proxy: support user defined metadata in model configuration

CLAUDE.md

@@ -0,0 +1,43 @@
+# Project: llama-swap
+
+## Project Description:
+
+llama-swap is a light weight, transparent proxy server that provides automatic model swapping to llama.cpp's server.
+
+## Tech stack
+
+- golang
+- typescript, vite and react for UI (ui/)
+
+## Testing
+
+- `make test-dev` - Use this when making iterative changes. Runs `go test` and `staticcheck`. Fix any static checking errors.
+- `make test-all` - runs at the end before completing work. Includes long running concurrency tests.
+
+## Workflow Tasks
+
+### Plan Improvements
+
+Work plans are located in ai-plans/. Plans written by the user may be incomplete, contain inconsistencies or errors.
+
+When the user asks to improve a plan follow these guidelines for expanding and improving it.
+
+- Identify any inconsistencies.
+- Expand plans out to be detailed specification of requirements and changes to be made.
+- Plans should have at least these sections:
+  - Title - very short, describes changes
+  - Overview: A more detailed summary of goal and outcomes desired
+  - Design Requirements: Detailed descriptions of what needs to be done
+  - Testing Plan: Tests to be implemented
+  - Checklist: A detailed list of changes to be made
+
+Look for "plan expansion" as explicit instructions to improve a plan.
+
+### Implementation of plans
+
+When the user says "paint it", respond with "commencing automated assembly". Then implement the changes as described by the plan. Update the checklist as you complete items.
+
+## General Rules
+
+- when summarizing changes only include details that require further action (action items)
+- when there are no action items, just say "Done."

Makefile

@@ -23,6 +23,11 @@ proxy/ui_dist/placeholder.txt:
 	mkdir -p proxy/ui_dist
 	touch $@
 
+# use cached test results while developing
+test-dev: proxy/ui_dist/placeholder.txt
+	go test -short ./proxy/...
+	staticcheck ./proxy/... || true
+
 test: proxy/ui_dist/placeholder.txt
 	go test -short -count=1 ./proxy/...
 
@@ -82,4 +87,4 @@ release:
 	git tag "$$new_tag";
 
 # Phony targets
-.PHONY: all clean ui mac linux windows simple-responder test test-all
+.PHONY: all clean ui mac linux windows simple-responder test test-all test-dev

