docs: add Spring Break 2x usage promo note + ICM evaluation

- Guide: documented Anthropic March 13-27 2026 promotion (2x limits outside 5-11am PT / all weekends), with CET timezone conversion for European users - Resource evaluation: ICM Infinite Context Memory MCP server (score 3/5) - CHANGELOG: both entries under [Unreleased] Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
2026-03-15 18:34:55 +01:00 · 2026-03-15 18:34:55 +01:00 · d9cff74d71
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--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@ -8,6 +8,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).

 ### Added

+- **Spring Break promotion note** (guide line ~2395): Documented Anthropic's March 13-27, 2026 promotion — 2x usage limits outside 5-11am PT (peak hours) and all weekends, bonus usage doesn't count against weekly limits, applies to Free/Pro/Max/Team. Includes CET timezone conversion for European users (2x from midnight-13h and 19h-24h France time). Source: Anthropic support article.
 - **ICM (Infinite Context Memory)**: New MCP memory server section after Kairn (~line 11365) — Rust single binary, zero deps, Homebrew install, dual architecture (episodic decay Memories + permanent knowledge graph Memoirs), 9 typed relation types, auto-extraction 3 layers, 14 editor clients. Score 3/5 — recommended as Rust-native alternative when Python dependency management is a friction point. Includes explicit license callout (Source-Available, free ≤20 people) and vendor-reported benchmark flags.
 - **Comparison matrix update**: Added ICM column to MCP memory stack matrix (Runtime + License rows added for all tools)

--- a/docs/resource-evaluations/icm-infinite-context-memory.md
+++ b/docs/resource-evaluations/icm-infinite-context-memory.md
@ -0,0 +1,113 @@
+# Resource Evaluation: ICM (Infinite Context Memory)
+
+**Date**: 2026-03-14
+**URL**: https://github.com/rtk-ai/icm
+**Type**: GitHub repository / MCP server
+**Score**: 3/5 — Integrated
+**Decision**: Added as section after Kairn in `guide/ultimate-guide.md` (~line 11365)
+
+---
+
+## Summary
+
+ICM is a persistent memory MCP server from the rtk-ai team (same authors as RTK/Rust Token Killer). It provides a dual memory architecture: "Memories" (episodic, configurable decay) and "Memoirs" (permanent knowledge graph with 9 typed relation types). Distributed as a single Rust binary with zero external dependencies, installable via Homebrew.
+
+### Key Points
+
+- Single Rust binary, SQLite, zero deps — Homebrew install
+- Dual architecture: episodic decay + permanent knowledge graph in one tool
+- Hybrid search: BM25 30% + vector similarity 70%
+- Auto-deduplication (>85% similarity blocked)
+- Auto-extraction: pattern hooks, pre-compaction, session-start
+- Supports 14 editors/clients (Claude Code, Cursor, VS Code, Windsurf, Zed, Amp, Cline, etc.)
+- 52 stars, 55 commits as of March 2026
+- License: Source-Available (free for individuals and teams ≤20; enterprise license required above)
+
+---
+
+## Scoring
+
+| Criterion | Score |
+|-----------|-------|
+| Relevance to Claude Code users | 4/5 |
+| Differentiation from existing content | 3/5 |
+| Maturity / adoption signal | 2/5 |
+| License openness | 2/5 |
+| **Overall** | **3/5** |
+
+---
+
+## Comparison vs Existing Guide Content
+
+| Feature | doobidoo | Kairn | ICM |
+|---------|----------|-------|-----|
+| Language | Python | Python | Rust (single binary) |
+| Install | pip | pip | Homebrew |
+| Episodic decay | No | Yes (biological) | Yes (configurable) |
+| Permanent knowledge graph | No | Yes | Yes (Memoirs) |
+| Auto-extraction | No | No | Yes |
+| License | MIT | MIT | Source-Available |
+
+Main differentiator: zero-dependency Rust binary lowers install friction for users who struggle with Python environments. Conceptual overlap with Kairn (knowledge graph + decay) is real but the runtime difference is meaningful.
+
+---
+
+## Benchmarks
+
+All benchmarks below are **vendor-reported by rtk-ai** — not independently verified.
+
+**Storage performance (1000 ops, 384d embeddings)**:
+- Store (no embeddings): 34.2 µs/op
+- Store (with embeddings): 51.6 µs/op
+- FTS5 full-text search: 46.6 µs/op
+- Vector search (KNN): 590.0 µs/op
+- Hybrid search: 951.1 µs/op
+
+**Agent efficiency (Haiku model, multi-session)**:
+- Session 2: 29% fewer turns, 32% less input context, 17% cost reduction
+- Session 3: 40% fewer turns, 44% less context, 22% cost reduction
+
+**Knowledge retention (10 questions)**:
+- Without ICM: 5%
+- With ICM: 68%
+
+Note: The knowledge retention benchmark uses a sample of 10 questions on Haiku — too narrow for generalization.
+
+---
+
+## Fact-Check
+
+| Claim | Status | Source |
+|-------|--------|--------|
+| Storage: 34.2 µs/op | ✅ | README benchmarks section |
+| Hybrid search: ~951 µs/op | ✅ | README benchmarks section |
+| 29-40% turn reduction | ✅ present / ⚠️ vendor-reported | README — rtk-ai self-evaluation |
+| 68% vs 5% knowledge retention | ✅ present / ⚠️ vendor-reported, n=10 | README |
+| Source-Available license, free ≤20 | ✅ | LICENSE file |
+| 9 Memoir relation types | ✅ | README full list |
+| 14 supported clients | ✅ | `icm init` documentation |
+| 52 stars | ✅ | GitHub as of 2026-03-14 |
+
+No hallucinations detected. All figures present in the source README.
+
+---
+
+## License Note
+
+Source-Available license. Free for individuals and teams of up to 20 people. **Enterprise license required for organizations above 20 people.** Contact: license@rtk.ai
+
+This was flagged in the guide entry with an explicit callout. Teams should verify their org size before deploying.
+
+---
+
+## Integration Location
+
+- New section: `guide/ultimate-guide.md` after Kairn (~line 11365), before "MCP Memory Stack: Complementarity Patterns"
+- Comparison matrix updated: ICM column added with Runtime and License rows
+
+## Upgrade Trigger
+
+Revisit for 4/5 if:
+- Benchmarks independently verified by community
+- Adoption exceeds 500+ stars with sustained commit activity
+- License changes to MIT/Apache
--- a/guide/ultimate-guide.md
+++ b/guide/ultimate-guide.md
@ -2394,6 +2394,10 @@ Monthly cost estimate: $50-$200 for 5-10 developers

