diff --git a/.github/workflows/docs.yaml b/.github/workflows/docs.yaml
index 22590f0..689af14 100644
--- a/.github/workflows/docs.yaml
+++ b/.github/workflows/docs.yaml
@@ -24,7 +24,9 @@ jobs:
           pip install mkdocs
 
       - name: Build MkDocs site
-        run: mkdocs build --clean
+        run: |
+          mkdocs build --clean
+          echo 'docs.metaprompt-lang.org' > ./site/CNAME
 
       - name: Deploy to GitHub Pages
         uses: peaceiris/actions-gh-pages@v3
diff --git a/README.md b/README.md
index cc97410..4238983 100644
--- a/README.md
+++ b/README.md
@@ -56,7 +56,6 @@ This is an early work-in-progress. Follow [me on twitter](https://x.com/klntsky)
   - [x] `[:if ... :then ... :else ...]`
   - [x] `[$ meta-prompt]`
   - [x] `[:use module :param1=value1]`
-  - [ ] `[:model model-id ...]` for dynamic model selection
   - [x] `[# comments]`
   - [ ] `[:status some-status]` - to show during prompt evaluation
   - [ ] `[:call ffi-function :param1=foo :param2=bar]`
@@ -69,28 +68,53 @@ This is an early work-in-progress. Follow [me on twitter](https://x.com/klntsky)
     - [x] OpenAI
     - [ ] Anthropic
     - [ ] llama
-  - [ ] dynamic model switching
 - [ ] Runtime system
   - [x] Support variable definition at runtime
+  - [x] dynamic model switching (via `MODEL` variable - [example](./python/examples/model-change.metaprompt))
   - [ ] exceptions
     - [ ] throwing exceptions
     - [ ] recovering from exceptions
+  - [ ] LLM output validation?
+    - [ ] via regexps?
+    - [ ] via parsing?
 - [ ] FFI
-  - [ ] syntax
+  - [ ] syntax - preferably via `[:use @ffi-function :param1=foo :param2=bar]`
+  - [ ] how to throw exceptions from FFI
   - [ ] API
   - [ ] standard library
+    - [ ] text processing
+    - [ ] shell access
+    - [ ] running executables
+    - [ ] file system access
+      - [ ] isolation?
+    - [ ] HTTP stack
 - Utils
-  - [x] Unbound variable auto discovery to turn metaprompts into interfaces
+  - [x] Unbound variable auto discovery
+  - [ ] Machinery to turn metaprompts into interfaces (parameters become form fields)
+    - [ ] static validation?
 - [ ] Add function definitions
   - [ ] enable function scopes
 - [ ] Add a module system
   - [x] syntax
-  - [x] runtime
+  - [x] module loading at runtime
+  - [ ] preload modules on startup - is needed?
+  - [ ] module caching
   - [ ] tests
 - [ ] Add a package system
   - [ ] specify package format
   - [ ] create a package registry
-  - [ ] package installer
+  - [ ] on-the-fly package installer
+
+## Architecture decisions
+
+- functions, files, and modules are essentially the same - invoked with `[:use ...]`
+- metaprompt parameters are just variables that are not bound before first use - this and the above decision allow to get rid of function syntax entirely
+
+### To consider
+
+- dynamic module loading vs. static module loading: dynamic is lazy, so skips unneeded modules, but static loading guarantees absence of runtime errors due to module resultion failures (which saves costs)
+- exception system. how to pass payloads with exceptions
+- turning exceptions into continuations in spirit of [hurl](https://hurl.wtf)
 
 ## Notable sources of inspiration
 
diff --git a/python/src/loader.py b/python/src/loader.py
index 7567c4b..e2d9863 100644
--- a/python/src/loader.py
+++ b/python/src/loader.py
@@ -4,6 +4,10 @@ def _discover_variables(ast):
             yield from _discover_variables(node)
     elif isinstance(ast, dict):
         if "type" in ast:
+            # TODO: evaluate both :if branches in parallel, to cover this case:
+            # [:if foo :then [:bar=baz] :else [:bar]]
+            #  -- [:bar] should be unbound here, because it is unbound in the
+            # first branch
             if ast["type"] == "comment":
                 return
             elif ast["type"] == "var":
diff --git a/python/src/main.py b/python/src/main.py
index b3b9929..7e2d668 100644
--- a/python/src/main.py
+++ b/python/src/main.py
@@ -37,10 +37,14 @@ def parse_arguments():
         "--model",
         type=str,
         help="LLM id to use",
-        default="interactive" # TODO: use dynamic model selection
+        default="interactive",  # TODO: use dynamic model selection
     )
 
-    parser.add_argument("--list-models", action="store_true", help="List available LLMs for use with --model, based on the available LLM providers")
+    parser.add_argument(
+        "--list-models",
+        action="store_true",
+        help="List available LLMs for use with --model, based on the available LLM providers",
+    )
 
     parser.add_argument(
         "--set",
@@ -54,17 +58,22 @@ def parse_arguments():
     return parser.parse_args()
 
 
+def print_models(config):
+    print("Available models:")
+    print()
+    print("\n".join(["- " + key for key in sorted(config.providers)]))
+    print()
+    print("Use --model to specify the default model.")
+
+
 async def main():
     args = parse_arguments()
     config = load_config()
 
     if args.list_models:
-        print("Available models:")
-        print()
-        print("\n".join(["- " + key for key in config.providers]))
-        print()
-        print("Use --model to specify")
+        print_models(config)
         return
+
     config.parameters = dict(args.variables or {})
     for file_path in args.INPUT_FILES:
         if os.path.isfile(file_path):
diff --git a/python/src/providers/openai.py b/python/src/providers/openai.py
index aabfdff..5957c1e 100644
--- a/python/src/providers/openai.py
+++ b/python/src/providers/openai.py
@@ -14,7 +14,7 @@ def __init__(self, api_key: str = None, models=None, *args, **kwargs):
         openai.api_key = api_key or os.getenv("OPENAI_API_KEY")
         models = models or [
             model.id for model in openai.models.list().data
-            if "gpt" in model.id
+            if "gpt" in model.id or "o1" in model.id
         ]
         for model_name in models:
             self.add(