ai-plans/issue-264-add-metadata.md

@@ -0,0 +1,292 @@
+# Add Model Metadata Support with Typed Macros
+
+## Overview
+
+Implement support for arbitrary metadata on model configurations that can be exposed through the `/v1/models` API endpoint. This feature extends the existing macro system to support scalar types (string, int, float, bool) instead of only strings, enabling type-safe metadata values.
+
+The metadata will be schemaless, allowing users to define any key-value pairs they need. Macro substitution will work within metadata values, preserving types when macros are used directly and converting to strings when macros are interpolated within strings.
+
+## Design Requirements
+
+### 1. Enhanced Macro System
+
+**Current State:**
+
+- Macros are defined as `map[string]string` at both global and model levels
+- Only string substitution is supported
+- Macros are replaced in: `cmd`, `cmdStop`, `proxy`, `checkEndpoint`, `filters.stripParams`
+
+**Required Changes:**
+
+- Change `MacroList` type from `map[string]string` to `map[string]any`
+- Support scalar types: `string`, `int`, `float64`, `bool`
+- Implement type-preserving macro substitution:
+  - Direct macro usage (`key: ${macro}`) preserves the macro's type
+  - Interpolated usage (`key: "text ${macro}"`) converts to string
+- Add validation to ensure macro values are scalar types only
+- Update existing macro substitution logic in [proxy/config/config.go](proxy/config/config.go) to handle `any` types
+
+**Implementation Details:**
+
+- Create a generic helper function to perform macro substitution that:
+  - Takes a value of type `any`
+  - Recursively processes maps, slices, and scalar values
+  - Replaces `${macro_name}` patterns with macro values
+  - Preserves types for direct substitution
+  - Converts to strings for interpolated substitution
+- Update `validateMacro()` function to accept `any` type and validate scalar types
+- Maintain backward compatibility with existing string-only macros
+
+### 2. Metadata Field in ModelConfig
+
+**Location:** [proxy/config/model_config.go](proxy/config/model_config.go)
+
+**Required Changes:**
+
+- Add `Metadata map[string]any` field to `ModelConfig` struct
+- Support YAML unmarshaling of arbitrary structures (maps, arrays, scalars)
+- Apply macro substitution to metadata values during config loading
+
+**Schema Requirements:**
+
+- Metadata is optional (default: empty/nil map)
+- Supports nested structures (objects within objects, arrays, etc.)
+- All string values within metadata undergo macro substitution
+- Type preservation rules apply as described above
+
+### 3. Macro Substitution in Metadata
+
+**Location:** [proxy/config/config.go](proxy/config/config.go) in `LoadConfigFromReader()`
+
+**Process Flow:**
+
+1. After loading YAML configuration
+2. After model-level and global macro merging
+3. Apply macro substitution to `ModelConfig.Metadata` field
+4. Use the same merged macros available to `cmd`, `proxy`, etc.
+5. Process recursively through all nested structures
+
+**Substitution Rules:**
+
+- `port: ${PORT}` → keeps integer type from PORT macro
+- `temperature: ${temp}` → keeps float type from temp macro
+- `note: "Running on ${PORT}"` → converts to string `"Running on 10001"`
+- Arrays and nested objects are processed recursively
+- Unknown macros should cause configuration load error (consistent with existing behavior)
+
+### 4. API Response Updates
+
+**Location:** [proxy/proxymanager.go:350](proxy/proxymanager.go#L350) `listModelsHandler()`
+
+**Current Behavior:**
+
+- Returns model records with: `id`, `object`, `created`, `owned_by`
+- Optionally includes: `name`, `description`
+
+**Required Changes:**
+
+- Add metadata to each model record under the key `llamaswap_meta`
+- Only include `llamaswap_meta` if metadata is non-empty
+- Preserve all types when marshaling to JSON
+- Maintain existing sorting by model ID
+
+**Example Response:**
+
+```json
+{
+  "object": "list",
+  "data": [
+    {
+      "id": "llama",
+      "object": "model",
+      "created": 1234567890,
+      "owned_by": "llama-swap",
+      "name": "llama 3.1 8B",
+      "description": "A small but capable model",
+      "llamaswap_meta": {
+        "port": 10001,
+        "temperature": 0.7,
+        "note": "The llama is running on port 10001 temp=0.7, context=16384",
+        "a_list": [1, 1.23, "macros are OK in list and dictionary types: llama"],
+        "an_obj": {
+          "a": "1",
+          "b": 2,
+          "c": [0.7, false, "model: llama"]
+        }
+      }
+    }
+  ]
+}
+```
+
+### 5. Validation and Error Handling
+
+**Macro Validation:**
+
+- Extend `validateMacro()` to accept values of type `any`
+- Verify macro values are scalar types: `string`, `int`, `float64`, `bool`
+- Reject complex types (maps, slices, structs) as macro values
+- Maintain existing validation for macro names and lengths
+
+**Configuration Loading:**
+
+- Fail fast if unknown macros are found in metadata
+- Provide clear error messages indicating which model and field contains errors
+- Ensure macros in metadata follow same rules as macros in cmd/proxy fields
+
+## Testing Plan
+
+### Test 1: Model-Level Macros with Different Types
+
+**File:** [proxy/config/model_config_test.go](proxy/config/model_config_test.go)
+
+**Test Cases:**
+
+- Define model with macros of each scalar type
+- Verify metadata correctly substitutes and preserves types
+- Test direct substitution (`port: ${PORT}`)
+- Test string interpolation (`note: "Port is ${PORT}"`)
+- Verify nested objects and arrays work correctly
+
+### Test 2: Global and Model Macro Precedence
+
+**File:** [proxy/config/config_test.go](proxy/config/config_test.go)
+
+**Test Cases:**
+
+- Define same macro at global and model level with different types
+- Verify model-level macro takes precedence
