R2: redesign session store with wire-format identity

Replace the single-session SessionManager seam with a directory-backed
catalog. session_manager.zig -> file_system_jsonl_store.zig; the old
machinery becomes internal SessionFile, and a new FileSystemJSONLStore
implements the redesigned SessionStore vtable (create/list/resolve/latest/
load/appendMessages) minting Session/SessionInfo handles.

Session logs now record wire-format provider identity
({api_style, base_url, model, reasoning}) instead of a single provider
string or CLI aliases; no api_key material is ever stored. Disk* content
types renamed Stored*; the rich audit-oriented write record is
PersistentMessage (in-memory Message + WireIdentity + provenance).

Agent.init now takes a Session; persist_provider/persist_model display
strings deleted (banner stays alias-based, resume picks default model).
Message.metadata round-trips. Dangling-prompt recovery dropped. CLI
migrated to the catalog store for run/resume/list. Clean break, no version
bump (old logs wiped).

1 files changed, 6 insertions, 2 deletions

diff --git a/src/subcommand.zig b/src/subcommand.zig
index c50429e..3ccd2c6 100644
--- a/src/subcommand.zig
+++ b/src/subcommand.zig
@@ -272,8 +272,12 @@ fn runSessionsSubcommand(
     const session_dir = try session_paths.sessionDirForCwd(allocator, environ_map, cwd);
     defer allocator.free(session_dir);
 
-    const infos = try panto.session_manager.listSessions(allocator, io, session_dir, null);
-    defer panto.session_manager.freeSessionInfos(allocator, infos);
+    var store_impl = try panto.session_manager.FileSystemJSONLStore.init(allocator, io, session_dir, cwd);
+    defer store_impl.deinit();
+    const store = store_impl.store();
+
+    const infos = try store.list();
+    defer store.freeSessionInfos(infos);
 
     var stdout_buffer: [4096]u8 = undefined;
     var stdout_file = std.Io.File.stdout().writer(io, &stdout_buffer);