docs(features): full Phase 1 + 2 + 3 + 3.5 inventory in FEATURES.md

[AVADSA25]

Summary

Per user request + external review (Copilot): every feature shipped since the v2.2 baseline must be enumerated in FEATURES.md as the single source of truth.

This PR adds 122 new features across 4 new sections (10-13), bringing the total from 245 → 367.

Header changes

Field	Before	After
Engine version	v2.1	v2.3
Features	245	367
Skills	60	74
Tests	378	1023
Lines of code	34K+	53K+

What's added

Modified existing sections

• Section 2 — CODEC Chat (24 → 30 features): added 4-mode composer (Chat / Think / Agents / Project), Project mode dispatch, auto project folder, inline plan review buttons, agent status pills, auto-escalation gate, per-conversation silence
• Section 6 — CODEC Skills (60 → 78 features): refreshed to 74 skills + 4 infrastructure entries. Added: file_write, web_fetch, ask_user, stuck, self_improve, shift_report, clipboard_url_fetch, audit_report, backup_status, health_check, notification_reader, imessage_send, tts_say, auto_memorize, fact_extract, memory_save, plus the SKILL_OBSERVATION_TRIGGER declarative-trigger infrastructure entry

NEW sections

Section 10 — Phase 1 Agent Substrate (18 features) (v2.3)
Unified audit envelope, paired correlation_id contract, 5 plugin lifecycle hooks, AskUserQuestion + §1.7 strict-consent gate, stuck-detection ring buffer, step budget per turn, self_improve as plugin, 3 kill switches.

Section 11 — Phase 2 Continuous Observation + Automation (24 features) (v2.3)
codec-observer PM2 daemon, 10-min RAM RingBuffer, observation-injection contract, OCR-with-retry, image redaction, slow-poll degraded mode, SKILL_OBSERVATION_TRIGGER declarative triggers (5 matcher types), persistent kill state with sha8 keys, end-of-day shift_report skill, 3 trigger paths (time/idle/manual), per-day dedup.

Section 12 — Phase 3 Drop-a-Project Autonomous Agents (32 features) (v2.3)
Step 8 Plan + Permission Contract (10 features) — Plan/Checkpoint/PermissionManifest dataclasses, Qwen-3.6 plan drafter, vague-description clarifying loop, plan-hash tamper detection, global allowlist tier, 9 PWA endpoints. Step 9 Background Execution + Permission Gate (12 features) — codec-agent-runner daemon, Action dataclass, permission_gate matrix, strict-consent universal floor, resume after PM2 restart, 3-concurrent cap, extend_budget endpoint, 4 PWA endpoints, 8 audit events. Step 10 Proactive Messaging + Auto-Escalation (10 features) — AgentMessage, post_message with 60s batching, user reply pickup, silence kill-switch, 5 lifecycle emit sites, classifier with 2-signal gate + Q11 session silence, 3 PWA endpoints.

Section 13 — Phase 3.5 UX Polish + Proactive Overlay (24 features) (v2.3)
Project mode UI in codec_chat.html (5 features: Project chip, instructions panel, sendMessage Project branch, viewAgentPlan, status pills). Project folder Claude Code-style (5 features: auto-creation, slugify, collision disambiguation, manifest.project_dir, plan-drafter prompt extension). Proactive intelligence overlay (4 features: codec_proactive.py opt-in, long_form_dwell v1 pattern, 3-gate kill model, rate limits). Step 9 review polish (5 features: blocked_on_qwen + auto-resume, reads_path field + symmetric expansion, recovery_cid threading). Multi-channel notifications (3 features: macOS / iMessage / Telegram). Phase 3 fast-follow (2 features: extend_budget endpoint + 3 new audit events).

Summary table

| Product / Phase | Features |
|---|:-:|
| 1. CODEC Core | 26 |
| 2. CODEC Chat | 30 |
| 3. CODEC Dashboard | 32 |
| 4. CODEC Vibe | 20 |
| 5. CODEC Agents | 20 |
| 6. CODEC Skills | 78 |
| 7. CODEC Infrastructure | 36 |
| 8. CODEC Dictate | 15 |
| 9. CODEC Instant | 12 |
| 10. Phase 1 — Agent Substrate (v2.3) | 18 |
| 11. Phase 2 — Continuous Observation + Automation (v2.3) | 24 |
| 12. Phase 3 — Drop-a-Project Autonomous Agents (v2.3) | 32 |
| 13. Phase 3.5 — UX Polish + Proactive Overlay (v2.3) | 24 |
| TOTAL | 367 |

Test plan

• No code changes — pure docs PR
• All Sections 1-9 preserved (only count adjustments where new features fit existing product lines)
• All 4 new sections (10-13) cite their corresponding docs/PHASE*-*.md design docs
• Post-merge: README's badge counts match (already updated to match in PR fix(tests + readme): audit-log test pollution + Phase 3 README refresh #26)

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