From 6fc2e001acd72f7a8ecfcf615338fc2523e4e894 Mon Sep 17 00:00:00 2001
From: Levi Neely <lneely@pascom.net>
Date: Thu, 30 Jul 2026 09:24:08 +0200
Subject: [PATCH] tools: promote reasoning_think to builtin
MIME-Version: 1.0
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Zero-context-cost scratchpad tool. The thought is recorded in history
but returns empty — no output tokens wasted. Registered in ListTools
schema and builtins map.
---
 tools/builtins.go  | 15 ++++++++-------
 tools/reasoning.go | 25 +++++++++++++++++++++++++
 toolsrv/server.go  | 11 +++++++++++
 3 files changed, 44 insertions(+), 7 deletions(-)
 create mode 100644 tools/reasoning.go

diff --git a/tools/builtins.go b/tools/builtins.go
index d1db7e1..fc6d4e1 100644
--- a/tools/builtins.go
+++ b/tools/builtins.go
@@ -7,12 +7,13 @@ import "ollie/toolsrv"
 // Builtins returns the default set of built-in tool handlers.
 func Builtins() map[string]toolsrv.Handler {
 	return map[string]toolsrv.Handler{
-		"shell":        Shell,
-		"tool_list":    ToolList,
-		"tool_load":    ToolLoad,
-		"tool_active":  ToolActive,
-		"skill_list":   SkillList,
-		"skill_load":   SkillLoad,
-		"skill_active": SkillActive,
+		"shell":           Shell,
+		"reasoning_think": Think,
+		"tool_list":       ToolList,
+		"tool_load":       ToolLoad,
+		"tool_active":     ToolActive,
+		"skill_list":      SkillList,
+		"skill_load":      SkillLoad,
+		"skill_active":    SkillActive,
 	}
 }
diff --git a/tools/reasoning.go b/tools/reasoning.go
new file mode 100644
index 0000000..fa35ebd
--- /dev/null
+++ b/tools/reasoning.go
@@ -0,0 +1,25 @@
+package tools
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+
+	"ollie/toolsrv"
+)
+
+// Think is a scratchpad for externalizing reasoning. The thought is recorded
+// in conversation history but not shown to the user. Takes up practically
+// zero context space — the value is in writing it.
+func Think(ctx context.Context, srv *toolsrv.Server, args json.RawMessage) (string, error) {
+	var a struct {
+		Thought string `json:"thought"`
+	}
+	if err := json.Unmarshal(args, &a); err != nil {
+		return "", fmt.Errorf("reasoning_think: bad args: %w", err)
+	}
+	if a.Thought == "" {
+		return "", fmt.Errorf("reasoning_think: thought is required")
+	}
+	return "", nil
+}
diff --git a/toolsrv/server.go b/toolsrv/server.go
index 6b5b84a..748c779 100644
--- a/toolsrv/server.go
+++ b/toolsrv/server.go
@@ -201,6 +201,17 @@ Returns tools with descriptions, one per line.`,
 				"properties": {}
 			}`),
 		},
+		{
+			Name: "reasoning_think",
+			Description: `Scratchpad for externalizing reasoning. Recorded in history but not shown to the user.`,
+			InputSchema: json.RawMessage(`{
+				"type": "object",
+				"required": ["thought"],
+				"properties": {
+					"thought": {"type": "string", "description": "Your reasoning."}
+				}
+			}`),
+		},
 	}
 
 	if e.toolRegistry != nil && e.sessionID != "" {