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, 120 insertions, 120 deletions

diff --git a/libpanto/src/agent.zig b/libpanto/src/agent.zig
index e8be325..604ee55 100644
--- a/libpanto/src/agent.zig
+++ b/libpanto/src/agent.zig
@@ -197,20 +197,12 @@ pub const Agent = struct {
     /// at `init`); torn down in `deinit`. Turn-driving methods operate on
     /// this directly rather than taking a `*Conversation` parameter.
     conversation: conversation.Conversation,
-    /// Pluggable persistence backend. Every message that enters
-    /// `conversation` is persisted here as it is added. Defaults to a no-op
-    /// `NullStore` so embedders/tests that don't care about persistence
-    /// keep working. Borrowed: the embedder owns the concrete store and
-    /// must outlive the agent.
-    session_store: session_store_mod.SessionStore,
-    /// Display provider/model names used to stamp persisted entries. These
-    /// are the embedder's user-facing identity strings (e.g. the
-    /// `"provider:model"` ref's parts), which can't be derived from the
-    /// `ProviderConfig` snapshot (it only carries the `APIStyle` tag and
-    /// the raw model string). Borrowed; lifetime owned by the embedder. The
-    /// model defaults to the config snapshot's model when left empty.
-    persist_provider: []const u8 = "",
-    persist_model: []const u8 = "",
+    /// The session this agent appends to. Minted from the store at `init`
+    /// (fresh: `store.create()`) or supplied by the embedder on resume
+    /// (`resolve`/`latest`). `Session.append` proxies to the store and
+    /// updates the session's last-used wire identity. The embedder owns the
+    /// underlying store, which must outlive the agent.
+    session: session_store_mod.Session,
     /// Injectable streaming seam. Defaults to the real provider dispatch
     /// (`provider_mod.openStream`); tests override it with a stub.
     open_stream_fn: provider_mod.OpenStreamFn = provider_mod.openStream,
@@ -239,7 +231,7 @@ pub const Agent = struct {
         allocator: Allocator,
         io: Io,
         config: *const Config,
-        store: session_store_mod.SessionStore,
+        session: session_store_mod.Session,
         maybe_conversation: ?conversation.Conversation,
     ) Agent {
         return .{
@@ -248,16 +240,18 @@ pub const Agent = struct {
             .config = config,
             .registry = ToolRegistry.init(allocator),
             .conversation = maybe_conversation orelse conversation.Conversation.init(allocator),
-            .session_store = store,
+            .session = session,
         };
     }
 
     pub fn deinit(self: *Agent) void {
-        // The agent owns the conversation and the tool registry; it borrows
-        // the config snapshot and the session store, which the embedder
-        // tears down.
+        // The agent owns the conversation, the tool registry, and the
+        // session handle's `info` (minted by `store.create()` or resolved
+        // by the embedder and handed in). It borrows the config snapshot
+        // and the underlying store, which the embedder tears down.
         self.registry.deinit();
         self.conversation.deinit();
+        self.session.info.deinit(self.allocator);
     }
 
     /// Add a single tool to this agent's tool set. Visible at the next turn.
@@ -271,22 +265,11 @@ pub const Agent = struct {
         try self.registry.registerSource(src);
     }
 
-    /// The provider/model identity used to stamp persisted entries. Uses
-    /// the embedder-supplied display names when set, falling back to the
-    /// active config snapshot's model string (and the `APIStyle` tag name
-    /// for the provider) when not.
-    fn providerModel(self: *const Agent) struct { provider: []const u8, model: []const u8 } {
-        const cfg_model = switch (self.config.provider) {
-            inline else => |c| c.model,
-        };
-        const provider = if (self.persist_provider.len > 0)
-            self.persist_provider
-        else switch (self.config.provider) {
-            .openai_chat => "openai_chat",
-            .anthropic_messages => "anthropic_messages",
-        };
-        const model = if (self.persist_model.len > 0) self.persist_model else cfg_model;
-        return .{ .provider = provider, .model = model };
+    /// The wire-format provider identity stamped on persisted entries,
+    /// derived from the active config snapshot. Ground truth: never a CLI
+    /// alias, never any `api_key` material.
+    fn wireIdentity(self: *const Agent) session_store_mod.WireIdentity {
+        return self.config.provider.wireIdentity();
     }
 
