harness: proactive send mode + persistent backlog seen-state

- 'matrix_harness send "text"' — one-shot unprompted messaging to the
  pinned room (agent announcements/alerts)
- backlog no longer re-forwards read messages: last homeserver
  origin_server_ts persisted to /tmp/matrix-harness.state, advanced on
  every processed event; events at/below it are skipped
- 30-min staleness window retained as outer bound

src/matrix_harness.zig

@@ -20,9 +20,68 @@ fn env_or(name: [:0]const u8, default: []const u8) []const u8 {
     return default;
 }
 
+/// One-shot proactive send: `matrix_harness send "message body"`.
+/// Lets the agent reach Pierre unprompted (announcements, alerts).
+fn runSend(alloc: std.mem.Allocator, io: std.Io, text: []const u8) !void {
+    letta.initConversationsDir();
+    const user = env_or("MATRIX_USER", "@chaos-prime:chaosmith.systems");
+    const password = env_or("MATRIX_PASSWORD", "");
+    const room = env_or("MATRIX_ROOM", "");
+    if (password.len == 0 or room.len == 0) {
+        std.debug.print("matrix_harness send: MATRIX_PASSWORD and MATRIX_ROOM required\n", .{});
+        return error.NoCredentials;
+    }
+    const session = try matrix.login(alloc, io, user, password);
+    defer alloc.free(session.token);
+    defer alloc.free(session.user_id);
+    const ev_id = try matrix.sendText(alloc, io, session.token, room, text);
+    std.debug.print("matrix_harness: sent {s}\n", .{ev_id});
+    alloc.free(ev_id);
+}
+
+/// Persistent seen-state: last homeserver event timestamp we already
+/// forwarded. Survives restarts so backlog never re-sends read messages.
+const STATE_FILE = "/tmp/matrix-harness.state";
+
+fn loadSeenTs(io: std.Io) i64 {
+    var f = std.Io.Dir.openFileAbsolute(io, STATE_FILE, .{}) catch return 0;
+    defer f.close(io);
+    var buf: [64]u8 = undefined;
+    var rbuf: [64]u8 = undefined;
+    var r = f.reader(io, &rbuf);
+    const n = r.interface.readSliceShort(&buf) catch return 0;
+    return std.fmt.parseInt(i64, std.mem.trim(u8, buf[0..n], " \n"), 10) catch 0;
+}
+
+fn saveSeenTs(io: std.Io, ts: i64) void {
+    const f = std.Io.Dir.createFileAbsolute(io, STATE_FILE, .{ .truncate = true }) catch return;
+    var buf: [24]u8 = undefined;
+    const body = std.fmt.bufPrint(&buf, "{d}\n", .{ts}) catch return;
+    var wbuf: [64]u8 = undefined;
+    var w = f.writer(io, &wbuf);
+    w.interface.writeAll(body) catch {};
+    w.interface.flush() catch {};
+    f.close(io);
+}
+
 pub fn main(init: std.process.Init) !void {
     const alloc = init.gpa;
     const io = init.io;
+
+    // Proactive-send mode: `matrix_harness send "text"`.
+    {
+        var args_it = std.process.Args.Iterator.init(init.minimal.args);
+        _ = args_it.next(); // program name
+        const first_arg = args_it.next();
+        if (first_arg != null and std.mem.eql(u8, first_arg.?, "send")) {
+            if (args_it.next()) |msg| {
+                return runSend(alloc, io, msg);
+            }
+            std.debug.print("usage: matrix_harness send \"message\"\n", .{});
+            return error.MissingMessage;
+        }
+    }
+
     letta.initConversationsDir();
 
     const user = env_or("MATRIX_USER", "@chaos-prime:chaosmith.systems");
@@ -65,14 +124,18 @@ pub fn main(init: std.process.Init) !void {
     const first = try matrix.sync(alloc, io, session.token, "", 0);
     {
         const now_ms: i64 = @intCast(@divTrunc(std.Io.Clock.now(.real, io).nanoseconds, std.time.ns_per_ms));
+        const seen_ts = loadSeenTs(io);
+        var new_max = seen_ts;
         var backlog: std.ArrayListUnmanaged(u8) = .empty;
         defer backlog.deinit(alloc);
         for (first.events) |ev| {
             defer alloc.free(ev.sender);
             defer alloc.free(ev.body);
+            if (ev.ts > new_max) new_max = ev.ts;
             if (!std.mem.eql(u8, ev.sender, peer)) continue;
             if (ev.body.len == 0) continue;
             if (ev.ts > 0 and now_ms - ev.ts > 30 * 60 * 1000) continue; // stale
+            if (ev.ts > 0 and ev.ts <= seen_ts) continue; // already seen/answered
             try backlog.appendSlice(alloc, ev.sender);
             try backlog.appendSlice(alloc, ": ");
             try backlog.appendSlice(alloc, ev.body);
@@ -91,6 +154,9 @@ pub fn main(init: std.process.Init) !void {
                 std.debug.print("matrix_harness: backlog letta failed: {s} (skipping)\n", .{@errorName(e)});
             }
         }
+        // Advance persisted seen-state even when nothing was forwarded:
+        // "read up to here" is authoritative from the homeserver ts.
+        saveSeenTs(io, new_max);
     }
     alloc.free(first.events);
     var since = first.next;
@@ -109,6 +175,7 @@ pub fn main(init: std.process.Init) !void {
         for (result.events) |ev| {
             defer alloc.free(ev.sender);
             defer alloc.free(ev.body);
+            defer if (ev.ts > 0) saveSeenTs(io, ev.ts);
             // Only peer messages (skip own sends and server noise).
             if (!std.mem.eql(u8, ev.sender, peer)) continue;
             if (ev.body.len == 0) continue;