Stage and apply event-field overrides at tool lifecycle boundaries

Stage writable event-field overrides by tool call id so they can be applied at the correct point in the turn lifecycle. Capture input overrides from tool_call_complete, capture output overrides from tool_result, and clear staged overrides defensively at turn start and shutdown.

Also honor user_message text overrides when starting a turn, add the helper that applies staged overrides to the agent at dispatch boundaries, and cover the behavior with tests for staged input/output overrides.

1 files changed, 4 insertions, 0 deletions

diff --git a/src/main.zig b/src/main.zig
index 86f1cb1..02c0045 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -383,6 +383,10 @@ pub fn main(init: std.process.Init) !void {
     // any extension loads (which `require('panto')`).
     try rt.installPantoModule();
 
+    // Hand extensions the live session agent (`panto.ext.agent`) so an
+    // `activate()` can act on the session directly (add_system_message…).
+    try rt.setExtAgent(agent);
+
     // luv is installed (or already present) at this point; wire the
     // libuv-driven coroutine scheduler before any extensions get a
     // chance to register tools that might want to yield.