     /// Swap the active configuration snapshot. Takes effect at the start of
@@ -312,14 +295,13 @@ pub const Agent = struct {
             .append => try self.conversation.addSystemMessage(text),
             .replace => try self.conversation.replaceSystemMessage(text),
         }
-        const pm = self.providerModel();
         try turn_persist.persistTurn(
             self.allocator,
-            self.session_store,
+            &self.session,
             &self.conversation,
             start,
-            pm.provider,
-            pm.model,
+            self.wireIdentity(),
+            &.{},
         );
     }
 
@@ -355,14 +337,13 @@ pub const Agent = struct {
         // recovery guarantee).
         const user_start = self.conversation.messages.items.len;
         try self.conversation.addUserMessage(message.text);
-        const pm = self.providerModel();
         try turn_persist.persistTurn(
             self.allocator,
-            self.session_store,
+            &self.session,
             &self.conversation,
             user_start,
-            pm.provider,
-            pm.model,
+            self.wireIdentity(),
+            &.{},
         );
 
         const s = try self.allocator.create(Stream);
@@ -375,23 +356,23 @@ pub const Agent = struct {
     /// `[system..., summary, kept-suffix...]`), so persist the whole
     /// post-compaction window instead of `[start..]`.
     fn persistTurnTail(self: *Agent, start: usize) !void {
-        const pm = self.providerModel();
+        const id = self.wireIdentity();
         if (self.auto_compacted) {
             try turn_persist.persistCompaction(
                 self.allocator,
-                self.session_store,
+                &self.session,
                 &self.conversation,
-                pm.provider,
-                pm.model,
+                id,
+                &.{},
             );
         } else {
             try turn_persist.persistTurn(
                 self.allocator,
-                self.session_store,
+                &self.session,
                 &self.conversation,
                 start,
-                pm.provider,
-                pm.model,
+                id,
+                &.{},
             );
         }
     }
@@ -621,13 +602,12 @@ pub const Agent = struct {
     ) !CompactionResult {
         const res = try self.compact(system_prompt, extra_instructions);
         if (res.compacted) {
-            const pm = self.providerModel();
             try turn_persist.persistCompaction(
                 self.allocator,
-                self.session_store,
+                &self.session,
                 &self.conversation,
-                pm.provider,
-                pm.model,
+                self.wireIdentity(),
+                &.{},
             );
         }
         return res;
@@ -1798,59 +1778,81 @@ const HardFailTool = struct {
 };
 
 /// An in-memory `SessionStore` test double: records every appended
-/// `DiskMessage` (role + provider/model stamp) so tests can assert the
+/// `StoredMessage` (role + provider/model stamp) so tests can assert the
 /// agent persisted the right turn without touching disk. Honors the store
 /// ownership contract by freeing each consumed message after recording its
 /// salient fields.
 const CapturingStore = struct {
     allocator: Allocator,
-    roles: std.ArrayList(session_store_mod.DiskMessageRole) = .empty,
-    providers: std.ArrayList(?[]const u8) = .empty,
+    roles: std.ArrayList(conversation.MessageRole) = .empty,
+    base_urls: std.ArrayList([]const u8) = .empty,
 
     fn init(allocator: Allocator) CapturingStore {
         return .{ .allocator = allocator };
     }
 
     fn deinit(self: *CapturingStore) void {
-        for (self.providers.items) |p| if (p) |s| self.allocator.free(s);
-        self.providers.deinit(self.allocator);
+        for (self.base_urls.items) |s| self.allocator.free(s);
+        self.base_urls.deinit(self.allocator);
         self.roles.deinit(self.allocator);
     }
 
