Provision on first prompt — mid-session installs never fired SessionStart

.claude-plugin/plugin.json

@@ -13,7 +13,11 @@
         "git+https://github.com/nickroci/ultan@main",
         "ultan",
         "mcp"
-      ]
+      ],
+      "env": {
+        "CLAUDE_PLUGIN_ROOT": "${CLAUDE_PLUGIN_ROOT}",
+        "CLAUDE_PLUGIN_DATA": "${CLAUDE_PLUGIN_DATA}"
+      }
     }
   }
 }

README.md

@@ -47,18 +47,23 @@ 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.
+The plugin provisions that retrieval stack into its private storage **in the
+background**, triggered by whichever happens first: the plugin's MCP server starting
+(right after install/reload — the spec has no install-time script, so this is the
+earliest the plugin gets to run), a fresh session's `SessionStart`, or your next
+prompt. All three funnel into one lock-guarded installer, so they never race. 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
           }
         ]

tests/test_mcp_provision.py

@@ -0,0 +1,62 @@
+"""The MCP server start is the plugin's earliest code execution after
+/plugin install — _kick_provisioner must fire the background installer
+exactly when the runtime is missing, and never otherwise."""
+
+from pathlib import Path
+
+import pytest
+
+from ultan import _mcp
+
+
+@pytest.fixture()
+def spawn_spy(monkeypatch: pytest.MonkeyPatch) -> list[list[str]]:
+    calls: list[list[str]] = []
+
+    class _FakeProc:
+        pass
+
+    def _fake_popen(cmd: list[str], **kwargs: object) -> _FakeProc:
+        calls.append(cmd)
+        return _FakeProc()
+
+    monkeypatch.setattr(_mcp.subprocess, "Popen", _fake_popen)
+    return calls
+
+
+def _plugin_dirs(tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> tuple[Path, Path]:
+    root = tmp_path / "plugin-root"
+    (root / "scripts").mkdir(parents=True)
+    (root / "scripts" / "ensure-ultan.sh").write_text("#!/bin/bash\n", encoding="utf-8")
+    data = tmp_path / "plugin-data"
+    data.mkdir()
+    monkeypatch.setenv("CLAUDE_PLUGIN_ROOT", str(root))
+    monkeypatch.setenv("CLAUDE_PLUGIN_DATA", str(data))
+    return root, data
+
+
+def test_kick_fires_installer_when_unprovisioned(
+    tmp_path: Path, monkeypatch: pytest.MonkeyPatch, spawn_spy: list[list[str]]
+) -> None:
+    root, _data = _plugin_dirs(tmp_path, monkeypatch)
+    _mcp._kick_provisioner()
+    assert spawn_spy == [["bash", str(root / "scripts" / "ensure-ultan.sh")]]
+
+
+def test_kick_noop_when_already_provisioned(
+    tmp_path: Path, monkeypatch: pytest.MonkeyPatch, spawn_spy: list[list[str]]
+) -> None:
+    _root, data = _plugin_dirs(tmp_path, monkeypatch)
+    (data / "bin").mkdir()
+    (data / "bin" / "ultan").write_text("#!/bin/bash\n", encoding="utf-8")
+    _mcp._kick_provisioner()
+    assert spawn_spy == []
+
+
+def test_kick_noop_without_plugin_root(
+    tmp_path: Path, monkeypatch: pytest.MonkeyPatch, spawn_spy: list[list[str]]
+) -> None:
+    monkeypatch.delenv("CLAUDE_PLUGIN_ROOT", raising=False)
+    monkeypatch.setenv("CLAUDE_PLUGIN_DATA", str(tmp_path / "nope"))
+    _mcp._kick_provisioner()
+    assert spawn_spy == []

ultan/_mcp.py

@@ -14,12 +14,51 @@
 
 from __future__ import annotations
 
+import os
+import subprocess
+from pathlib import Path
 from typing import TYPE_CHECKING
 
 if TYPE_CHECKING:
     from mcp.server.fastmcp import FastMCP
 
 
+def _kick_provisioner() -> None:
+    """Fire the plugin's background installer if the runtime isn't provisioned.
+
+    The plugin spec has no install-time script, but Claude Code starts this
+    MCP server right after `/plugin install` + `/reload-plugins` — the
+    earliest code the plugin gets to run — so kicking here makes provisioning
+    start at install time in practice. Idempotent and cheap: ensure-ultan.sh
+    returns immediately and holds an atomic install lock, so overlapping
+    kicks from the MCP server, SessionStart, and the first-prompt fallback
+    all collapse into one install. plugin.json passes CLAUDE_PLUGIN_ROOT /
+    CLAUDE_PLUGIN_DATA into our env; missing vars degrade to a no-op (the
+    other triggers still cover provisioning)."""
+    data = os.environ.get("CLAUDE_PLUGIN_DATA") or str(
+        Path.home() / ".claude" / "plugins" / "data" / "ultan-ultan"
+    )
+    if (Path(data) / "bin" / "ultan").exists():
+        return  # already provisioned
+    root = os.environ.get("CLAUDE_PLUGIN_ROOT")
+    if not root:
+        return
+    script = Path(root) / "scripts" / "ensure-ultan.sh"
+    if not script.exists():
+        return
+    try:
+        subprocess.Popen(
+            ["bash", str(script)],
+            env={**os.environ, "CLAUDE_PLUGIN_DATA": data},
+            stdout=subprocess.DEVNULL,  # the installer logs to install.log itself
+            stderr=subprocess.DEVNULL,
+            stdin=subprocess.DEVNULL,
+            start_new_session=True,
+        )
+    except OSError:
+        pass
+
+
 def build_server() -> "FastMCP":
     """Construct the FastMCP server and register tools. Pure construction — no
     daemon spawn, no I/O — so it's unit-testable."""
@@ -48,11 +87,13 @@ def ultan_recall(query: str) -> str:  # pyright: ignore[reportUnusedFunction]  #
 
 
 def serve() -> int:
-    """Run the MCP server over stdio (what Claude Code launches). Async-spawns
-    the daemon first so memory comes up in the background without blocking the
-    MCP handshake or hitting Claude Code's server-startup timeout."""
+    """Run the MCP server over stdio (what Claude Code launches). Kicks the
+    plugin provisioner if the runtime is missing (closest thing to an
+    install-time hook — see _kick_provisioner), then async-spawns the daemon;
+    neither blocks the MCP handshake or Claude Code's server-startup timeout."""
     from . import _daemon
 
+    _kick_provisioner()
     _daemon.ensure_running()
     build_server().run()
     return 0