+- Test metadata uses correct macro value
+- Verify type is preserved from the winning macro
+
+### Test 3: Macro Validation
+
+**File:** [proxy/config/config_test.go](proxy/config/config_test.go)
+
+**Test Cases:**
+
+- Test that complex types (maps, arrays) are rejected as macro values
+  - Verify error message includes: macro name and type that was rejected
+- Test that scalar types (string, int, float, bool) are accepted
+  - Each type should load without error
+- Test macro name validation still works with `any` types
+  - Invalid characters, reserved names, length limits should still be enforced
+
+### Test 4: Metadata in API Response
+
+**File:** [proxy/proxymanager_test.go](proxy/proxymanager_test.go)
+
+**Existing Test:** `TestProxyManager_ListModelsHandler`
+
+**Test Cases:**
+
+- Model with metadata → verify `llamaswap_meta` key appears
+- Model without metadata → verify `llamaswap_meta` key is absent
+- Verify all types are correctly marshaled to JSON
+- Verify nested structures are preserved
+- Verify macro substitution has occurred before serialization
+
+### Test 5: Unknown Macros in Metadata
+
+**File:** [proxy/config/config_test.go](proxy/config/config_test.go)
+
+**Test Cases:**
+
+- Use undefined macro in metadata
+- Verify configuration loading fails with clear error
+- Error should indicate model name and that macro is undefined
+
+### Test 6: Recursive Substitution
+
+**File:** [proxy/config/config_test.go](proxy/config/config_test.go)
+
+**Test Cases:**
+
+- Metadata with deeply nested structures
+- Arrays containing objects with macros
+- Objects containing arrays with macros
+- Mixed string interpolation and direct substitution at various nesting levels
+
+## Checklist
+
+### Configuration Schema Changes
+
+- [x] Change `MacroList` type from `map[string]string` to `map[string]any` in [proxy/config/config.go:19](proxy/config/config.go#L19)
+- [x] Add `Metadata map[string]any` field to `ModelConfig` struct in [proxy/config/model_config.go:37](proxy/config/model_config.go#L37)
+- [x] Update `validateMacro()` function signature to accept `any` type for values
+- [x] Add validation logic to ensure macro values are scalar types only
+
+### Macro Substitution Logic
+
+- [x] Create generic recursive function `substituteMetadataMacros()` to handle `any` types
+- [x] Implement type-preserving direct substitution logic
+- [x] Implement string interpolation with type conversion
+- [x] Handle maps: recursively process all values
+- [x] Handle slices: recursively process all elements
+- [x] Handle scalar types: perform string-based macro substitution if value is string
+- [x] Integrate macro substitution into `LoadConfigFromReader()` after existing macro expansion
+- [x] Update existing macro substitution calls to use merged macros with correct types
+
+### API Response Changes
+
+- [x] Modify `listModelsHandler()` in [proxy/proxymanager.go:350](proxy/proxymanager.go#L350)
+- [x] Add `llamaswap_meta` field to model records when metadata exists
+- [x] Ensure empty metadata results in omitted `llamaswap_meta` key
+- [x] Verify JSON marshaling preserves all types correctly
+
+### Testing - Config Package
+
+- [x] Add test for string macros in metadata: [proxy/config/config_test.go](proxy/config/config_test.go)
+- [x] Add test for int macros in metadata: [proxy/config/config_test.go](proxy/config/config_test.go)
+- [x] Add test for float macros in metadata: [proxy/config/config_test.go](proxy/config/config_test.go)
+- [x] Add test for bool macros in metadata: [proxy/config/config_test.go](proxy/config/config_test.go)
+- [x] Add test for string interpolation in metadata: [proxy/config/config_test.go](proxy/config/config_test.go)
+- [x] Add test for model-level macro precedence: [proxy/config/config_test.go](proxy/config/config_test.go)
+- [x] Add test for nested structures in metadata: [proxy/config/config_test.go](proxy/config/config_test.go)
+- [x] Add test for unknown macro in metadata (should error): [proxy/config/config_test.go](proxy/config/config_test.go)
+- [x] Add test for invalid macro type validation: [proxy/config/config_test.go](proxy/config/config_test.go)
+
+### Testing - Model Config Package
+
+- [x] Add test cases to [proxy/config/model_config_test.go](proxy/config/model_config_test.go) for metadata unmarshaling
+- [x] Test metadata with various scalar types
+- [x] Test metadata with nested objects and arrays
+
+### Testing - Proxy Manager
+
+- [x] Update `TestProxyManager_ListModelsHandler` in [proxy/proxymanager_test.go](proxy/proxymanager_test.go)
+- [x] Add test case for model with metadata
+- [x] Add test case for model without metadata
+- [x] Verify `llamaswap_meta` key presence/absence
+- [x] Verify type preservation in JSON output
+- [x] Verify macro substitution has occurred
+
+### Documentation
+
+- [x] Verify [config.example.yaml](config.example.yaml) already has complete metadata examples (lines 149-171)
+- [x] No additional documentation needed per project instructions
+
+## Known Issues and Considerations
+
+### Inconsistencies
+
+None identified. The plan references the correct existing example in [config.example.yaml:149-171](config.example.yaml#L149-L171).
+
+### Design Decisions
+
+1. **Why `llamaswap_meta` instead of merging into record?**
+
+   - Avoids potential collisions with OpenAI API standard fields
+   - Makes it clear this is llama-swap specific metadata
+   - Easier for clients to distinguish standard vs. custom fields
+
+2. **Why support nested structures?**
+
+   - Provides maximum flexibility for users
+   - Aligns with the schemaless design principle
+   - Example config already demonstrates this capability
+
+3. **Why validate macro types?**
+   - Prevents confusing behavior (e.g., substituting a map)
+   - Makes configuration errors explicit at load time
+   - Simpler implementation and testing