-    fn appendMessagesVT(
-        ctx: *anyopaque,
-        messages: []session_store_mod.DiskMessage,
-        providers: []const ?[]const u8,
-        _: []const ?[]const u8,
-    ) anyerror!void {
+    fn createVT(ctx: *anyopaque) session_store_mod.Session {
         const self: *CapturingStore = @ptrCast(@alignCast(ctx));
-        for (messages, 0..) |m, i| {
-            try self.roles.append(self.allocator, m.role);
-            // Prefer the assistant message's own provider stamp, else the
-            // entry-level provider stamp (user messages).
-            const prov = m.provider orelse providers[i];
-            const dup: ?[]const u8 = if (prov) |p| try self.allocator.dupe(u8, p) else null;
-            try self.providers.append(self.allocator, dup);
-        }
-        // Contract: appends consume their messages.
-        for (messages) |m| m.deinit(self.allocator);
+        const a = self.allocator;
+        const info: session_store_mod.SessionInfo = .{
+            .id = a.dupe(u8, "cap") catch "cap",
+            .created = a.dupe(u8, "") catch "",
+            .modified = a.dupe(u8, "") catch "",
+            .message_count = 0,
+            .last_user_message = a.dupe(u8, "") catch "",
+            .api_style = .openai_chat,
+            .base_url = a.dupe(u8, "") catch "",
+            .model = a.dupe(u8, "") catch "",
+            .reasoning = .default,
+        };
+        return .{ .info = info, .store = self.store() };
     }
 
-    fn loadConversationVT(_: *anyopaque, alloc: Allocator) anyerror!session_store_mod.LoadedSession {
-        return .{ .conversation = conversation.Conversation.init(alloc), .dangling_user = null };
+    fn listVT(ctx: *anyopaque) anyerror![]session_store_mod.SessionInfo {
+        const self: *CapturingStore = @ptrCast(@alignCast(ctx));
+        return self.allocator.alloc(session_store_mod.SessionInfo, 0);
+    }
+    fn freeSessionInfosVT(ctx: *anyopaque, infos: []session_store_mod.SessionInfo) void {
+        const self: *CapturingStore = @ptrCast(@alignCast(ctx));
+        for (infos) |i| i.deinit(self.allocator);
+        self.allocator.free(infos);
     }
-    fn sessionIdVT(_: *anyopaque) []const u8 {
-        return "cap";
+    fn resolveVT(_: *anyopaque, _: []const u8) anyerror!?session_store_mod.Session {
+        return null;
+    }
+    fn latestVT(_: *anyopaque) anyerror!?session_store_mod.Session {
+        return null;
     }
-    fn activeModelVT(_: *anyopaque) ?session_store_mod.ActiveModel {
+    fn loadVT(_: *anyopaque, _: []const u8) anyerror!?conversation.Conversation {
         return null;
     }
 
+    fn appendMessagesVT(
+        ctx: *anyopaque,
+        _: []const u8,
+        messages: []session_store_mod.PersistentMessage,
+    ) anyerror!void {
+        const self: *CapturingStore = @ptrCast(@alignCast(ctx));
+        for (messages) |m| {
+            try self.roles.append(self.allocator, m.message.role);
+            try self.base_urls.append(self.allocator, try self.allocator.dupe(u8, m.identity.base_url));
+        }
+    }
+
     const vtable: session_store_mod.SessionStore.VTable = .{
+        .create = createVT,
+        .list = listVT,
+        .freeSessionInfos = freeSessionInfosVT,
+        .resolve = resolveVT,
+        .latest = latestVT,
+        .load = loadVT,
         .appendMessages = appendMessagesVT,
-        .loadConversation = loadConversationVT,
-        .sessionId = sessionIdVT,
-        .activeModel = activeModelVT,
     };
 
