fix(llm): strip inline <think> reasoning from Dahl/MiniMax streams; dedupe identical parallel tool calls; hermetic config tests

internal/agent/agent.go

@@ -178,11 +178,20 @@ func (a *Agent) Run(parent context.Context, sessionID, userText string, emit fun
 		if len(resp.ToolCalls) == 0 {
 			return resp.Content, nil
 		}
+		// Some models (seen with GLM/DeepSeek on Dahl) emit the same call several times in
+		// parallel; identical name+arguments run once and share the result.
+		seen := map[string]string{}
 		for _, tc := range resp.ToolCalls {
 			emit(Event{Type: "tool_call", Tool: tc.Name, Args: tc.Arguments, CallID: tc.ID})
-			out := "error: cancelled by user"
-			if !cancelled() {
+			key := tc.Name + "\x00" + tc.Arguments
+			out, dup := seen[key]
+			switch {
+			case dup:
+			case cancelled():
+				out = "error: cancelled by user"
+			default:
 				out = a.Tools.Call(ctx, tc.Name, tc.Arguments)
+				seen[key] = out
 			}
 			emit(Event{Type: "tool_result", Tool: tc.Name, Text: clip(out, 2000), CallID: tc.ID})
 			// Every tool call gets a result so the history stays valid for the provider.

internal/agent/agent_test.go

@@ -206,3 +206,29 @@ func TestSummarizeNowManual(t *testing.T) {
 		t.Fatalf("%v %v", sm, err)
 	}
 }
+
+func TestDuplicateToolCallsRunOnce(t *testing.T) {
+	st := newStore(t)
+	ss, _ := st.CreateSession(context.Background(), "")
+	n := 0
+	now := func() time.Time { n++; return time.Date(2026, 10, 25, 6, 0, 0, 0, time.UTC) }
+	dup := []llm.ToolCall{{ID: "a", Name: "time_now", Arguments: `{"timezone":"UTC"}`}, {ID: "b", Name: "time_now", Arguments: `{"timezone":"UTC"}`}, {ID: "c", Name: "time_now", Arguments: `{}`}}
+	p := &scripted{resps: []llm.Response{{ToolCalls: dup}, {Content: "ok"}}}
+	a := &Agent{LLM: p, Store: st, Tools: tools.NewRegistry(tools.TimeNow{Now: now}), MaxIterations: 3}
+	if _, err := a.Run(context.Background(), ss.ID, "zeit?", nil); err != nil {
+		t.Fatal(err)
+	}
+	if n != 2 {
+		t.Fatalf("tool executed %d times, want 2", n)
+	}
+	msgs, _ := st.Messages(context.Background(), ss.ID, 0)
+	tools := 0
+	for _, m := range msgs {
+		if m.Role == llm.RoleTool {
+			tools++
+		}
+	}
+	if tools != 3 {
+		t.Fatalf("every call id needs a result, got %d", tools)
+	}
+}

internal/config/presets_test.go

@@ -7,6 +7,7 @@ import (
 )
 
 func load(t *testing.T, yaml string) (Config, error) {
+	t.Helper()
 	t.Helper()
 	p := filepath.Join(t.TempDir(), "c.yaml")
 	os.WriteFile(p, []byte("auth_token: aaaaaaaaaaaaaaaaaaaa\n"+yaml), 0o600)
@@ -74,3 +75,13 @@ func TestAllPresetsComplete(t *testing.T) {
 		}
 	}
 }
+
+// TestMain keeps tests hermetic when the developer shell has BYTECLAW_* or provider keys set.
+func TestMain(m *testing.M) {
+	for _, k := range []string{"BYTECLAW_LISTEN", "BYTECLAW_DATA_DIR", "BYTECLAW_WORKSPACE", "BYTECLAW_LLM_PROVIDER",
+		"BYTECLAW_LLM_BASE_URL", "BYTECLAW_LLM_API_KEY", "BYTECLAW_LLM_MODEL", "BYTECLAW_ALLOWED_ORIGINS", "BYTECLAW_AUTH_TOKEN",
+		"OPENAI_API_KEY", "OPENROUTER_API_KEY", "DAHL_API_KEY", "GONKAROUTER_API_KEY"} {
+		os.Unsetenv(k)
+	}
+	os.Exit(m.Run())
+}