 > **Note**: Anthropic's plans evolve frequently. Always verify current pricing and limits at [claude.com/pricing](https://claude.com/pricing).

+> **Spring Break Promotion (March 13-27, 2026)**: Anthropic is running a 2-week promotion with **2x usage limits outside peak hours**. Peak hours are 5-11am PT (8am-2pm ET). All other hours — including evenings, nights, early mornings — get doubled usage. Weekends are fully 2x all day. Bonus usage does **not** count against your weekly plan limits. Applies to Free, Pro, Max, and Team plans (Enterprise excluded). Source: [Anthropic support article](https://support.claude.com/en/articles/14063676-claude-march-2026-usage-promotion).
+>
+> **For European users**: 5-11am PT = 13h-19h CET (France). So 2x applies from midnight to 1pm and from 7pm to midnight, plus all weekends.
+
 **How Subscription Limits Work**

 Unlike API usage (pay-per-token), subscriptions use a hybrid model that's deliberately opaque:
@ -11363,6 +11367,88 @@ git clone https://github.com/kairn-ai/kairn && cd kairn && pip install -e .

 > **Source**: [kairn-ai/kairn GitHub](https://github.com/kairn-ai/kairn) (MIT, Python 100%)

+### ICM: Dual Memory Architecture (Rust Binary, Zero Dependencies)
+
+> **⚠️ Status: Under Testing** — Evaluated March 2026. Source-Available license (free for individuals and teams ≤20). From the rtk-ai team (same authors as RTK). Benchmarks below are vendor-reported and unverified independently. Feedback welcome!
+
+**Purpose**: Persistent memory for AI agents combining episodic decay (Memories) and permanent knowledge graph (Memoirs) in a single zero-dependency Rust binary.
+
+**When ICM makes sense over Kairn/doobidoo**:
+- Python dependency management is a friction point (CI environments, sandboxed machines)
+- You want Homebrew install with no Python env setup
+- You need both decay-based episodic memory and a permanent knowledge graph in one tool
+- You use multiple editors (14 clients supported: Claude Code, Cursor, VS Code, Windsurf, Zed, Amp, Cline, Roo Code, OpenAI Codex CLI, and more)
+
+**Key differentiators vs Kairn/doobidoo**:
+- **Single Rust binary**: no Python, no pip, no virtual env — `brew install icm` and done
+- **Dual architecture in one tool**: Memories (decay, episodic) + Memoirs (permanent, typed graph) — Kairn covers the graph layer, doobidoo the semantic layer, ICM covers both
+- **Auto-extraction**: three-layer automatic capture (pattern hooks, pre-compaction, session-start) without explicit `store_memory` calls
+- **Auto-deduplication**: blocks entries with >85% similarity to existing content
+
+| Feature | doobidoo | Kairn | ICM |
+|---------|----------|-------|-----|
+| Language | Python | Python | Rust (single binary) |
+| Install | pip | pip | Homebrew / curl |
+| Episodic decay | No | Yes (biological) | Yes (configurable rates) |
+| Permanent knowledge graph | No | Yes | Yes (Memoirs) |
+| Auto-extraction | No | No | Yes (3 layers) |
+| Hybrid search | Semantic | Full-text + semantic | BM25 30% + vector 70% |
+| License | MIT | MIT | Source-Available |
+
+**Memoir relation types** (9): `part_of`, `depends_on`, `related_to`, `contradicts`, `refines`, `alternative_to`, `caused_by`, `instance_of`, `superseded_by`
+
+**Installation**:
+
+```bash
+# Homebrew (recommended)
