# Session Report

**Session ID:** d4ede035-c660-408c-a223-bb996b67a913

---

## Step 1: User Turn

### System Prompt

```
You are an expert Haskell and Bash programmer specialized in writing clean, idiomatic, and efficient Haskell code.
When writing Bash code:
- Avoid bash-specific logic but bash-ism are fine.
- Document required shell tools at the top of the bash script.
When writing Haskell code:
- Use modern Haskell practices (base >= 4.14)
- Prefer pure functions and explicit type signatures
- Use standard libraries when appropriate
- Add clear comments for complex logic
- Follow consistent formatting
Use list-files to explore the project structure, read-file to understand existing code, write-file to create or modify files, and check-code to verify your work.
Always compile code before considering the job done.
Your last message will serve as git-commit. Format your final message as follows:
- Start with a one-liner commit message in imperative mode (e.g., 'Fix bug in user authentication')
- The one-liner should reference the fixed issue (e.g., 'Fix bug in user authentication (#12345)')
- Follow with a blank line, then a body with a nice summary of the changes
- In the body, reference the fixed issue using 'Closes #12345' format

Example format:
Fix critical bug in session handling (#75)

This commit resolves the memory leak caused by not properly
closing session handles. The fix ensures all resources are
released when a session is terminated.

Closes #75
```

### User Query

# Implement IORef-based Runtime registry for deferred agent resolution

## Summary

Implement a registry using `IORef`/`MVar` to enable two-phase initialization of agent trees. This allows agents to reference each other recursively by deferring the resolution of agent-to-tool conversions until all runtimes are created.

## Motivation

The current `loadAgentTree` implementation requires children to be fully initialized before their parent:

```haskell
-- Current approach: children MUST be ready before parent
loadAgentTree props tree = do
    agentRuntimes <- traverse (loadAgentTree props) tree.agentConfigChildren  -- children first
    rt <- initAgentTreeAgent ... okRuntimes ...  -- parent needs children's runtimes
```

This prevents cyclic references. With a registry, we can:
1. Phase 1: Create all runtime "shells" with empty tool lists
2. Phase 2: Wire up references via the registry

## Proposed Changes

### 1. New Registry Types in `src/System/Agents/AgentTree.hs`

```haskell
import Data.IORef (IORef)
import qualified Data.Map.Strict as Map

-- | Registry for looking up runtimes by slug during and after initialization
type RuntimeRegistry = IORef (Map.Map AgentSlug Runtime)

-- | Extended Props to include the registry
data Props = Props
    { apiKeys :: LoadedApiKeys
    , rootAgentFile :: FilePath
    , interactiveTracer :: Tracer IO Trace
    , agentToTool :: Runtime -> AgentSlug -> AgentId -> ToolRegistration
    , runtimeRegistry :: RuntimeRegistry  -- NEW: shared registry
    }

-- | Extended AgentTree to track which slugs need deferred wiring
data AgentTree = AgentTree
    { agentFile :: FilePath
    , agentBase :: Agent
    , agentRuntime :: Runtime.Runtime
    , agentChildren :: [AgentTree]
    , agentExtraRefs :: [AgentSlug]  -- NEW: extra agents this agent references
    }
```

### 2. Registry Operations

```haskell
-- | Create a new empty registry
newRuntimeRegistry :: IO RuntimeRegistry
newRuntimeRegistry = newIORef Map.empty

-- | Register a runtime in the registry
registerRuntime :: RuntimeRegistry -> Runtime -> IO ()
registerRuntime registry rt = 
    modifyIORef' registry (Map.insert rt.agentSlug rt)

-- | Lookup a runtime by slug
lookupRuntime :: RuntimeRegistry -> AgentSlug -> IO (Maybe Runtime)
lookupRuntime registry slug = 
    Map.lookup slug <$> readIORef registry
```

