// transcript on every round rather than relying on previous_response_id.
+// Not every OpenAI-compatible provider actually persists server-side
+// response state, and one that doesn't will reject a function_call_output
+// referencing a call_id it never stored, so the transcript is tracked here
+// instead.
 func (runner *Runner) plan(ctx context.Context, task, repoMap string) (Plan, string, error) {
-	request := responseRequest{
-		Instructions: planningInstructions,
-		Input:        fmt.Sprintf("TASK:\n%s\n\nREPOSITORY MAP:\n%s", task, repoMap),
-		Tools:        repositoryTools(),
-		ToolChoice:   "auto",
-		Text:         strictSchema("implementation_plan", planSchema()),
-	}
+	taskText := fmt.Sprintf("TASK:\n%s\n\nREPOSITORY MAP:\n%s", task, repoMap)
+	var transcript []any
 	var collected strings.Builder
 	for round := 0; round < maxToolRounds; round++ {
+		var input any = taskText
+		if transcript != nil {
+			input = transcript
+		}
+		request := responseRequest{
+			Instructions: planningInstructions,
+			Input:        input,
+			Tools:        repositoryTools(),
+			ToolChoice:   "auto",
+			Text:         strictSchema("implementation_plan", planSchema()),
+		}
 		callCtx, cancel := context.WithTimeout(ctx, 2*time.Minute)
 		response, err := runner.client.create(callCtx, request)
 		cancel()
@@ -155,19 +172,14 @@ func (runner *Runner) plan(ctx context.Context, task, repoMap string) (Plan, str
 			}
 			return plan, collected.String(), nil
 		}
-		outputs := make([]toolOutput, 0, len(calls))
+		if transcript == nil {
+			transcript = []any{inputMessage{Role: "user", Content: taskText}}
+		}
 		for _, call := range calls {
 			output := runner.runTool(ctx, call)
 			fmt.Fprintf(&collected, "\nTOOL %s:\n%s\n", call.Name, output)
-			outputs = append(outputs, toolOutput{Type: "function_call_output", CallID: call.CallID, Output: output})
-		}
-		request = responseRequest{
-			Instructions:       planningInstructions,
-			PreviousResponseID: response.ID,
-			Input:              outputs,
-			Tools:              repositoryTools(),
-			ToolChoice:         "auto",
-			Text:               strictSchema("implementation_plan", planSchema()),
+			transcript = append(transcript, call)
+			transcript = append(transcript, toolOutput{Type: "function_call_output", CallID: call.CallID, Output: output})
 		}
 	}
 	return Plan{}, "", fmt.Errorf("the model exceeded %d repository tool rounds", maxToolRounds)

internal/agent/agent_test.go

@@ -30,8 +30,25 @@ func TestRunnerToolPlanPatchApply(t *testing.T) {
 		case 2:
 			fmt.Fprint(writer, `{"id":"resp_1","output":[{"type":"function_call","name":"read_files","call_id":"call_1","arguments":"{\"paths\":[\"hello.txt\"]}"}]}`)
 		case 3:
-			if body["previous_response_id"] != "resp_1" {
-				t.Fatalf("previous_response_id = %v", body["previous_response_id"])
+			// The continuation must resend the full transcript itself
+			// rather than lean on previous_response_id: not every
+			// OpenAI-compatible provider persists server-side response
+			// state, and one that doesn't rejects an orphaned
+			// function_call_output.
+			if _, present := body["previous_response_id"]; present {
+				t.Fatalf("previous_response_id must not be sent: %v", body["previous_response_id"])
+			}
+			input, ok := body["input"].([]any)
+			if !ok || len(input) != 3 {
+				t.Fatalf("input = %#v, want a 3-item transcript", body["input"])
+			}
+			call, ok := input[1].(map[string]any)
+			if !ok || call["type"] != "function_call" || call["call_id"] != "call_1" {
+				t.Fatalf("input[1] = %#v, want the echoed function_call", input[1])
+			}
+			output, ok := input[2].(map[string]any)
+			if !ok || output["type"] != "function_call_output" || output["call_id"] != "call_1" {
+				t.Fatalf("input[2] = %#v, want the matching function_call_output", input[2])
 			}
 			fmt.Fprint(writer, `{"id":"resp_2","output":[{"type":"message","content":[{"type":"output_text","text":"{\"summary\":\"Update greeting\",\"files_to_modify\":[\"hello.txt\"],\"context_files\":[],\"steps\":[\"Replace greeting\"]}"}]}]}`)
 		case 4:

internal/agent/client.go

@@ -20,13 +20,12 @@ type Client struct {
 }
 
 type responseRequest struct {
-	Model              string         `json:"model"`
-	Instructions       string         `json:"instructions,omitempty"`
-	Input              any            `json:"input"`
-	PreviousResponseID string         `json:"previous_response_id,omitempty"`
-	Tools              []functionTool `json:"tools,omitempty"`
-	ToolChoice         string         `json:"tool_choice,omitempty"`
-	Text               *textConfig    `json:"text,omitempty"`
+	Model        string         `json:"model"`
+	Instructions string         `json:"instructions,omitempty"`
+	Input        any            `json:"input"`
+	Tools        []functionTool `json:"tools,omitempty"`
+	ToolChoice   string         `json:"tool_choice,omitempty"`
+	Text         *textConfig    `json:"text,omitempty"`
 }
 
 type functionTool struct {