R1: move tool registry off Config onto Agent

The tool set is no longer part of the per-turn Config snapshot. Agent now
owns a ToolRegistry (created empty at init), populated via the new
Agent.registerTool / registerToolSource methods. openStream and
OpenStreamFn take the registry as an explicit parameter rather than reading
it from cfg.registry, so swapping provider/model between turns (setConfig)
no longer disturbs the tool set.

CLI migrated to register the Lua tool source onto the agent instead of a
locally-owned registry. Test harnesses updated to stage tools on the agent.

1 files changed, 6 insertions, 11 deletions

diff --git a/src/main.zig b/src/main.zig
index ff00689..46b6320 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -365,21 +365,16 @@ pub fn main(init: std.process.Init) !void {
         );
     }
 
-    // The tool registry is owned here and referenced by the active config
-    // snapshot. Extensions register their tool source into it *after* the
-    // agent is built; the agent holds a `*const Config` pointing at this
-    // registry, so in-place registration before the first turn is visible.
-    var registry = panto.ToolRegistry.init(alloc);
-    defer registry.deinit();
-
     // Assemble the active configuration snapshot and build the agent now,
     // before luarocks bootstrap and extension loading. The agent adopts the
     // store (for free persistence) and the resumed conversation (or starts
-    // fresh). System-prompt seeding/reconciliation below runs *through* the
-    // agent so those entries persist.
+    // fresh). The agent owns its own tool registry (post-R1); extensions
+    // register their tool source onto it *after* the agent is built but
+    // before the first turn, so in-place registration is visible.
+    // System-prompt seeding/reconciliation below runs *through* the agent
+    // so those entries persist.
     const active_config: panto.config.Config = .{
         .provider = provider_config,
-        .registry = &registry,
         .compaction = compaction_cfg,
     };
     var agent = panto.agent.Agent.init(
@@ -468,7 +463,7 @@ pub fn main(init: std.process.Init) !void {
     std.log.debug("extensions: {d} tool(s) registered", .{n_ext_tools});
 
     if (n_ext_tools > 0) {
-        try registry.registerSource(rt.toolSource());
+        try agent.registerToolSource(rt.toolSource());
     }
 
     // Resolve the compaction system prompt (COMPACTION.md across layers,