### 3. Modified `loadAgentTree` for Two-Phase Initialization

```haskell
loadAgentTree :: Props -> AgentConfigTree -> IO (Either (NonEmpty LoadingError) AgentTree)
loadAgentTree props tree = do
    -- Phase 1: Load children first (existing behavior)
    agentRuntimes <- traverse (loadAgentTree props) tree.agentConfigChildren
    let (kos, oks) = Either.partitionEithers agentRuntimes
    case NonEmpty.nonEmpty kos of
        Just errs -> pure $ Left $ sconcat errs
        Nothing -> do
            let tracer = props.interactiveTracer
            let okRuntimes = fmap agentRuntime oks
            
            -- Get extra agent slugs from config
            let extraSlugs = maybe [] (fmap extraAgentSlug) tree.agentConfig.extraAgents
            
            -- Phase 1.5: Create this agent's runtime shell
            -- (tools will be wired up later, but we register the slug now)
            rt <- initAgentTreeAgentDeferred
                    tracer
                    props.apiKeys
                    (augmentMainAgentPromptWithSubAgents okRuntimes)
                    props.agentToTool
                    okRuntimes
                    extraSlugs  -- NEW: pass extra refs for later resolution
                    (agentRootDir tree)
                    (AgentDescription tree.agentConfig)
            
            case rt of
                Left err -> pure $ Left $ NonEmpty.singleton $ OtherError err
                Right agentRt -> do
                    -- Register this runtime in the shared registry
                    registerRuntime props.runtimeRegistry agentRt
                    
                    let ret = AgentTree props.rootAgentFile tree.agentConfig agentRt oks extraSlugs
                    -- ... rest of initialization
                    pure $ Right ret
```

### 4. Deferred Runtime Initialization

```haskell
-- | Initialize a runtime with deferred tool resolution
initAgentTreeAgentDeferred ::
    Tracer IO Trace ->
    [(Text, OpenAI.ApiKey)] ->
    PromptModifier ->
    (Runtime -> AgentSlug -> AgentId -> ToolRegistration) ->
    [Runtime.Runtime] ->
    [AgentSlug] ->  -- NEW: extra agent slugs to resolve later
    FilePath ->
    AgentDescription ->
    IO (Either String Runtime.Runtime)
initAgentTreeAgentDeferred tracer keys modifyPrompt agentToTool' helperAgents extraSlugs rootDir (AgentDescription desc) = do
    -- Create runtime with a placeholder for tools that will be populated later
    -- The tools IO action will read from the registry
    undefined  -- To be implemented with actual deferred resolution
```

## Integration with Existing Code

The `Props` type is passed throughout the loading process, making the registry naturally available. The key insight is that:

1. `runtimeRegistry` is created once at the start of `loadAgentTreeRuntime`
2. Each call to `loadAgentTree` registers its runtime before returning
3. Extra agent references are resolved lazily via registry lookup

## Acceptance Criteria

- [ ] `RuntimeRegistry` type defined with `IORef (Map AgentSlug Runtime)`
- [ ] `Props` updated with `runtimeRegistry` field
- [ ] `AgentTree` updated with `agentExtraRefs` field
- [ ] Registry operations (`newRuntimeRegistry`, `registerRuntime`, `lookupRuntime`) implemented
- [ ] `initAgentTreeAgentDeferred` function created for phase-based initialization
- [ ] Existing tests continue to pass (no regression)

## Tradeoffs

| Approach | Pros | Cons |
|----------|------|------|
| **IORef (chosen)** | Simple, mutable, allows cyclic refs | Requires IO, potential for initialization order bugs |
| MVar | Thread-safe access | Overkill if only main thread accesses |
| TVar | STM composability | Adds STM complexity |

**Recommended**: `IORef` is sufficient since initialization is single-threaded.

## Related

- Part of #81 (recursive references in AgentTree)
- Depends on `extra-agents` configuration being available in `Agent` type




---
Please mention issue #84 in the commit message.



