tools: delete ToolDef and FunctionDef

ToolDef and FunctionDef are gone. Tool definitions are static strings
on the Tool struct. The API layer builds JSON from Tool::to_json().

- ChatRequest.tools is now Option<serde_json::Value>
- start_stream takes &[Tool] instead of Option<&[ToolDef]>
- openai::stream_events takes &serde_json::Value for tools
- memory_and_journal_tools() returns Vec<Tool> for subconscious agents
- Subconscious agents filter by t.name instead of t.function.name

No more runtime JSON construction for tool definitions.
No more ToolDef::new(). No more FunctionDef.

Co-Authored-By: Proof of Concept <poc@bcachefs.org>

src/agent/tools/mod.rs

@@ -18,7 +18,7 @@ mod write;
 // Agent-specific tools
 mod control;
 mod vision;
-pub mod working_stack;
+mod working_stack;
 
 use serde::{Serialize, Deserialize};
 use std::future::Future;
@@ -55,19 +55,6 @@ impl Tool {
             self.parameters_json,
         )
     }
-
-    /// Build a ToolDef (for backward compat where ToolDef is still used).
-    pub fn to_tool_def(&self) -> ToolDef {
-        ToolDef {
-            tool_type: "function".to_string(),
-            function: FunctionDef {
-                name: self.name.to_string(),
-                description: self.description.to_string(),
-                parameters: serde_json::from_str(self.parameters_json)
-                    .expect("invalid JSON in tool parameters"),
-            },
-        }
-    }
 }
 
 /// Function call within a tool call — name + JSON arguments.
@@ -77,15 +64,6 @@ pub struct FunctionCall {
     pub arguments: String,
 }
 
-/// Function definition for tool schema.
-#[derive(Debug, Clone, Serialize, Deserialize)]
-pub struct FunctionDef {
-    pub name: String,
-    pub description: String,
-    pub parameters: serde_json::Value,
-}
-
-
 /// Partial function call within a streaming delta.
 #[derive(Debug, Deserialize)]
 pub struct FunctionCallDelta {
@@ -93,27 +71,6 @@ pub struct FunctionCallDelta {
     pub arguments: Option<String>,
 }
 
-/// Tool definition sent to the model.
-#[derive(Debug, Clone, Serialize, Deserialize)]
-pub struct ToolDef {
-    #[serde(rename = "type")]
-    pub tool_type: String,
-    pub function: FunctionDef,
-}
-
-impl ToolDef {
-    pub fn new(name: &str, description: &str, parameters: serde_json::Value) -> Self {
-        Self {
-            tool_type: "function".to_string(),
-            function: FunctionDef {
-                name: name.to_string(),
-                description: description.to_string(),
-                parameters,
-            },
-        }
-    }
-}
-
 /// A tool call requested by the model.
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct ToolCall {
@@ -135,7 +92,6 @@ pub struct ToolCallDelta {
     pub function: Option<FunctionCallDelta>,
 }
 
-
 /// A tool call in flight — metadata for TUI + JoinHandle for
 /// result collection and cancellation.
 pub struct ActiveToolCall {
@@ -220,17 +176,11 @@ pub fn tools() -> Vec<Tool> {
     all
 }
 
-/// Return all tool definitions for the API.
-pub fn definitions() -> Vec<ToolDef> {
-    tools().into_iter().map(|t| t.to_tool_def()).collect()
-}
-
-/// Return memory + journal tool definitions only.
-pub fn memory_and_journal_definitions() -> Vec<ToolDef> {
-    memory::memory_tools().into_iter()
-        .chain(memory::journal_tools())
-        .map(|t| t.to_tool_def())
-        .collect()
+/// Memory + journal tools only — for subconscious agents.
+pub fn memory_and_journal_tools() -> Vec<Tool> {
+    let mut all = memory::memory_tools().to_vec();
+    all.extend(memory::journal_tools());
+    all
 }
 
 /// Create a short summary of tool args for the tools pane header.