Add channel-memory SQLite adapter example

examples/channel-memory/.claw-describe.json

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+{
+  "version": 2,
+  "description": "Channel-memory adapter for source-backed Discord channel awareness digests",
+  "endpoints": [
+    {
+      "method": "POST",
+      "path": "/ingest",
+      "description": "Retain one source channel message with stable message identity and content hash"
+    },
+    {
+      "method": "POST",
+      "path": "/source-messages",
+      "description": "Fetch exact retained source messages by channel and message id"
+    },
+    {
+      "method": "POST",
+      "path": "/digest",
+      "description": "Return deterministic digest blocks over retained source messages"
+    },
+    {
+      "method": "POST",
+      "path": "/coverage-gaps",
+      "description": "Record an explicit source coverage gap for a channel and time range"
+    },
+    {
+      "method": "POST",
+      "path": "/forget",
+      "description": "Suppress retained source messages and mark derived blocks dirty"
+    },
+    {
+      "method": "GET",
+      "path": "/health",
+      "description": "Health check"
+    }
+  ]
+}

examples/channel-memory/Dockerfile

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+FROM golang:1.23-alpine AS builder
+WORKDIR /src
+COPY go.mod go.sum ./
+RUN go mod download
+COPY examples/channel-memory ./examples/channel-memory
+RUN CGO_ENABLED=0 go build -o /channel-memory ./examples/channel-memory
+
+FROM alpine:3.20
+RUN apk add --no-cache wget
+COPY --from=builder /channel-memory /channel-memory
+COPY examples/channel-memory/.claw-describe.json /.claw-describe.json
+EXPOSE 8080
+HEALTHCHECK --interval=5s --timeout=3s --retries=6 \
+    CMD wget -qO- http://localhost:8080/health > /dev/null || exit 1
+CMD ["/channel-memory"]

examples/channel-memory/README.md

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+# Channel Memory Adapter
+
+This is the first executable slice of the digest-backed channel-awareness design.
+It is a standalone HTTP service; `claw-wall` does not call it yet.
+
+The adapter stores Discord-style channel messages in SQLite and keeps exact
+source provenance for later digest-backed `channel-awareness` work.
+
+## Endpoints
+
+- `POST /ingest` stores one source message. Idempotency is keyed by
+  `(source_kind, channel_id, message_id, content_hash)`.
+- `POST /source-messages` fetches exact retained source messages by channel and
+  message id. By default it returns the current non-deleted version; set
+  `include_history: true` to inspect older content-hash versions.
+- `POST /digest` returns deterministic digest blocks over already-retained
+  messages. It does not call an LLM.
+- `POST /coverage-gaps` records an explicit missing source range.
+- `POST /forget` suppresses source messages and marks derived blocks dirty.
+- `GET /health` reports process liveness.
+
+## Deterministic Processor
+
+The deterministic path is intentionally conservative:
+
+- preserves obvious hard events as faithful `hard_event` blocks
+- keeps ordinary retained content as `raw_excerpt` blocks
+- collapses runtime/status noise into sparse `telemetry_count` blocks
+- emits coverage-gap metadata from stored gap records
+- creates tombstone blocks for deleted messages without carrying deleted content
+
+Higher-quality `topic_rollup` and `sequence_rollup` blocks belong to the async
+LLM worker tracked separately.
+
+## Storage
+
+State is stored under `CHANNEL_MEMORY_DIR` and defaults to
+`/data/channel-memory`. Set `CHANNEL_MEMORY_DB` to choose an exact SQLite file.
+
+The schema includes:
+
+- `source_messages`
+- `derived_blocks`
+- `derived_block_sources`
+- `coverage_gaps`
+- `processing_queue`
+
+`source_messages` uses explicit `observed_seq`, `observed_at`, and `is_current`
+fields so edited messages create new rows while exact retrieval can still select
+the current version deterministically.
+
+## Build
+
+This Dockerfile expects the repository root as build context because the service
+uses the repository Go module:
+
+```sh
+docker build -f examples/channel-memory/Dockerfile -t channel-memory:latest .
+```