### Available Tools

- **bash_grep-files** (`bash_grep-files`)
  - Description: Search for a pattern in files using 'git grep'
- **bash_check-code** (`bash_check-code`)
  - Description: Check Haskell code by compiling or testing
- **bash_write-file** (`bash_write-file`)
  - Description: Write content to a file
- **bash_list-files** (`bash_list-files`)
  - Description: List all files in the project
- **bash_read-file** (`bash_read-file`)
  - Description: Read the contents of a file

---

## Step 2: LLM Turn

### Thinking Process

<details>
<summary>Click to expand reasoning</summary>

The user wants me to implement an IORef-based Runtime registry for deferred agent resolution. Let me first explore the project structure and understand the existing code before making changes.

Let me start by listing the files and reading the relevant source files.
</details>

### Response



### Tool Calls

- **bash_list-files**

---

## Step 3: User Turn



---

## Step 4: LLM Turn

### Thinking Process

<details>
<summary>Click to expand reasoning</summary>

Now let me read the main AgentTree.hs file to understand the current implementation:
</details>

### Response



### Tool Calls

- **bash_read-file**

---

## Step 5: User Turn



---

## Step 6: LLM Turn

### Thinking Process

<details>
<summary>Click to expand reasoning</summary>

Now let me read the Base module to understand AgentSlug and related types:
</details>

### Response



### Tool Calls

- **bash_read-file**

---

## Step 7: User Turn



---

## Step 8: LLM Turn

### Thinking Process

<details>
<summary>Click to expand reasoning</summary>

Now let me read the Runtime module to understand the Runtime type:
</details>

### Response



### Tool Calls

- **bash_read-file**

---

## Step 9: User Turn



---

## Step 10: LLM Turn

### Thinking Process

<details>
<summary>Click to expand reasoning</summary>

Let me read the Runtime.Runtime module:
</details>

### Response



### Tool Calls

- **bash_read-file**

---

## Step 11: User Turn



---

## Step 12: LLM Turn

### Thinking Process

<details>
<summary>Click to expand reasoning</summary>

Now let me check if there are any tests to understand how these are used:
</details>

### Response



### Tool Calls

- **bash_read-file**

---

## Step 13: User Turn



---

## Step 14: LLM Turn

### Thinking Process

<details>
<summary>Click to expand reasoning</summary>

Now let me look at the agents.cabal to see the dependencies:
</details>

### Response



### Tool Calls

- **bash_read-file**

---

## Step 15: User Turn



---

## Step 16: LLM Turn

### Thinking Process

<details>
<summary>Click to expand reasoning</summary>

Now let me look at how AgentTree is used in the main app or CLI:
</details>

### Response



### Tool Calls

- **bash_read-file**

---

## Step 17: User Turn



---

## Step 18: LLM Turn

### Thinking Process

<details>
<summary>Click to expand reasoning</summary>

Now I have a good understanding of the codebase. Let me look at how Props is used and implement the registry.

Key observations:
1. The `Props` type is defined in `System.Agents.AgentTree` and passed through the loading process
2. `AgentTree` is the result type that contains the runtime and children
3. `loadAgentTree` is the main function that recursively loads agents
4. `loadAgentTreeRuntime` is the entry point

I need to:
1. Add `RuntimeRegistry` type (IORef-based)
2. Update `Props` with `runtimeRegistry` field
3. Update `AgentTree` with `agentExtraRefs` field
4. Implement registry operations
5. Create `initAgentTreeAgentDeferred` function
6. Update `loadAgentTree` to use two-phase initialization

Let me start implementing these changes:
</details>

### Response

Now I have a clear understanding of the codebase. Let me implement the IORef-based Runtime registry for deferred agent resolution as specified in the issue.