internal/llm/openai.go

@@ -131,6 +131,7 @@ type partialCall struct {
 func parseStream(r io.Reader, onDelta DeltaFunc) (Response, error) {
 	var out Response
 	var text strings.Builder
+	var tf thinkFilter
 	calls := map[int]*partialCall{}
 	sc := bufio.NewScanner(r)
 	sc.Buffer(make([]byte, 64*1024), 4<<20)
@@ -152,9 +153,11 @@ func parseStream(r io.Reader, onDelta DeltaFunc) (Response, error) {
 		}
 		for _, c := range ch.Choices {
 			if c.Delta.Content != "" {
-				text.WriteString(c.Delta.Content)
+				if v := tf.push(c.Delta.Content); v != "" {
+					text.WriteString(v)
 					if onDelta != nil {
-					onDelta(c.Delta.Content)
+						onDelta(v)
+					}
 				}
 			}
 			for i, tc := range c.Delta.ToolCalls {
@@ -183,6 +186,12 @@ func parseStream(r io.Reader, onDelta DeltaFunc) (Response, error) {
 	if err := sc.Err(); err != nil {
 		return out, fmt.Errorf("read stream: %w", err)
 	}
+	if v := tf.finish(); v != "" {
+		text.WriteString(v)
+		if onDelta != nil {
+			onDelta(v)
+		}
+	}
 	out.Content = text.String()
 	idxs := make([]int, 0, len(calls))
 	for i := range calls {

internal/llm/think.go

@@ -0,0 +1,129 @@
+package llm
+
+import "strings"
+
+// thinkFilter removes inline reasoning blocks ("<think>…</think>") that some
+// OpenAI-compatible backends (e.g. MiniMax-M2.x on vLLM, seen on Dahl) put into
+// the normal content stream instead of a separate reasoning field. Tags may be
+// split across chunks. Text inside a block is never streamed to the user.
+type thinkFilter struct {
+	pending string // undecided tail that may be the start of a tag
+	inThink bool
+	think   strings.Builder // reasoning text of the current (unclosed) block
+	out     strings.Builder // visible content
+	sawOpen bool
+}
+
+const (
+	openTag  = "<think>"
+	closeTag = "</think>"
+	gap      = "\n\n\n"
+)
+
+// push consumes a chunk and returns the text that may be shown now.
+func (f *thinkFilter) push(s string) string {
+	buf := f.pending + s
+	f.pending = ""
+	var vis strings.Builder
+	for buf != "" {
+		tag := openTag
+		if f.inThink {
+			tag = closeTag
+		}
+		i, n := strings.Index(buf, tag), len(tag)
+		// Dahl/vLLM sometimes swallows "</think>" and leaves only a "\n\n\n" gap;
+		// treat that gap as the end of the block so the answer still streams live.
+		if f.inThink {
+			if j := strings.Index(buf, gap); j >= 0 && (i < 0 || j < i) {
+				i, n = j, len(gap)
+			}
+		}
+		if i >= 0 {
+			f.emit(&vis, buf[:i])
+			buf = buf[i+n:]
+			if f.inThink {
+				f.think.Reset()
+			} else {
+				f.sawOpen = true
+			}
+			f.inThink = !f.inThink
+			continue
+		}
+		// a stray closing tag outside a block is dropped
+		if !f.inThink {
+			if i := strings.Index(buf, closeTag); i >= 0 {
+				f.emit(&vis, buf[:i])
+				buf = buf[i+len(closeTag):]
+				continue
+			}
+		}
+		keep := partialSuffix(buf, tag)
+		if f.inThink {
+			if k := partialSuffix(buf, gap); k > keep {
+				keep = k
+			}
+		} else {
+			if k := partialSuffix(buf, closeTag); k > keep {
+				keep = k
+			}
+		}
+		f.emit(&vis, buf[:len(buf)-keep])
+		f.pending = buf[len(buf)-keep:]
+		buf = ""
+	}
+	return vis.String()
+}
+
+func (f *thinkFilter) emit(vis *strings.Builder, s string) {
+	if s == "" {
+		return
+	}
+	if f.inThink {
+		f.think.WriteString(s)
+		return
+	}
+	// drop whitespace directly after a closed block at the start of the answer
+	if f.out.Len() == 0 {
+		s = strings.TrimLeft(s, " \n\r\t")
+		if s == "" {
+			return
+		}
+	}
+	f.out.WriteString(s)
+	vis.WriteString(s)
+}
+
+// finish flushes the remainder. If a block was never closed (observed when the
+// backend swallows "</think>"), the answer is recovered from the text after the
+// first blank-line gap so the user does not end up with nothing.
+func (f *thinkFilter) finish() string {
+	var vis strings.Builder
+	if f.pending != "" {
+		p := f.pending
+		f.pending = ""
+		f.emit(&vis, p)
+	}
+	if f.inThink {
+		t := f.think.String()
+		f.inThink = false
+		f.think.Reset()
+		ans := ""
+		if i := strings.Index(t, "\n\n\n"); i >= 0 {
+			ans = t[i:]
+		} else if f.out.Len() == 0 {
+			ans = t // better a visible reasoning than an empty reply
+		}
+		f.emit(&vis, strings.TrimSpace(ans))
+	}
+	return vis.String()
+}
+
+// partialSuffix returns the length of the longest suffix of s that is a proper prefix of tag.
+func partialSuffix(s, tag string) int {
+	for n := len(tag) - 1; n > 0; n-- {
+		if len(s) >= n && strings.HasSuffix(s, tag[:n]) {
+			return n
+		}
+	}
+	return 0
+}

