feat: automatic per-turn recall (UserPromptSubmit) for Claude Code

CHANGELOG.md

@@ -5,6 +5,13 @@ Format: [Keep a Changelog](https://keepachangelog.com/en/1.1.0/); versioning: [S
 
 ## [Unreleased]
 
+### Added
+- **Automatic per-turn recall on Claude Code.** A `UserPromptSubmit` hook runs a
+  hybrid recall against each substantive prompt and injects the hits as context,
+  closing the gap where the `recall` tool was almost never invoked. New
+  `cairn recall-hook` command; configurable via `auto_recall` / `auto_recall_k` /
+  `auto_recall_scope` (default on). Plugin `0.4.0`.
+
 ### Fixed
 - **Claude Code plugin (0.3.1): fresh install no longer fails on first run.** The
   SessionStart/SessionEnd/PreCompact hooks passed `${user_config.vault_path}` as a command

README.md

@@ -42,6 +42,21 @@ codex plugin add agentcairn@agentcairn
 
 On install you pick a vault path (default `~/agentcairn`); it's **auto-created** on the first session — no Obsidian setup required. From then on agentcairn surfaces relevant memory at the start of each session, distills each session into your vault, and gives you `/agentcairn:recall`, `/remember`, `/memory`, `/savings`, and `/ingest`. Nothing to pip-install — the plugin runs the published package via `uvx`.
 
+**Automatic recall (Claude Code).** On every substantive prompt, the plugin runs
+a hybrid recall against what you just asked and injects the most relevant
+memories as context for that turn — not just the recency digest shown at session
+start. Trivially-short prompts (e.g. "yes", "go") are skipped. It is fail-open:
+if anything goes wrong it injects nothing and never blocks your prompt.
+
+Configure it in `~/.agentcairn/config.toml` (flat top-level keys; env vars
+`CAIRN_AUTO_RECALL`, `CAIRN_AUTO_RECALL_K`, `CAIRN_AUTO_RECALL_SCOPE` override the file):
+
+```toml
+auto_recall       = true    # master on/off (default: true)
+auto_recall_k     = 3       # memories injected per prompt
+auto_recall_scope = "all"   # "all" (boost, non-lossy) or "project" (hard filter)
+```
+
 > Not on Claude Code or Codex? agentcairn is also a standalone MCP server + CLI for any host — see [Using it directly](#using-it-directly).
 
 ## How it works