docs: add MEMORY.md with lessons learned from 4X4.md

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: noelsaw1

MEMORY.md

@@ -0,0 +1,35 @@
+## Lessons Learned (from 4X4.md, 2026-04-05)
+
+### No [Unreleased] section in CHANGELOG
+**Type:** feedback
+
+Use versioned blocks on commit instead of batching changes in an [Unreleased] bucket. At solo/small-team velocity, every commit gets a version block immediately, so the unreleased bucket just accumulated stale entries nobody reviewed.
+
+**How to apply:** Always create a new `## [X.Y.Z] - YYYY-MM-DD` block. Never add `[Unreleased]`. The CHANGELOG maintainer rules in the file header enforce this.
+
+---
+
+### Promote experimental scripts after 4+ hardening commits
+**Type:** feedback
+
+Scripts with 4+ consecutive hardening releases should move out of `experimental/` to reduce confusion about maturity. Leaving hardened scripts in `experimental/` signals instability that no longer exists.
+
+**How to apply:** When a script in `experimental/` accumulates 4+ commits focused on fixes, edge cases, or robustness, recommend promotion to `tools/` or the appropriate mainline directory.
+
+---
+
+### VS Code extension value is zero-config MCP onboarding
+**Type:** project
+
+The extension's real value is zero-config workspace onboarding (MCP server auto-discovery), not wrapping terminal commands with UI chrome. Users already have CLI and MCP tools — the extension eliminates the manual wiring step.
+
+**How to apply:** Prioritize features that reduce setup friction (file watchers, config merging, provider auto-registration). Avoid duplicating functionality already available via MCP tools or CLI.
+
+---
+
+### Wire placeholder features immediately
+**Type:** feedback
+
+Don't create a file and leave it disconnected. `.wpcignore` existed as a placeholder but was never wired into WPCC, leaving repo-wide scans broken by false positives. Placeholder files create a false sense of completeness.
+
+**How to apply:** Wire config files, templates, or feature stubs into the consuming code in the same PR. If the integration isn't ready, document the gap in a TODO or issue instead of creating a disconnected file.