     fn store(self: *CapturingStore) session_store_mod.SessionStore {
@@ -1880,27 +1882,25 @@ test "agent persists user, assistant, and tool-result messages of a turn" {
 
     var cap = CapturingStore.init(allocator);
     defer cap.deinit();
-    var agent = Agent.init(allocator, io, &h.config, cap.store(), null);
+    var agent = Agent.init(allocator, io, &h.config, cap.store().create(), null);
     defer agent.deinit();
     h.seedInto(&agent);
     agent.open_stream_fn = stub.install();
-    agent.persist_provider = "openai";
-    agent.persist_model = "gpt-4o";
 
     try drainTurn(&agent, "call a tool");
 
     // Persisted, in order: user prompt, assistant(ToolUse), user(ToolResult),
     // assistant(text).
     try testing.expectEqual(@as(usize, 4), cap.roles.items.len);
-    try testing.expectEqual(session_store_mod.DiskMessageRole.user, cap.roles.items[0]);
-    try testing.expectEqual(session_store_mod.DiskMessageRole.assistant, cap.roles.items[1]);
-    try testing.expectEqual(session_store_mod.DiskMessageRole.user, cap.roles.items[2]);
-    try testing.expectEqual(session_store_mod.DiskMessageRole.assistant, cap.roles.items[3]);
+    try testing.expectEqual(conversation.MessageRole.user, cap.roles.items[0]);
+    try testing.expectEqual(conversation.MessageRole.assistant, cap.roles.items[1]);
+    try testing.expectEqual(conversation.MessageRole.user, cap.roles.items[2]);
+    try testing.expectEqual(conversation.MessageRole.assistant, cap.roles.items[3]);
 
-    // The display provider stamp rode through on every entry.
-    for (cap.providers.items) |p| {
-        try testing.expect(p != null);
-        try testing.expectEqualStrings("openai", p.?);
+    // The wire identity (base_url from the active config) rode through on
+    // every entry.
+    for (cap.base_urls.items) |b| {
+        try testing.expectEqualStrings("u", b);
     }
 }
 
@@ -1919,7 +1919,7 @@ test "agent runs a turn against NullStore without persisting or erroring" {
     h.activate();
 
