fix(plugin): provision on first prompt — /reload-plugins never fires SessionStart

Installing mid-session left the plugin looking alive (skills/commands/MCP
hot-load) while silently capturing nothing: provisioning was wired only to
SessionStart, which /reload-plugins does not fire, so ensure-ultan.sh never
ran and every per-turn hook no-op'd on the missing binary — until the next
fresh session.

The UserPromptSubmit hook now falls back to the provisioner when the binary
is absent: first prompt after a mid-session install kicks off the background
install (instant return, atomic-lock idempotent — repeat prompts exit on the
lock). SessionStart wiring is unchanged for the fresh-session path.

README quick-start now tells the truth about /reload-plugins, and the
bin/ultan wrapper's not-provisioned message says "send any message" instead
of "start a new session".

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: nickroci

README.md

@@ -47,18 +47,21 @@ Inside Claude Code:
 > hundred MB) in the background, and you can keep working while it finishes.
 
 That's it. Skills and slash commands hot-load the instant you install; `/reload-plugins`
-pulls in the hooks and the MCP server. **A full Claude Code restart is not required** — a
-fresh session also works, but you don't need one.
+pulls in the hooks and the MCP server. **A full Claude Code restart is not required** —
+your next prompt kicks off provisioning automatically (a fresh session works too; you
+don't need one).
 
 > 🩺 **Wondering what it's doing? Ask Claude to run `ultan doctor`.** It reports
 > whether the background install is still running, the daemon's state (warming /
 > healthy / idle), priming latency, and capture freshness — at any stage, even
 > mid-install.
 
-On first use a `SessionStart` hook provisions that retrieval stack into the plugin's
-private storage **in the background**. Until it finishes, priming falls back to a fast
-lexical scan; after that the daemon **lazy-starts on demand**. Models download anonymously
-from HuggingFace — see *First-start expectations* below.
+On first use the plugin provisions that retrieval stack into its private storage
+**in the background** — triggered by `SessionStart` in a fresh session, or by your
+first prompt when you installed mid-session (`/reload-plugins` alone doesn't fire
+`SessionStart`, so the prompt hook covers that path). Until it finishes, priming
+falls back to a fast lexical scan; after that the daemon **lazy-starts on demand**.
+Models download anonymously from HuggingFace — see *First-start expectations* below.
 
 You now have:
 

bin/ultan

@@ -37,7 +37,7 @@ if [ -f "$LOG" ]; then
   echo "ultan: a new Claude Code session retries automatically." >&2
   exit 1
 fi
-echo "ultan: not provisioned yet — the plugin installs Ultan in the background at" >&2
-echo "ultan: session start (progress lands in $DATA/install.log)." >&2
-echo "ultan: if this is a fresh install, start a new session or wait a minute." >&2
+echo "ultan: not provisioned yet — the plugin installs Ultan in the background," >&2
+echo "ultan: triggered by session start OR your next prompt (progress lands in" >&2
+echo "ultan: $DATA/install.log). Send any message and try again in a minute." >&2
 exit 1

hooks/hooks.json

@@ -21,7 +21,7 @@
         "hooks": [
           {
             "type": "command",
-            "command": "[ -x \"${CLAUDE_PLUGIN_DATA}/bin/ultan\" ] && \"${CLAUDE_PLUGIN_DATA}/bin/ultan\" hook user-prompt-submit || true",
+            "command": "if [ -x \"${CLAUDE_PLUGIN_DATA}/bin/ultan\" ]; then \"${CLAUDE_PLUGIN_DATA}/bin/ultan\" hook user-prompt-submit; else \"${CLAUDE_PLUGIN_ROOT}/scripts/ensure-ultan.sh\"; fi || true",
             "timeout": 5
           }
         ]