Add v1.4–v1.7 milestones to ROADMAP

ROADMAP.md

@@ -4,6 +4,48 @@ This document tracks the planned evolution of SafeMemoize through v1.0.0 and bey
 
 ---
 
+## v1.4.0 — Developer Experience
+
+*Goal: reduce boilerplate for classes with many memoized methods and add a safety rail for shared mutable cached values.*
+
+| Feature | Description | Status |
+|---|---|---|
+| Per-class default options | `safe_memoize_options ttl: 60, max_size: 100` class-level macro that sets option defaults shared by every `memoize` call on the class; per-call options still override | Planned |
+| Copy-on-read | `memoize :config, copy_on_read: true` — returns a `dup` (or `deep_dup` when available) of the cached value on every read, preventing callers from mutating shared cached state | Planned |
+
+---
+
+## v1.5.0 — Cache Invalidation
+
+*Goal: group-level cache invalidation so related methods can be busted in one operation.*
+
+| Feature | Description | Status |
+|---|---|---|
+| Memoization groups | `memoize :find, group: :database` then `reset_memo_group(:database)` to invalidate all methods tagged with the same group at once; groups can span multiple methods on the same class | Planned |
+
+---
+
+## v1.6.0 — Resilience
+
+*Goal: make external-store memoization resilient to infrastructure failures.*
+
+| Feature | Description | Status |
+|---|---|---|
+| Circuit breaker for external stores | When a `store:` adapter raises on `read` or `write`, automatically fall back to the per-instance in-process hash rather than propagating the exception; configurable error threshold and recovery probe interval | Planned |
+
+---
+
+## v1.7.0 — Advanced Store Features
+
+*Goal: multi-process performance patterns for high-traffic deployments.*
+
+| Feature | Description | Status |
+|---|---|---|
+| Multi-level (L1/L2) caching | `store: [memory_store, redis_store]` — check in-process first, fall back to the remote store on miss, and promote to L1 on read; each level can have independent TTL and eviction settings | Planned |
+| Stampede protection | Probabilistic early expiry (XFetch algorithm) for external stores; recomputes slightly before a TTL expires to prevent multiple processes hitting a cold miss simultaneously | Planned |
+
+---
+
 ## v2.0.0 — Next Generation (Long Horizon)
 
 *Goal: incorporate real-world usage feedback, clean up accumulated API surface, and open a path for advanced extension.*