     var ns = null_store_mod.NullStore.init(allocator);
-    var agent = Agent.init(allocator, io, &h.config, ns.store(), null);
+    var agent = Agent.init(allocator, io, &h.config, ns.store().create(), null);
     defer agent.deinit();
     h.seedInto(&agent);
     agent.open_stream_fn = stub.install();
@@ -2209,7 +2209,7 @@ test "runStep dispatches a tool call and loops to a final text turn" {
     try h.registry.register(try EchoTool.create(allocator, "echo", "ECHO:"));
     h.activate();
     var ns = null_store_mod.NullStore.init(allocator);
-    var agent = Agent.init(allocator, io, &h.config, ns.store(), null);
+    var agent = Agent.init(allocator, io, &h.config, ns.store().create(), null);
     defer agent.deinit();
     h.seedInto(&agent);
     agent.open_stream_fn = stub.install();
@@ -2260,7 +2260,7 @@ test "runStep dispatches multiple tool calls in parallel" {
     try h.registry.register(try BarrierTool.create(allocator, "barrierC", &barrier));
     h.activate();
     var ns = null_store_mod.NullStore.init(allocator);
-    var agent = Agent.init(allocator, io, &h.config, ns.store(), null);
+    var agent = Agent.init(allocator, io, &h.config, ns.store().create(), null);
     defer agent.deinit();
     h.seedInto(&agent);
     agent.open_stream_fn = stub.install();
@@ -2300,7 +2300,7 @@ test "runStep: native tool handler error becomes an error result and the model g
     try h.registry.register(try FailingTool.create(allocator, "boom"));
     h.activate();
     var ns = null_store_mod.NullStore.init(allocator);
-    var agent = Agent.init(allocator, io, &h.config, ns.store(), null);
+    var agent = Agent.init(allocator, io, &h.config, ns.store().create(), null);
     defer agent.deinit();
     h.seedInto(&agent);
     agent.open_stream_fn = stub.install();
@@ -2334,7 +2334,7 @@ test "runStep: unknown tool becomes an error tool result and the loop continues"
     defer h.deinit();
     h.activate();
     var ns = null_store_mod.NullStore.init(allocator);
-    var agent = Agent.init(allocator, io, &h.config, ns.store(), null);
+    var agent = Agent.init(allocator, io, &h.config, ns.store().create(), null);
     defer agent.deinit();
     h.seedInto(&agent);
     agent.open_stream_fn = stub.install();
@@ -2367,7 +2367,7 @@ test "runStep with no tool calls returns after one provider step" {
     defer h.deinit();
     h.activate();
     var ns = null_store_mod.NullStore.init(allocator);
-    var agent = Agent.init(allocator, io, &h.config, ns.store(), null);
+    var agent = Agent.init(allocator, io, &h.config, ns.store().create(), null);
     defer agent.deinit();
     h.seedInto(&agent);
     agent.open_stream_fn = stub.install();
@@ -2394,7 +2394,7 @@ test "runStep surfaces EmptyAssistantResponse when provider commits an empty mes
     defer h.deinit();
     h.activate();
     var ns = null_store_mod.NullStore.init(allocator);
-    var agent = Agent.init(allocator, io, &h.config, ns.store(), null);
+    var agent = Agent.init(allocator, io, &h.config, ns.store().create(), null);
     defer agent.deinit();
     h.seedInto(&agent);
     agent.open_stream_fn = stub.install();
@@ -2425,7 +2425,7 @@ test "runStep delivers all source-backed calls in one batch on one thread" {
     try h.registry.registerSource(try TestSource.create(allocator, "panto-lua", &.{ "lua_x", "lua_y" }));
     h.activate();
     var ns = null_store_mod.NullStore.init(allocator);
-    var agent = Agent.init(allocator, io, &h.config, ns.store(), null);
+    var agent = Agent.init(allocator, io, &h.config, ns.store().create(), null);
     defer agent.deinit();
     h.seedInto(&agent);
     agent.open_stream_fn = stub.install();
@@ -2477,7 +2477,7 @@ test "runStep: distinct sources run on distinct threads in parallel" {
     try h.registry.registerSource(try TestSource.create(allocator, "src_b", &.{"src_b_t"}));
     h.activate();
     var ns = null_store_mod.NullStore.init(allocator);
-    var agent = Agent.init(allocator, io, &h.config, ns.store(), null);
+    var agent = Agent.init(allocator, io, &h.config, ns.store().create(), null);
     defer agent.deinit();
     h.seedInto(&agent);
     agent.open_stream_fn = stub.install();
@@ -2515,7 +2515,7 @@ test "runStep: source whole-batch error becomes per-call error results and conti
     try h.registry.registerSource(try FailingSource.create(allocator, "fs", &.{ "fa", "fb" }));
     h.activate();
     var ns = null_store_mod.NullStore.init(allocator);
-    var agent = Agent.init(allocator, io, &h.config, ns.store(), null);
+    var agent = Agent.init(allocator, io, &h.config, ns.store().create(), null);
     defer agent.deinit();
     h.seedInto(&agent);
     agent.open_stream_fn = stub.install();
@@ -2559,7 +2559,7 @@ test "runStep: mixed single Tools and source-backed tools coexist in one turn" {
     try h.registry.registerSource(try TestSource.create(allocator, "src", &.{ "src_t1", "src_t2" }));
     h.activate();
     var ns = null_store_mod.NullStore.init(allocator);
-    var agent = Agent.init(allocator, io, &h.config, ns.store(), null);
+    var agent = Agent.init(allocator, io, &h.config, ns.store().create(), null);
     defer agent.deinit();
     h.seedInto(&agent);
     agent.open_stream_fn = stub.install();
@@ -2599,7 +2599,7 @@ test "setConfig swaps provider between turns; agent tool set persists" {
     };
 