+brew tap rtk-ai/tap && brew install icm
+
+# Quick install
+curl -fsSL https://raw.githubusercontent.com/rtk-ai/icm/main/install.sh | sh
+
+# From source
+cargo install --path crates/icm-cli
+```
+
+**MCP Config** (auto-configured via `icm init`):
+
+```bash
+icm init   # interactive setup — detects and configures your editor
+```
+
+**Usage**:
+
+```bash
+# Store episodic memory (auto-decay)
+icm store -t "my-project" -c "Use PostgreSQL for main DB" -i high
+
+# Recall with hybrid search
+icm recall "database choice" --topic "my-project"
+
+# Build permanent knowledge graph
+icm memoir create -n "system-architecture"
+icm memoir add-concept -m "system-architecture" -n "auth-service"
+icm memoir link -m "system-architecture" --from "api-gateway" --to "auth-service" -r depends-on
+```
+
+**Performance** (1000 ops, 384d embeddings — vendor-reported):
+
+| Operation | Latency |
+|-----------|---------|
+| Store (no embeddings) | 34.2 µs/op |
+| Store (with embeddings) | 51.6 µs/op |
+| FTS5 full-text search | 46.6 µs/op |
+| Vector search (KNN) | 590.0 µs/op |
+| Hybrid search | 951.1 µs/op |
+
+**Agent efficiency claims** (vendor-reported, Haiku model, unverified independently):
+- Session 2: 29% fewer turns, 17% cost reduction
+- Session 3: 40% fewer turns, 22% cost reduction
+
+> ⚠️ **License note**: Free for individuals and teams of up to 20 people. Enterprise license required above that threshold. Verify your organization's size before deploying. Contact: license@rtk.ai
+
+> **Source**: [rtk-ai/icm GitHub](https://github.com/rtk-ai/icm) (52 stars, Source-Available)
+
 ### MCP Memory Stack: Complementarity Patterns

 > **⚠️ Experimental** - These patterns combine multiple MCP servers. Test in your workflow before relying on them.
@ -11389,15 +11475,18 @@ git clone https://github.com/kairn-ai/kairn && cd kairn && pip install -e .

 **Comparison Matrix**:

-| Capability | Serena | grepai | doobidoo | Kairn |
-|------------|--------|--------|----------|-------|
-| Cross-session memory | Key-value | No | Semantic | Knowledge graph |
-| Cross-IDE memory | No | No | Yes | Yes |
-| Cross-device sync | No | No | Yes (Cloudflare) | No |
-| Knowledge Graph | No | Call graph | Decision graph | Typed relationships |
-| Fuzzy search | No | Code | Memory | Full-text + semantic |
-| Tags/categories | No | No | Yes | Yes |
-| Memory decay / auto-expiry | No | No | No | Yes (biological) |
+| Capability | Serena | grepai | doobidoo | Kairn | ICM |
+|------------|--------|--------|----------|-------|-----|
+| Cross-session memory | Key-value | No | Semantic | Knowledge graph | Episodic + graph |
+| Cross-IDE memory | No | No | Yes | Yes | Yes (14 clients) |
+| Cross-device sync | No | No | Yes (Cloudflare) | No | No |
+| Knowledge Graph | No | Call graph | Decision graph | Typed relationships | Typed relationships |
+| Fuzzy search | No | Code | Memory | Full-text + semantic | BM25 + vector hybrid |
+| Tags/categories | No | No | Yes | Yes | Yes (topics) |
+| Memory decay / auto-expiry | No | No | No | Yes (biological) | Yes (configurable) |
+| Auto-extraction | No | No | No | No | Yes (3 layers) |
+| Runtime | — | — | Python | Python | Rust (single binary) |
+| License | MIT | MIT | MIT | MIT | Source-Available (≤20 free) |

 **Usage Patterns**: