Add prompt templating system with mustache

- Add promptsDir to Paths.hs for $AVA_DATA_ROOT/prompts/
- Create Omni.Agent.Prompts module with:
  - Mustache template loading and rendering
  - Automatic partial resolution via automaticCompile
  - Frontmatter/metadata parsing for list command
- Create omni-agent-prompt CLI for previewing prompts:
  - list: show all available prompts
  - render: render prompt with --var and --json context
- Prompts use .mustache extension for automaticCompile compatibility
- Partials referenced with full extension: {{> shared/memory.mustache}}

1 files changed, 110 insertions, 0 deletions

diff --git a/Omni/Agent/Prompts/Cli.hs b/Omni/Agent/Prompts/Cli.hs
new file mode 100644
index 0000000..c0a792f
--- /dev/null
+++ b/Omni/Agent/Prompts/Cli.hs
@@ -0,0 +1,110 @@
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE NoImplicitPrelude #-}
+
+-- | CLI tool for previewing and debugging prompt templates.
+--
+-- Usage:
+--   omni-agent-prompt list
+--   omni-agent-prompt agents/telegram/system
+--   omni-agent-prompt subagents/coder/system --var namespace=Omni/Jr --var task="Add feature"
+--   omni-agent-prompt subagents/generic/system --json '{"task":"Research X","role_description":"research"}'
+--
+-- : out omni-agent-prompt
+-- : dep aeson
+-- : dep bytestring
+-- : dep text
+-- : dep mustache
+-- : dep unordered-containers
+module Omni.Agent.Prompts.Cli (main) where
+
+import Alpha
+import qualified Data.Aeson as Aeson
+import qualified Data.Aeson.Key as Key
+import qualified Data.Aeson.KeyMap as KeyMap
+import qualified Data.ByteString.Lazy as BL
+import qualified Data.Text as Text
+import qualified Data.Text.Encoding as TE
+import qualified Data.Text.IO as TextIO
+import qualified Omni.Agent.Prompts as Prompts
+import qualified System.Environment as Env
+import qualified System.Exit as Exit
+
+main :: IO ()
+main = do
+  args <- Env.getArgs
+  case args of
+    [] -> usage
+    ["--help"] -> usage
+    ["-h"] -> usage
+    ["list"] -> listPrompts
+    (pid : rest) -> renderPromptCmd (Text.pack pid) rest
+
+usage :: IO ()
+usage = do
+  putText "omni-agent-prompt - Preview and debug prompt templates"
+  putText ""
+  putText "Usage:"
+  putText "  omni-agent-prompt list"
+  putText "  omni-agent-prompt <prompt-id> [--var key=value]... [--json '{...}']"
+  putText ""
+  putText "Examples:"
+  putText "  omni-agent-prompt agents/telegram/system"
+  putText "  omni-agent-prompt subagents/coder/system --var namespace=Omni/Jr --var task='Add feature'"
+  putText "  omni-agent-prompt subagents/generic/system --json '{\"task\":\"Research X\"}'"
+  putText ""
+  putText <| "Prompts directory: " <> Text.pack Prompts.promptsDir
+
+listPrompts :: IO ()
+listPrompts = do
+  prompts <- Prompts.listPrompts
+  if null prompts
+    then do
+      putText "No prompts found."
+      putText <| "Prompts directory: " <> Text.pack Prompts.promptsDir
+    else do
+      putText "Available prompts:"
+      putText ""
+      forM_ prompts <| \(pid, meta) -> do
+        let desc = fromMaybe "" (Prompts.pmDescription meta)
+        if Text.null desc
+          then putText <| "  " <> pid
+          else putText <| "  " <> pid <> " - " <> desc
+
+renderPromptCmd :: Text -> [String] -> IO ()
+renderPromptCmd pid args = do
+  let (jsonCtx, kvPairs) = parseArgs args
+  ctx <- case jsonCtx of
+    Nothing -> pure <| buildContext kvPairs
+    Just jsonStr -> case Aeson.decode (BL.fromStrict (TE.encodeUtf8 jsonStr)) of
+      Nothing -> do
+        putText <| "Error: Invalid JSON: " <> jsonStr
+        Exit.exitFailure
+      Just obj -> pure <| mergeContext obj kvPairs
+
+  result <- Prompts.renderPrompt pid ctx
+  case result of
+    Left err -> do
+      putText <| "Error: " <> err
+      Exit.exitFailure
+    Right rendered -> TextIO.putStrLn rendered
+
+parseArgs :: [String] -> (Maybe Text, [(Text, Text)])
+parseArgs = go Nothing []
+  where
+    go json kvs [] = (json, reverse kvs)
+    go _json kvs ("--json" : val : rest) = go (Just (Text.pack val)) kvs rest
+    go json kvs ("--var" : kv : rest) =
+      case Text.breakOn "=" (Text.pack kv) of
+        (k, v)
+          | not (Text.null v) -> go json ((k, Text.drop 1 v) : kvs) rest
+          | otherwise -> go json kvs rest
+    go json kvs (_ : rest) = go json kvs rest
+
+buildContext :: [(Text, Text)] -> Aeson.Value
+buildContext kvs =
+  Aeson.Object <| KeyMap.fromList [(Key.fromText k, Aeson.String v) | (k, v) <- kvs]
+
+mergeContext :: Aeson.Value -> [(Text, Text)] -> Aeson.Value
+mergeContext (Aeson.Object obj) kvs =
+  Aeson.Object <| foldr (\(k, v) m -> KeyMap.insert (Key.fromText k) (Aeson.String v) m) obj kvs
+mergeContext _ kvs = buildContext kvs