     var ns = null_store_mod.NullStore.init(allocator);
-    var agent = Agent.init(allocator, io, &cfg_a, ns.store(), null);
+    var agent = Agent.init(allocator, io, &cfg_a, ns.store().create(), null);
     defer agent.deinit();
     try agent.registerTool(try EchoTool.create(allocator, "late", "B:"));
     agent.open_stream_fn = stub.install();
@@ -2638,7 +2638,7 @@ test "compact: summarizes prefix, keeps suffix, system survives" {
     // adding the longer first turn exceeds it.
     h.config.compaction = .{ .keep_verbatim = 10 };
     var ns = null_store_mod.NullStore.init(allocator);
-    var agent = Agent.init(allocator, io, &h.config, ns.store(), null);
+    var agent = Agent.init(allocator, io, &h.config, ns.store().create(), null);
     defer agent.deinit();
     h.seedInto(&agent);
     agent.open_stream_fn = stub.install();
@@ -2701,7 +2701,7 @@ test "compact: restated suffix usage reconstructs a fresh cumulative chain" {
     // summarizes the prefix.
     h.config.compaction = .{ .keep_verbatim = 20 };
     var ns = null_store_mod.NullStore.init(allocator);
-    var agent = Agent.init(allocator, io, &h.config, ns.store(), null);
+    var agent = Agent.init(allocator, io, &h.config, ns.store().create(), null);
     defer agent.deinit();
     h.seedInto(&agent);
     agent.open_stream_fn = stub.install();
@@ -2775,7 +2775,7 @@ test "compact: no-op when conversation already fits the budget" {
     h.activate();
     h.config.compaction = .{ .keep_verbatim = 1_000_000 };
     var ns = null_store_mod.NullStore.init(allocator);
-    var agent = Agent.init(allocator, io, &h.config, ns.store(), null);
+    var agent = Agent.init(allocator, io, &h.config, ns.store().create(), null);
     defer agent.deinit();
     h.seedInto(&agent);
     agent.open_stream_fn = stub.install();
@@ -2813,7 +2813,7 @@ test "compact: extra instructions are appended to the system prompt" {
     h.activate();
     h.config.compaction = .{ .keep_verbatim = 1 };
     var ns = null_store_mod.NullStore.init(allocator);
-    var agent = Agent.init(allocator, io, &h.config, ns.store(), null);
+    var agent = Agent.init(allocator, io, &h.config, ns.store().create(), null);
     defer agent.deinit();
     h.seedInto(&agent);
     agent.open_stream_fn = stub.install();
@@ -2854,7 +2854,7 @@ test "runStep: auto-compacts on context overflow and retries once" {
     h.activate();
     h.config.compaction = .{ .keep_verbatim = 10 };
     var ns = null_store_mod.NullStore.init(allocator);
-    var agent = Agent.init(allocator, io, &h.config, ns.store(), null);
+    var agent = Agent.init(allocator, io, &h.config, ns.store().create(), null);
     defer agent.deinit();
     h.seedInto(&agent);
     agent.open_stream_fn = stub.install();
@@ -2899,7 +2899,7 @@ test "runStep: context overflow without compaction prompt propagates" {
     defer h.deinit();
     h.activate();
     var ns = null_store_mod.NullStore.init(allocator);
-    var agent = Agent.init(allocator, io, &h.config, ns.store(), null);
+    var agent = Agent.init(allocator, io, &h.config, ns.store().create(), null);
     defer agent.deinit();
     h.seedInto(&agent);
     agent.open_stream_fn = stub.install();
@@ -2971,7 +2971,7 @@ test "runStep: provider 429 retries then succeeds without duplicate messages" {
     defer h.deinit();
     fastRetryHarness(&h);
     var ns = null_store_mod.NullStore.init(allocator);
-    var agent = Agent.init(allocator, io, &h.config, ns.store(), null);