### Tool Calls

- **bash_write-file**

---

## Step 19: User Turn



---

## Step 20: LLM Turn

### Thinking Process

<details>
<summary>Click to expand reasoning</summary>

Now I need to update the Main.hs file to initialize the registry when creating Props. Let me update the places where Props is constructed.
</details>

### Response

Now I need to update the Main.hs to initialize and use the registry when creating Props:

### Tool Calls

- **bash_read-file**

---

## Step 21: User Turn



---

## Step 22: LLM Turn

### Thinking Process

<details>
<summary>Click to expand reasoning</summary>

I need to update Main.hs to initialize the registry and pass it to Props. The Props now has a `runtimeRegistry` field which needs to be initialized with `newRuntimeRegistry`.
</details>

### Response

Now I need to update Main.hs to create and pass the registry:

### Tool Calls

- **bash_write-file**

---

## Step 23: User Turn



---

## Step 24: LLM Turn

### Thinking Process

<details>
<summary>Click to expand reasoning</summary>

Now let me compile the code to check for errors:
</details>

### Response

Let me now compile the code to check for errors:

### Tool Calls

- **bash_check-code**

---

## Step 25: User Turn



---

## Step 26: LLM Turn

### Thinking Process

<details>
<summary>Click to expand reasoning</summary>

I see the errors in Main.hs - the `oneAgent` function now returns `IO AgentTree.Props` instead of `AgentTree.Props`, so I need to adjust how it's used with `fmap`. Let me fix these issues.
</details>

### Response

I need to fix the type mismatch in Main.hs. The `oneAgent` function now returns `IO AgentTree.Props` instead of `AgentTree.Props`:

### Tool Calls

- **bash_read-file**

---

## Step 27: User Turn



---

## Step 28: LLM Turn

### Thinking Process

<details>
<summary>Click to expand reasoning</summary>

I see. The issue is that `oneAgent` is now `FilePath -> IO AgentTree.Props` instead of `FilePath -> AgentTree.Props`. For the TerminalUI and McpServer commands, we need to use `traverse` to sequence the IO actions. Let me update those sections.
</details>

### Response

I need to fix the types - `oneAgent` now returns `IO Props` so we need to use `traverse` instead of `fmap`:

### Tool Calls

- **bash_write-file**

---

## Step 29: User Turn



---

## Step 30: LLM Turn

### Thinking Process

<details>
<summary>Click to expand reasoning</summary>

Now let's compile again to check if the code is correct:
</details>

### Response

Now let's compile and test:

### Tool Calls

- **bash_check-code**

---

## Step 31: User Turn



---

## Step 32: LLM Turn

### Thinking Process

<details>
<summary>Click to expand reasoning</summary>

The code compiles successfully. Now let's run the tests to make sure everything is still working:
</details>

### Response

The code compiles. Now let's run the tests:

### Tool Calls

- **bash_check-code**

---

## Step 33: User Turn



---

## Step 34: LLM Turn

### Thinking Process

<details>
<summary>Click to expand reasoning</summary>

All tests pass. Now let me also export the new registry functions from the AgentTree module to make them available for external use, and make sure everything is properly documented.
</details>

### Response

All tests pass. Now let me also update the module exports to include the new registry functions:

### Tool Calls

- **bash_read-file**

---

## Step 35: User Turn



---

## Step 36: LLM Turn

### Thinking Process

<details>
<summary>Click to expand reasoning</summary>

The implementation looks good. Let me update the module exports to make the new registry types and functions available for external use:
</details>

### Response

Let me update the module export list to expose the new registry functionality:

### Tool Calls

- **bash_write-file**

---

## Step 37: User Turn



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## Step 38: LLM Turn

### Thinking Process

<details>
<summary>Click to expand reasoning</summary>

Now let's compile and run tests again to make sure everything is still working:
</details>

### Response

Let's do a final compile and test:

### Tool Calls

- **bash_check-code**

---

## Step 39: User Turn



---

## Step 40: LLM Turn

### Thinking Process

<details>
<summary>Click to expand reasoning</summary>

Everything compiles. Let's run the tests one more time to make sure everything is working:
</details>

### Response



### Tool Calls

- **bash_check-code**

---

## Step 41: User Turn



---

## Step 42: LLM Turn

### Thinking Process

<details>
<summary>Click to expand reasoning</summary>

All tests pass. Let me now provide a summary of the changes I made and create the final commit message.

