make LLM support optional

 * LLM support can be installed with new extras "llm" or "all"
 * conditionally import "llm" and "llm.cli"
 * show alternative message when user attempts to use \llm without
   dependencies available.  Unlike ssh extras, there is no need to exit
   on failure.
 * cache the list of possible CLI commands for performance, avoiding a
   regression
 * provide environment variable to turn off LLM support even in the
   presence of the llm dependency
 * update quickstart to recommend installing with the "all" extra
 * update changelog
 * update doc/llm.md

Author: rolandwalker

README.md

@@ -20,7 +20,7 @@ If you already know how to install Python packages, then you can install it via
 You might need sudo on Linux.
 
 ```bash
-pip install -U mycli
+pip install -U 'mycli[all]'
 ```
 
 or

changelog.md

@@ -1,6 +1,11 @@
 Upcoming (TBD)
 ==============
 
+Features
+--------
+* Make LLM dependencies an optional extra.
+
+
 Internal
 --------
 * Add mypy to Pull Request template.

doc/llm.md

@@ -8,13 +8,22 @@ Alias: `\ai` works the same as `\llm`.
 
 ## Quick Start
 
-1) Configure your API key (only needed for remote providers like OpenAI):
+1) Make sure mycli is installed with the `[llm]` extras, like
+```bash
+pip install 'mycli[llm]'
+```
+or that the `llm` dependency is installed separately:
+```bash
+pip install llm
+```
+
+2) From the mycli prompt, configure your API key (only needed for remote providers like OpenAI):
 
 ```text
 \llm keys set openai
 ```
 
-2) Ask a question. The response’s SQL (inside a ```sql fenced block) is extracted and pre-filled at the prompt:
+3) Ask a question. The response’s SQL (inside a ```sql fenced block) is extracted and pre-filled at the prompt:
 
 ```text
 World> \llm "Capital of India?"
@@ -165,6 +174,16 @@ World> \llm templates show mycli-llm-template
 - Data sent: Contextual questions send schema (table/column names and types) and a single sample row per table. Review your data sensitivity policies before using remote models; prefer local models (such as ollama) if needed.
 - Help: Running `\llm` with no arguments shows a short usage message.
 
+## Turning Off LLM Support
+
+To turn off LLM support even when the `llm` dependency is installed, set the `MYCLI_LLM_OFF` environment variable:
+```bash
+export MYCLI_LLM_OFF=1
+```
+
+This may be desirable for faster startup times.
+
+
 ---
 
 ## Learn More

mycli/packages/special/llm.py

@@ -1,4 +1,5 @@
 import contextlib
+import functools
 import io
 import logging
 import os
@@ -10,15 +11,30 @@
 from typing import Optional, Tuple
 
 import click
-import llm
-from llm.cli import cli
+
+try:
+    if not os.environ.get('MYCLI_LLM_OFF'):
+        import llm
+
+        LLM_IMPORTED = True
+    else:
+        LLM_IMPORTED = False
+except ImportError:
+    LLM_IMPORTED = False
+try:
+    if not os.environ.get('MYCLI_LLM_OFF'):
+        from llm.cli import cli
+
+        LLM_CLI_IMPORTED = True
+    else:
+        LLM_CLI_IMPORTED = False
+except ImportError:
+    LLM_CLI_IMPORTED = False
 
 from mycli.packages.special.main import Verbosity, parse_special_command
 
 log = logging.getLogger(__name__)
 
-LLM_CLI_COMMANDS = list(cli.commands.keys())
-MODELS = {x.model_id: None for x in llm.get_models()}
 LLM_TEMPLATE_NAME = "mycli-llm-template"
 
 
@@ -67,7 +83,7 @@ def build_command_tree(cmd):
     if isinstance(cmd, click.Group):
         for name, subcmd in cmd.commands.items():
             if cmd.name == "models" and name == "default":
-                tree[name] = MODELS
+                tree[name] = {x.model_id: None for x in llm.get_models()}
             else:
                 tree[name] = build_command_tree(subcmd)
     else:
@@ -76,7 +92,7 @@ def build_command_tree(cmd):
 
 
 # Generate the command tree for autocompletion
-COMMAND_TREE = build_command_tree(cli) if cli else {}
+COMMAND_TREE = build_command_tree(cli) if LLM_CLI_IMPORTED is True else {}
 
 
 def get_completions(tokens, tree=COMMAND_TREE):
@@ -120,7 +136,25 @@ def __init__(self, results=None):
 # Plugins directory
 # https://llm.datasette.io/en/stable/plugins/directory.html
 """
+
+NEED_DEPENDENCIES = """
+To enable LLM features you need to install mycli with LLM support:
+
+    pip install 'mycli[llm]'
+
+or
+
+    pip install 'mycli[all]'
+
+or install LLM libraries separately
+
+   pip install llm
+
+This is required to use the \\llm command.
+"""
+
 _SQL_CODE_FENCE = r"```sql\n(.*?)\n```"
+
 PROMPT = """
 You are a helpful assistant who is a MySQL expert. You are embedded in a mysql
 cli tool called mycli.
@@ -159,8 +193,16 @@ def ensure_mycli_template(replace=False):
     return
 
 
+@functools.cache
+def cli_commands() -> list[str]:
+    return list(cli.commands.keys())
+
+
 def handle_llm(text, cur) -> Tuple[str, Optional[str], float]:
     _, verbosity, arg = parse_special_command(text)
+    if not LLM_IMPORTED:
+        output = [(None, None, None, NEED_DEPENDENCIES)]
+        raise FinishIteration(output)
     if not arg.strip():
         output = [(None, None, None, USAGE)]
         raise FinishIteration(output)
@@ -176,7 +218,7 @@ def handle_llm(text, cur) -> Tuple[str, Optional[str], float]:
         capture_output = False
         use_context = False
         restart = True
-    elif parts and parts[0] in LLM_CLI_COMMANDS:
+    elif parts and parts[0] in cli_commands():
         capture_output = False
         use_context = False
     elif parts and parts[0] == "--help":

pyproject.toml

@@ -21,9 +21,6 @@ dependencies = [
     "pyperclip >= 1.8.1",
     "pycryptodomex",
     "pyfzf >= 0.3.1",
-    "llm>=0.19.0",
-    "setuptools",                   # Required by llm commands to install models
-    "pip",
 ]
 
 [build-system]
@@ -35,6 +32,15 @@ build-backend = "setuptools.build_meta"
 
 [project.optional-dependencies]
 ssh = ["paramiko", "sshtunnel"]
+llm = [
+    "llm>=0.19.0",
+    "setuptools",                   # Required by llm commands to install models
+    "pip",
+]
+all = [
+  "mycli[ssh]",
+  "mycli[llm]",
+]
 dev = [
     "behave>=1.2.6",
     "coverage>=7.2.7",
@@ -46,6 +52,9 @@ dev = [
     "pdbpp>=0.10.3",
     "paramiko",
     "sshtunnel",
+    "llm>=0.19.0",
+    "setuptools",                   # Required by llm commands to install models
+    "pip",
 ]
 
 [project.scripts]