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|
//! Turn → session-log persistence: map in-memory `Conversation` messages
//! to rich `PersistentMessage` write records and append them through a
//! `Session` handle.
//!
//! This logic lives in `libpanto` and is called by the `Agent` itself, so
//! every embedder gets persistence for free. The functions here are
//! stateless helpers over a `Session`; the agent owns the store and the
//! conversation.
//!
//! The write record is **maximalist** (full wire identity + usage + the
//! entire current conversation + the offered tool set). The library offers
//! it all on every append; each store keeps what it wants. `PersistentMessage`
//! borrows the in-memory `Message` directly — no disk conversion happens
//! here; the store does its own serialization.
//!
//! Per-message usage is read directly off `Message.usage`.
const std = @import("std");
const Allocator = std.mem.Allocator;
const conversation = @import("conversation.zig");
const session_store = @import("session_store.zig");
const PersistentMessage = session_store.PersistentMessage;
const WireIdentity = session_store.WireIdentity;
const ToolDecl = session_store.ToolDecl;
const Session = session_store.Session;
/// Persist every conversation message at index `>= start_index` through
/// `session` as a single atomic batch.
///
/// Each `PersistentMessage` borrows the in-memory `Message`, the full
/// current conversation, and `tools` (the offered tool set) — all owned by
/// the caller and valid for the duration of the call. The wire `identity`
/// is stamped on every message; the store decides per-role what to keep
/// (the FS store drops the stamp on system entries).
///
/// An assistant message carrying a ToolUse with no following matching
/// ToolResult is skipped (a dangling tool call from an interrupted turn);
/// persisting it would make the log un-replayable.
pub fn persistTurn(
alloc: Allocator,
session: *Session,
conv: *const conversation.Conversation,
start_index: usize,
identity: WireIdentity,
tools: []const ToolDecl,
) !void {
var batch: std.ArrayList(PersistentMessage) = .empty;
defer batch.deinit(alloc);
const all_messages = conv.messages.items;
var i = start_index;
while (i < all_messages.len) : (i += 1) {
const msg = all_messages[i];
if (msg.role == .assistant and hasToolUseWithoutFollowingResults(conv, i)) {
continue;
}
try batch.append(alloc, .{
.message = msg,
.usage = msg.usage,
.identity = identity,
.conversation = all_messages,
.tools_available = tools,
});
}
if (batch.items.len == 0) return;
try session.append(batch.items);
}
/// Persist a compaction result. The agent rewrote the conversation to
/// `[system..., summary, kept-suffix...]`; persist everything from the
/// latest compaction summary onward as fresh entries.
pub fn persistCompaction(
alloc: Allocator,
session: *Session,
conv: *const conversation.Conversation,
identity: WireIdentity,
tools: []const ToolDecl,
) !void {
const start = conversation.latestCompactionIndex(conv.messages.items) orelse return;
try persistTurn(alloc, session, conv, start, identity, tools);
}
/// True when the assistant message at `index` contains a ToolUse block
/// with no matching ToolResult in the immediately following user message
/// — i.e. a dangling tool call (e.g. a turn cut short by an error).
pub fn hasToolUseWithoutFollowingResults(
conv: *const conversation.Conversation,
index: usize,
) bool {
const msg = conv.messages.items[index];
for (msg.content.items) |block| {
if (block != .ToolUse) continue;
if (index + 1 >= conv.messages.items.len) return true;
const next = conv.messages.items[index + 1];
if (next.role != .user) return true;
var found = false;
for (next.content.items) |next_block| {
if (next_block == .ToolResult and std.mem.eql(u8, next_block.ToolResult.tool_use_id, block.ToolUse.id)) {
found = true;
break;
}
}
if (!found) return true;
}
return false;
}
|