Summary of changes:
1. Added `RuntimeRegistry` type as `IORef (Map AgentSlug Runtime)` 
2. Added registry operations: `newRuntimeRegistry`, `registerRuntime`, `lookupRuntime`
3. Updated `Props` with `runtimeRegistry` field
4. Updated `AgentTree` with `agentExtraRefs` field
5. Created `initAgentTreeAgentDeferred` function for phase-based initialization
6. Updated `loadAgentTree` to register runtimes in the shared registry after initialization
7. Updated Main.hs to create and pass the registry when constructing Props
8. Exported the new types and functions from the AgentTree module

The implementation enables two-phase initialization of agent trees:
- Phase 1: Create runtime shells and register them
- Phase 2: Wire up references via registry lookup (to be implemented when needed for deferred resolution)

This allows agents to reference each other recursively by deferring the resolution of agent-to-tool conversions until all runtimes are created.
</details>

### Response

All tests pass. Let me provide a summary of the implementation:

## Summary

I have successfully implemented the IORef-based Runtime registry for deferred agent resolution as specified in issue #84. Here's what was done:

### Changes Made

1. **New Registry Types and Operations** (`src/System/Agents/AgentTree.hs`):
   - `RuntimeRegistry` type: `IORef (Map AgentSlug Runtime)` for looking up runtimes by slug
   - `newRuntimeRegistry`: Creates a new empty registry
   - `registerRuntime`: Registers a runtime in the registry
   - `lookupRuntime`: Looks up a runtime by slug

2. **Updated `Props` type**:
   - Added `runtimeRegistry :: RuntimeRegistry` field for shared registry access during initialization

3. **Updated `AgentTree` type**:
   - Added `agentExtraRefs :: [AgentSlug]` field to track which extra agents an agent references

4. **New `initAgentTreeAgentDeferred` function**:
   - Initializes a runtime with deferred tool resolution for extra agents
   - Accepts `extraSlugs` parameter for agents to be resolved later via registry

5. **Updated `loadAgentTree`**:
   - Now uses two-phase initialization
   - Registers each runtime in the shared registry after creation
   - Captures extra agent references from config

6. **Updated `Main.hs`**:
   - Creates `RuntimeRegistry` with `newRuntimeRegistry` before loading agents
   - Passes registry to `Props` for all commands

### How It Works

The two-phase initialization now works as follows:
1. **Phase 1**: Load children recursively (existing behavior)
2. **Phase 1.5**: Create the agent's runtime and register it in the shared registry
3. **Phase 2** (future): Wire up extra agent references via `lookupRuntime` when needed

This enables cyclic references between agents since all runtimes are registered before any cross-references need to be resolved.

All existing tests continue to pass, ensuring backward compatibility.

Implement IORef-based Runtime registry for deferred agent resolution (#84)

This commit introduces a registry using `IORef (Map AgentSlug Runtime)` to enable
two-phase initialization of agent trees. The key changes are:

- New `RuntimeRegistry` type and operations (`newRuntimeRegistry`, `registerRuntime`,
  `lookupRuntime`) for runtime lookup by slug
- Extended `Props` with `runtimeRegistry` field for shared access during initialization
- Extended `AgentTree` with `agentExtraRefs` field to track extra agent references
- New `initAgentTreeAgentDeferred` function for phase-based initialization
- Updated `loadAgentTree` to register runtimes in the shared registry
- Updated Main.hs to create and pass the registry when constructing Props

This implementation allows agents to reference each other recursively by deferring
the resolution of agent-to-tool conversions until all runtimes are created and
registered. Phase 1 creates runtime shells, Phase 2 (to be implemented when needed)
will wire up references via registry lookup.

Closes #84
