1 files changed, 49 insertions, 35 deletions

diff --git a/libpanto/src/tool.zig b/libpanto/src/tool.zig
index 60a7736..c96dfee 100644
--- a/libpanto/src/tool.zig
+++ b/libpanto/src/tool.zig
@@ -31,10 +31,11 @@ pub const MediaPart = struct {
     data: []const u8,
 };
 
-/// One element of a tool's result. A tool returns a `[]ResultPart`; the
-/// agent assembles these into a `ToolResultBlock`. Bytes referenced by a
-/// part are owned by the allocator passed to `invoke` / `invoke_batch`;
-/// ownership transfers to the agent, which frees them.
+/// One element of a tool's result. A tool returns a `ResultParts` (a thin
+/// wrapper around `[]ResultPart`); the agent assembles these into a
+/// `ToolResultBlock`. Bytes referenced by a part are owned by the allocator
+/// passed to `invoke` / `invoke_batch`; ownership transfers to the agent,
+/// which frees them.
 pub const ResultPart = union(enum) {
     text: []const u8,
     media: MediaPart,
@@ -51,11 +52,42 @@ pub const ResultPart = union(enum) {
     }
 };
 
-/// Free a `[]ResultPart` and every part it owns.
-pub fn freeResultParts(allocator: Allocator, parts: []ResultPart) void {
-    for (parts) |p| p.deinit(allocator);
-    allocator.free(parts);
-}
+/// A tool's full result: an owned slice of `ResultPart`s. The value the
+/// `Tool`/`ToolSource` vtable returns and the agent loop assembles — a thin
+/// wrapper around `[]ResultPart` that carries the construction/teardown
+/// ergonomics a bare slice alias can't. Build one with
+/// `fromText`/`fromTextOwned` (or wrap a hand-built slice as
+/// `.{ .items = slice }`); release it (slice + every part's bytes) with
+/// `deinit`.
+pub const ResultParts = struct {
+    items: []ResultPart,
+
+    /// A single text part that owns `text` (duped from the input slice).
+    pub fn fromText(allocator: Allocator, text: []const u8) !ResultParts {
+        const owned = try allocator.dupe(u8, text);
+        errdefer allocator.free(owned);
+        const parts = try allocator.alloc(ResultPart, 1);
+        parts[0] = .{ .text = owned };
+        return .{ .items = parts };
+    }
+
+    /// A single text part wrapping an already-owned `text` slice. Takes
+    /// ownership of `text` (frees it if the allocation below fails).
+    pub fn fromTextOwned(allocator: Allocator, text: []u8) !ResultParts {
+        const parts = allocator.alloc(ResultPart, 1) catch |e| {
+            allocator.free(text);
+            return e;
+        };
+        parts[0] = .{ .text = text };
+        return .{ .items = parts };
+    }
+
+    /// Free the slice and every part it owns.
+    pub fn deinit(self: ResultParts, allocator: Allocator) void {
+        for (self.items) |p| p.deinit(allocator);
+        allocator.free(self.items);
+    }
+};
 
 pub const Tool = struct {
     /// Metadata: `name`, `description`, `schema_json`. Borrowed — the
@@ -78,11 +110,13 @@ pub const Tool = struct {
         /// `input` is the raw JSON bytes the provider sent. The tool is
         /// responsible for parsing them if it cares about their structure.
         ///
-        /// Returns an owned slice of `ResultPart`s allocated with
-        /// `allocator`; each part's bytes are likewise owned. These become
-        /// the parts of the ToolResult block sent back to the LLM. The
-        /// agent takes ownership and frees the slice and every part (see
-        /// `freeResultParts`).
+        /// Returns a `ResultParts` allocated with `allocator`; each part's
+        /// bytes are likewise owned. These become the parts of the
+        /// ToolResult block sent back to the LLM. The agent takes ownership
+        /// and frees the slice and every part (see `ResultParts.deinit`).
+        /// Build the return value with `ResultParts.fromText` /
+        /// `.fromTextOwned` for the common single-text case, or wrap a
+        /// hand-built slice as `.{ .items = slice }`.
         ///
         /// Returning an error normally becomes a model-visible error
         /// `ToolResult`: the agent synthesizes an error result for this
@@ -100,7 +134,7 @@ pub const Tool = struct {
             ctx: *anyopaque,
             input: []const u8,
             allocator: Allocator,
-        ) anyerror![]ResultPart,
+        ) anyerror!ResultParts,
 
         /// Called when the tool is unregistered or the registry is torn
         /// down. Frees any resources owned by `ctx`, including `ctx`
@@ -113,23 +147,3 @@ pub const Tool = struct {
     };
 };
 
-/// Convenience: allocate a single-element `[]ResultPart` holding one text
-/// part that owns `text` (duped from the input slice).
-pub fn textResult(allocator: Allocator, text: []const u8) ![]ResultPart {
-    const owned = try allocator.dupe(u8, text);
-    errdefer allocator.free(owned);
-    const parts = try allocator.alloc(ResultPart, 1);
-    parts[0] = .{ .text = owned };
-    return parts;
-}
-
-/// Convenience: wrap an already-owned `text` slice as a single-element
-/// `[]ResultPart`. Takes ownership of `text`.
-pub fn ownedTextResult(allocator: Allocator, text: []u8) ![]ResultPart {
-    const parts = allocator.alloc(ResultPart, 1) catch |e| {
-        allocator.free(text);
-        return e;
-    };
-    parts[0] = .{ .text = text };
-    return parts;
-}