Initial Arka plugin registry: Official plugins mirror + Arka-signed index

11 plugins from github.com/librefang/librefang-registry plugins/.
index.json / index.json.sig are signed with Arka's Ed25519 key
(not upstream stats.librefang.ai). Private key is not in this repo.

plugins/context-decay/README.md

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+# context-decay
+
+Time-based memory decay with relevance scoring. Memories lose confidence over time (5% per day) and are only recalled when they pass both a decay threshold and a relevance check against the current message. Implements "use it or lose it" -- recalled memories get their access timestamps refreshed.
+
+## How it works
+
+**After each turn**, the plugin extracts memorable statements from the conversation:
+
+- User preferences ("I prefer...", "I use...")
+- Decisions ("let's use...", "we decided...")
+- Important facts (names, versions, URLs)
+- Corrections ("no, actually...", "that's wrong...")
+
+Similar memories are reinforced (confidence +0.1, cap 1.0). All memories receive a decay pass, and those below 0.1 confidence are pruned.
+
+**On ingest**, each memory's confidence is decayed based on time elapsed, then scored for relevance to the current message via keyword overlap. The composite score `decayed_confidence * (0.5 + 0.5 * relevance)` must exceed 0.3 to be recalled. Recalled memories get their `last_accessed` timestamp updated.
+
+## Hooks
+
+| Hook | Script | Description |
+|------|--------|-------------|
+| ingest | `hooks/ingest.py` | Applies decay, scores relevance, returns top 5 memories above threshold |
+| after_turn | `hooks/after_turn.py` | Extracts new memories, reinforces similar ones, prunes decayed entries |
+
+## Storage
+
+Memories are stored at `~/.librefang/plugins/context-decay/{agent_id}.json`. Max 100 memories per agent. Decay formula: `confidence * 0.95^(hours / 24)`.
+
+## Usage
+
+Installed automatically when enabled in agent configuration.