internal/llm/think_test.go

@@ -0,0 +1,75 @@
+package llm
+
+import (
+	"strings"
+	"testing"
+)
+
+func run(chunks ...string) (string, string) {
+	var f thinkFilter
+	var streamed strings.Builder
+	for _, c := range chunks {
+		streamed.WriteString(f.push(c))
+	}
+	streamed.WriteString(f.finish())
+	return streamed.String(), f.out.String()
+}
+
+func TestThinkFilter(t *testing.T) {
+	cases := []struct {
+		name   string
+		chunks []string
+		want   string
+	}{
+		{"plain", []string{"Hallo ", "Welt"}, "Hallo Welt"},
+		{"block", []string{"<think>reasoning\n</think>\n\nHallo!"}, "Hallo!"},
+		{"split tags", []string{"<th", "ink>abc</th", "ink>", "\n\nHal", "lo"}, "Hallo"},
+		{"char by char", strings.Split("<think>x</think>Ja", ""), "Ja"},
+		{"stray close", []string{"Hallo!</think>\n\nHallo!"}, "Hallo!\n\nHallo!"},
+		{"unclosed with gap (Dahl)", []string{"<think>The user asks.\n\n\nHallo! Wie geht's?"}, "Hallo! Wie geht's?"},
+		{"gap streams live", []string{"<think>a\n", "\n", "\nAntw", "ort"}, "Antwort"},
+		{"gap outside block kept", []string{"A\n\n\nB"}, "A\n\n\nB"},
+		{"unclosed no gap", []string{"<think>nur Gedanken"}, "nur Gedanken"},
+		{"lt not a tag", []string{"a <b> c <", "3"}, "a <b> c <3"},
+		{"trailing partial", []string{"x <thi"}, "x <thi"},
+	}
+	for _, c := range cases {
+		streamed, out := run(c.chunks...)
+		if streamed != c.want || out != c.want {
+			t.Errorf("%s: streamed=%q out=%q want %q", c.name, streamed, out, c.want)
+		}
+	}
+}
+
+func TestParseStreamStripsThink(t *testing.T) {
+	sse := `data: {"choices":[{"delta":{"content":"","role":"assistant"}}]}
+
+data: {"choices":[{"delta":{"reasoning":"hidden"}}]}
+
+data: {"choices":[{"delta":{"content":"<think>The user"}}]}
+
+data: {"choices":[{"delta":{"content":" greets.\n</thi"}}]}
+
+data: {"choices":[{"delta":{"content":"nk>\n\nHallo!"}}]}
+
+data: {"choices":[{"delta":{},"finish_reason":"stop"}]}
+
+data: [DONE]
+`
+	var deltas []string
+	resp, err := parseStream(strings.NewReader(sse), func(s string) { deltas = append(deltas, s) })
+	if err != nil || resp.Content != "Hallo!" || strings.Join(deltas, "") != "Hallo!" {
+		t.Fatalf("%q %v %v", resp.Content, deltas, err)
+	}
+}
+
+// The answer after a swallowed </think> must be streamed incrementally, not only at the end.
+func TestThinkGapStreamsIncrementally(t *testing.T) {
+	var f thinkFilter
+	if v := f.push("<think>Überlegung\n\n\nHal"); v != "Hal" {
+		t.Fatalf("got %q", v)
+	}
+	if v := f.push("lo"); v != "lo" {
+		t.Fatalf("got %q", v)
+	}
+}