fix(agent): deepseek thinking replay twilight

go.mod

@@ -21,7 +21,7 @@ require (
 	github.com/felinics/acgo v0.0.0-20260829152557-fc78bf271ef8
 	github.com/felinics/connect-it/sdk/go v0.1.1-0.20260829153217-0dcd18de667d
 	github.com/felinics/dingtalk-stream-sdk-go v0.0.0-20260829152622-ce4b7ea674a5
-	github.com/felinics/twilight v0.6.1-0.20260829152448-3e7b6144320c
+	github.com/felinics/twilight v0.6.1-0.20260908100548-18a9879d43ba
 	github.com/go-ego/gse v1.0.2
 	github.com/go-shiori/go-readability v0.0.0-20251205110129-5db1dc9836f0
 	github.com/golang-jwt/jwt/v5 v5.3.1

go.sum

@@ -237,8 +237,8 @@ github.com/felinics/connect-it/sdk/go v0.1.1-0.20260829153217-0dcd18de667d h1:4x
 github.com/felinics/connect-it/sdk/go v0.1.1-0.20260829153217-0dcd18de667d/go.mod h1:efQBEl/nBI7s7ptKhxpMIQWXMFwJA/mQlG8Y5Gx7y1k=
 github.com/felinics/dingtalk-stream-sdk-go v0.0.0-20260829152622-ce4b7ea674a5 h1:f70CJWZc4i4csjDQ50PpDVVqyc3wBFgRyGzKc/G101Q=
 github.com/felinics/dingtalk-stream-sdk-go v0.0.0-20260829152622-ce4b7ea674a5/go.mod h1:6lA5cvlc9Grmj5AgIMI0tCKB3o3M49qHzeA3rxmHZ1o=
-github.com/felinics/twilight v0.6.1-0.20260829152448-3e7b6144320c h1:R9Y6Hz04qAkhhutqUM0mkFsEGn5zYb2rQdbKU6kPuBw=
-github.com/felinics/twilight v0.6.1-0.20260829152448-3e7b6144320c/go.mod h1:ccjd58F/NP7/IUvePMhlYJRigJpIt635j4EFjNsSAAk=
+github.com/felinics/twilight v0.6.1-0.20260908100548-18a9879d43ba h1:ambJktXDrDwL8yt3XCejpLa6MI2YlS/6Tf1e7H0wLwk=
+github.com/felinics/twilight v0.6.1-0.20260908100548-18a9879d43ba/go.mod h1:ccjd58F/NP7/IUvePMhlYJRigJpIt635j4EFjNsSAAk=
 github.com/felixge/httpsnoop v1.0.4 h1:NFTV2Zj1bL4mc9sqWACXbQFVBBg2W3GPvqp8/ESS2Wg=
 github.com/felixge/httpsnoop v1.0.4/go.mod h1:m8KPJKqk1gH5J9DgRY2ASl2lWCfGKXixSwevea8zH2U=
 github.com/frankban/quicktest v1.14.3/go.mod h1:mgiwOwqx65TmIk1wJ6Q7wvnVMocbUorkibMOrVTHZps=

internal/contextview/selector_tool_exchange.go

@@ -16,9 +16,10 @@ func applyToolExchangePolicy(frags []contextfrag.ContextFrag, policy *contextfra
 		return frags, nil, nil
 	}
 	kept = make([]contextfrag.ContextFrag, 0, len(frags))
-	for _, frag := range frags {
+	openTurnStart := openTurnTailStart(frags)
+	for i, frag := range frags {
 		msg := contextfrag.FragMessage(frag)
-		if msg == nil || frag.Slot != contextfrag.SlotHistory {
+		if msg == nil || frag.Slot != contextfrag.SlotHistory || (openTurnStart >= 0 && i > openTurnStart) {
 			kept = append(kept, frag)
 			continue
 		}
@@ -54,6 +55,53 @@ func applyToolExchangePolicy(frags []contextfrag.ContextFrag, policy *contextfra
 	return kept, dropped, edits
 }
 
+// openTurnTailStart reports the slice index of the last history user message
+// when the history ends in a turn that is still being answered, or -1.
+//
+// A continuation resumed after a deferred tool call (tool approval, ask_user)
+// carries no current user message: the request replays the persisted history
+// and ends with the parked step's tool call and the result it produced. Those
+// messages are the live turn, not tool noise from an earlier exchange. Stripping
+// them leaves the model a trailing assistant text with no tool call, no result
+// and no reasoning, so it cannot see what the tool returned and re-issues the
+// call; DeepSeek thinking mode additionally rejects the request because that
+// trailing assistant message carries no reasoning_content. The tail is exempt
+// only when no current user frag exists and the last history message is a tool
+// result or an assistant message that still holds tool calls; a turn that
+// concluded with plain assistant text is finished history and strips as usual.
+func openTurnTailStart(frags []contextfrag.ContextFrag) int {
+	lastUser := -1
+	lastHistory := -1
+	for i, frag := range frags {
+		if frag.Slot == contextfrag.SlotCurrentUser || frag.Kind == contextfrag.KindCurrentUserMessage {
+			return -1
+		}
+		msg := contextfrag.FragMessage(frag)
+		if msg == nil || frag.Slot != contextfrag.SlotHistory {
+			continue
+		}
+		lastHistory = i
+		if msg.Role == sdk.MessageRoleUser {
+			lastUser = i
+		}
+	}
+	if lastUser < 0 || lastHistory <= lastUser {
+		return -1
+	}
+	last := contextfrag.FragMessage(frags[lastHistory])
+	if last.Role == sdk.MessageRoleTool {
+		return lastUser
+	}
+	if last.Role == sdk.MessageRoleAssistant {
+		for _, part := range last.Content {
+			if _, ok := part.(sdk.ToolCallPart); ok {
+				return lastUser
+			}
+		}
+	}
+	return -1
+}
+
 func countMessageFrags(frags []contextfrag.ContextFrag) int {
 	count := 0
 	for _, frag := range frags {

