feedback: not-relevant/not-useful commands, edge strength adjustment

Add adjust_edge_strength() to Store — modifies strength on all edges
between two nodes, clamped to [0.05, 0.95].

New commands:
- `not-relevant KEY` — weakens ALL edges to the node by 0.01
  (bad routing: search found the wrong thing)
- `not-useful KEY` — weakens node weight, not edges
  (bad content: search found the right thing but it's not good)

Enhanced `used KEY` — now also strengthens all edges to the node by
0.01, in addition to the existing node weight boost.

Three-tier design: agents adjust by 0.00001 (automatic), conscious
commands adjust by 0.01 (deliberate), manual override sets directly.
All clamped, never hitting 0 or 1.

Design spec: .claude/analysis/2026-03-14-link-strength-feedback.md

Co-Authored-By: Kent Overstreet <kent.overstreet@linux.dev>

poc-memory/.claude/analysis/2026-03-14-link-strength-feedback.md

@@ -0,0 +1,98 @@
+# Link Strength Feedback Design
+_2026-03-14, designed with Kent_
+
+## The two signals
+
+### "Not relevant" → weaken the EDGE
+The routing failed. Search followed a link and arrived at a node that
+doesn't relate to what I was looking for. The edge carried activation
+where it shouldn't have.
+
+- Trace back through memory-search's recorded activation path
+- Identify which edge(s) carried activation to the bad result
+- Weaken those edges by a conscious-scale delta (0.01)
+
+### "Not useful" → weaken the NODE
+The routing was correct but the content is bad. The node itself isn't
+valuable — stale, wrong, poorly written, duplicate.
+
+- Downweight the node (existing `poc-memory wrong` behavior)
+- Don't touch the edges — the path was correct, the destination was bad
+
+## Three tiers of adjustment
+
+### Tier 1: Agent automatic (0.00001 per event)
+- Agent follows edge A→B during a run
+- If the run produces output that gets `used` → strengthen A→B
+- If the run produces nothing useful → weaken A→B
+- The agent doesn't know this is happening — daemon tracks it
+- Clamped to [0.05, 0.95] — edges can never hit 0 or 1
+- Logged: every adjustment recorded with (agent, edge, delta, timestamp)
+
+### Tier 2: Conscious feedback (0.01 per event)
+- `poc-memory not-relevant KEY` → trace activation path, weaken edges
+- `poc-memory not-useful KEY` → downweight node
+- `poc-memory used KEY` → strengthen edges in the path that got here
+- 100x stronger than agent signal — deliberate judgment
+- Still clamped, still logged
+
+### Tier 3: Manual override (direct set)
+- `poc-memory graph link-strength SRC DST VALUE` → set directly
+- For when we know exactly what a strength should be
+- Rare, but needed for bootstrapping / correction
+
+## Implementation: recording the path
+
+memory-search already computes the spread activation trace. Need to:
+1. Record the activation path for each result (which edges carried how
+   much activation to arrive at this node)
+2. Persist this per-session so `not-relevant` can look it up
+3. The `record-hits` RPC already sends keys to the daemon — extend
+   to include (key, activation_path) pairs
+
+## Implementation: agent tracking
+
+In the daemon's job functions:
+1. Before LLM call: record which nodes and edges the agent received
+2. After LLM call: parse output for LINK/WRITE_NODE actions
+3. If actions are created and later get `used` → the input edges were useful
+4. If no actions or actions never used → the input edges weren't useful
+5. This is a delayed signal — requires tracking across time
+
+Simpler first pass: just track co-occurrence. If two nodes appear
+together in a successful agent run, strengthen the edge between them.
+No need to track which specific edge was "followed."
+
+## Clamping
+
+```rust
+fn adjust_strength(current: f32, delta: f32) -> f32 {
+    (current + delta).clamp(0.05, 0.95)
+}
+```
+
+Edges can asymptotically approach 0 or 1 but never reach them.
+This prevents dead edges (can always be revived by strong signal)
+and prevents edges from becoming unweakenable.
+
+## Logging
+
+Every adjustment logged as JSON event:
+```json
+{"ts": "...", "event": "strength_adjust", "source": "agent|conscious|manual",
+ "edge": ["nodeA", "nodeB"], "old": 0.45, "new": 0.4501, "delta": 0.0001,
+ "reason": "co-retrieval in linker run c-linker-42"}
+```
+
+This lets us:
+- Watch the distribution shift over time
+- Identify edges that are oscillating (being pulled both ways)
+- Tune the delta values based on observed behavior
+- Roll back if something goes wrong
+
+## Migration from current commands
+
+- `poc-memory wrong KEY [CTX]` → splits into `not-relevant` and `not-useful`
+- `poc-memory used KEY` → additionally strengthens edges in activation path
+- Both old commands continue to work for backward compat, mapped to the
+  most likely intent (wrong → not-useful, used → strengthen path)