+    var agent = Agent.init(allocator, io, &h.config, ns.store().create(), null);
     defer agent.deinit();
     h.seedInto(&agent);
     agent.open_stream_fn = stub.install();
@@ -3015,7 +3015,7 @@ test "runStep: provider 500 retries with backoff notification" {
     defer h.deinit();
     fastRetryHarness(&h);
     var ns = null_store_mod.NullStore.init(allocator);
-    var agent = Agent.init(allocator, io, &h.config, ns.store(), null);
+    var agent = Agent.init(allocator, io, &h.config, ns.store().create(), null);
     defer agent.deinit();
     h.seedInto(&agent);
     agent.open_stream_fn = stub.install();
@@ -3053,7 +3053,7 @@ test "runStep: provider auth failure does not retry" {
     defer h.deinit();
     fastRetryHarness(&h);
     var ns = null_store_mod.NullStore.init(allocator);
-    var agent = Agent.init(allocator, io, &h.config, ns.store(), null);
+    var agent = Agent.init(allocator, io, &h.config, ns.store().create(), null);
     defer agent.deinit();
     h.seedInto(&agent);
     agent.open_stream_fn = stub.install();
@@ -3092,7 +3092,7 @@ test "runStep: retries exhaust and hard-fail after max_attempts" {
     defer h.deinit();
     fastRetryHarness(&h);
     var ns = null_store_mod.NullStore.init(allocator);
-    var agent = Agent.init(allocator, io, &h.config, ns.store(), null);
+    var agent = Agent.init(allocator, io, &h.config, ns.store().create(), null);
     defer agent.deinit();
     h.seedInto(&agent);
     agent.open_stream_fn = stub.install();
@@ -3130,7 +3130,7 @@ test "runStep: Retry-After is honored and reported" {
     // Cap below the Retry-After to verify the policy cap applies.
     h.config.retry = .{ .initial_delay_ms = 0, .max_delay_ms = 1, .jitter = false };
     var ns = null_store_mod.NullStore.init(allocator);
-    var agent = Agent.init(allocator, io, &h.config, ns.store(), null);
+    var agent = Agent.init(allocator, io, &h.config, ns.store().create(), null);
     defer agent.deinit();
     h.seedInto(&agent);
     agent.open_stream_fn = stub.install();
@@ -3165,7 +3165,7 @@ test "runStep: cancellation from a tool still hard-fails" {
     try h.registry.register(try HardFailTool.create(allocator, "hard"));
     h.activate();
     var ns = null_store_mod.NullStore.init(allocator);
-    var agent = Agent.init(allocator, io, &h.config, ns.store(), null);
+    var agent = Agent.init(allocator, io, &h.config, ns.store().create(), null);
     defer agent.deinit();
     h.seedInto(&agent);
     agent.open_stream_fn = stub.install();
@@ -3196,7 +3196,7 @@ test "runStep: source per-call error produces a per-call error result and contin
     try h.registry.registerSource(try PartialSource.create(allocator, "ps", &.{ "pa", "pb" }));
     h.activate();
     var ns = null_store_mod.NullStore.init(allocator);
-    var agent = Agent.init(allocator, io, &h.config, ns.store(), null);
+    var agent = Agent.init(allocator, io, &h.config, ns.store().create(), null);
     defer agent.deinit();
     h.seedInto(&agent);
     agent.open_stream_fn = stub.install();
@@ -3235,7 +3235,7 @@ test "runStep: context-overflow compaction fires a compaction retry notification
     h.activate();
     h.config.compaction = .{ .keep_verbatim = 10 };
     var ns = null_store_mod.NullStore.init(allocator);
-    var agent = Agent.init(allocator, io, &h.config, ns.store(), null);
+    var agent = Agent.init(allocator, io, &h.config, ns.store().create(), null);
     defer agent.deinit();
     h.seedInto(&agent);
     agent.open_stream_fn = stub.install();