internal/contextview/selector_tool_exchange_test.go

@@ -62,3 +62,91 @@ func TestToolExchangePolicyThresholdAndNilPreserveEverything(t *testing.T) {
 		}
 	}
 }
+
+// continuationTailFixture models a tool-approval continuation: the history
+// replays an earlier finished turn and then the turn still being answered,
+// whose parked step (reasoning + text + exec call) already has its result. No
+// current user message exists because the continuation carries no new query.
+func continuationTailFixture() []contextfrag.ContextFrag {
+	parked := sdk.Message{Role: sdk.MessageRoleAssistant, Content: []sdk.MessagePart{
+		sdk.ReasoningPart{Format: sdk.ReasoningFormatOpenAIChat, Text: "need to touch the file"},
+		sdk.TextPart{Text: "creating it now"},
+		sdk.ToolCallPart{ToolCallID: "exec-1", ToolName: "exec", Input: map[string]any{"command": "touch /tmp/x"}},
+	}}
+	return []contextfrag.ContextFrag{
+		historyMessageFrag("h0", sdk.UserMessage("earlier question")),
+		historyMessageFrag("h1", assistantToolCallMessage("call-1", "web_search", "let me look")),
+		historyMessageFrag("h2", toolResultMessage("call-1", "web_search", "bulky result")),
+		historyMessageFrag("h3", sdk.AssistantMessage("earlier answer")),
+		historyMessageFrag("h4", sdk.UserMessage("create a file in /tmp")),
+		historyMessageFrag("h5", parked),
+		historyMessageFrag("h6", toolResultMessage("exec-1", "exec", "created")),
+	}
+}
+
+func selectedByID(result SelectionResult) map[string]contextfrag.ContextFrag {
+	out := make(map[string]contextfrag.ContextFrag, len(result.Selected))
+	for _, frag := range result.Selected {
+		out[frag.ID] = frag
+	}
+	return out
+}
+
+func TestToolExchangePolicyKeepsUnfinishedTurnTailOnContinuation(t *testing.T) {
+	t.Parallel()
+	selector := &FragmentSelector{}
+	result := selector.Select(continuationTailFixture(), selector.ProfileFor(contextfrag.IntentRunConfigPreProvider), BudgetEnvelope{ToolExchange: &contextfrag.ToolExchangePolicy{}})
+	selected := selectedByID(result)
+	if _, ok := selected["h2"]; ok {
+		t.Fatalf("earlier tool result survived: %#v", selected["h2"])
+	}
+	for _, part := range contextfrag.FragMessage(selected["h1"]).Content {
+		if _, ok := part.(sdk.ToolCallPart); ok {
+			t.Fatalf("earlier tool call survived: %#v", part)
+		}
+	}
+	parked, ok := selected["h5"]
+	if !ok {
+		t.Fatalf("parked step dropped: %#v", result.Summary.DropReasons)
+	}
+	var hasCall, hasReasoning bool
+	for _, part := range contextfrag.FragMessage(parked).Content {
+		switch part.(type) {
+		case sdk.ToolCallPart:
+			hasCall = true
+		case sdk.ReasoningPart:
+			hasReasoning = true
+		}
+	}
+	if !hasCall || !hasReasoning {
+		t.Fatalf("parked step lost its tool call or reasoning: %#v", contextfrag.FragMessage(parked).Content)
+	}
+	if _, ok := selected["h6"]; !ok {
+		t.Fatalf("parked step result dropped: %#v", result.Summary.DropReasons)
+	}
+}
+
+func TestToolExchangePolicyStripsPreviousTurnWhenCurrentUserPresent(t *testing.T) {
+	t.Parallel()
+	frags := continuationTailFixture()
+	current := sdk.UserMessage("and now a new question")
+	frags = append(frags, contextfrag.MessageFrag(contextfrag.MessageFragInput{
+		ID: "c0", Message: current, Kind: contextfrag.KindCurrentUserMessage, Slot: contextfrag.SlotCurrentUser,
+		Scope: contextfrag.Scope{BotID: "bot-1"}, Source: "run_config_fields", Collector: "materialized_current_user",
+	}))
+	selector := &FragmentSelector{}
+	result := selector.Select(frags, selector.ProfileFor(contextfrag.IntentRunConfigPreProvider), BudgetEnvelope{ToolExchange: &contextfrag.ToolExchangePolicy{}})
+	selected := selectedByID(result)
+	if _, ok := selected["h6"]; ok {
+		t.Fatalf("previous turn tool result survived with a current user message present")
+	}
+	for _, part := range contextfrag.FragMessage(selected["h5"]).Content {
+		switch part.(type) {
+		case sdk.ToolCallPart, sdk.ReasoningPart:
+			t.Fatalf("previous turn kept tool exchange part: %#v", part)
+		}
+	}
+	if _, ok := selected["c0"]; !ok {
+		t.Fatalf("current user message dropped")
+	}
+}