refactor: replace 3-Sets diagnostic with focused attention filters and memory

The 3-Sets framework doesn't transfer well to agents — all three
dimensions are fully visible and controllable config, not hidden
human psychology. Removed the branding, kept the practical bits:

- attention-filters: what context each archetype receives (token savings)
- memory: persistent learnings across orchestrations (project knowledge)

skills/attention-filters/SKILL.md

@@ -0,0 +1,39 @@
+---
+name: attention-filters
+description: Use when spawning archetype agents to decide what context each agent receives. Reduces token waste and sharpens focus by passing only relevant artifacts.
+---
+
+# Attention Filters
+
+Each archetype needs different context. Pass only what's relevant — not everything.
+
+| Archetype | Receives | Does NOT Receive |
+|-----------|----------|-----------------|
+| Explorer | Task description, codebase access | Prior proposals or reviews |
+| Creator | Explorer's research + task description | Implementation details |
+| Maker | Creator's proposal | Explorer's research, reviews |
+| Guardian | Maker's git diff + proposal risk section | Explorer's research |
+| Skeptic | Creator's proposal (focus: assumptions) | Git diff details |
+| Trickster | Maker's git diff only | Everything else |
+| Sage | Proposal + implementation + diff | Explorer's raw research |
+
+## Why This Matters
+
+- **Token cost:** A Guardian reading the Explorer's 2000-word research wastes ~2600 tokens on irrelevant context
+- **Focus:** An agent with too much context drifts from its archetype's concern
+- **Shadow prevention:** Over-loading context encourages rabbit-holing (Explorer) and scope creep (Maker)
+
+## In Practice
+
+When spawning a Check-phase agent, include only the filtered context in the prompt:
+
+```
+# Guardian receives:
+"Review these changes: <git diff output>
+The proposal identified these risks: <risks section only>
+Verdict: APPROVED or REJECTED with findings."
+
+# NOT:
+"Here is the full research, the full proposal, the full implementation,
+the full git log, and everything else we have..."
+```