docs: update Claude Code releases to v2.1.49

- Updated latest tracked version: v2.1.47 → v2.1.49
- v2.1.49 highlights: --worktree/-w flag + subagent isolation:worktree,
  background:true for agents, ConfigChange hook event, simple mode file edit
- Updated CHANGELOG [Unreleased] with CC release tracking entry

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

CHANGELOG.md

@@ -6,6 +6,14 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 ## [Unreleased]
 
+### Documentation
+
+- **Claude Code Releases**: Updated tracking to v2.1.49
+  - `--worktree` / `-w` CLI flag + subagent `isolation: "worktree"` for isolated git worktrees
+  - `background: true` in agent definitions to always run as background task
+  - `ConfigChange` hook event for enterprise security auditing
+  - Simple mode now includes file edit tool; Sonnet 4.6 now has 1M context on Max plan
+
 ### Added
 
 - **Talk Preparation Pipeline** — 6-stage skill pipeline: raw material → conference talk → Kimi slides

guide/claude-code-releases.md

@@ -10,13 +10,13 @@ tags: [reference, release]
 > **Full details**: [github.com/anthropics/claude-code/CHANGELOG.md](https://github.com/anthropics/claude-code/blob/main/CHANGELOG.md)
 > **Machine-readable**: [claude-code-releases.yaml](../machine-readable/claude-code-releases.yaml)
 
-**Latest**: v2.1.47 | **Updated**: 2026-02-19
+**Latest**: v2.1.49 | **Updated**: 2026-02-20
 
 ---
 
 ## Quick Jump
 
-- [2.1.x Series (January-February 2026)](#21x-series-january-february-2026) — Fast mode Opus 4.6, PDF pages support, /debug command, Task management, claude.ai MCP connectors
+- [2.1.x Series (January-February 2026)](#21x-series-january-february-2026) — Worktree isolation, background agents, ConfigChange hook, Fast mode Opus 4.6, claude.ai MCP connectors
 - [2.0.x Series (Nov 2025 - Jan 2026)](#20x-series-november-2025---january-2026) — Opus 4.5, Claude in Chrome, Background agents
 - [Breaking Changes Summary](#breaking-changes-summary)
 - [Milestone Features](#milestone-features)
@@ -25,6 +25,34 @@ tags: [reference, release]
 
 ## 2.1.x Series (January-February 2026)
 
+### v2.1.49 (2026-02-20)
+
+- **New**: `--worktree` / `-w` CLI flag to start Claude in an isolated git worktree
+- **New**: Subagents support `isolation: "worktree"` for working in a temporary git worktree
+- **New**: `background: true` field in agent definitions to always run as a background task
+- **New**: `ConfigChange` hook event — fires when configuration files change during a session (enterprise security auditing + blocking)
+- **New**: Plugins can ship `settings.json` for default configuration
+- **New**: `--from-pr` flag to resume sessions linked to a specific GitHub PR (+ sessions auto-linked when created via `gh pr create`)
+- **New**: `PreToolUse` hooks can return `additionalContext` to the model
+- **New**: `plansDirectory` setting to customize where plan files are stored
+- **New**: `auto:N` syntax for configuring MCP tool search auto-enable threshold
+- **New**: `Setup` hook event triggered via `--init`, `--init-only`, or `--maintenance` CLI flags
+- **Changed**: Sonnet 4.5 1M context removed from Max plan — Sonnet 4.6 now has 1M context (switch in `/model`)
+- **Changed**: Simple mode now includes file edit tool (not just Bash)
+- **Fixed**: File-not-found errors now suggest corrected paths when model drops repo folder
+- **Fixed**: Ctrl+C and ESC silently ignored when background agents running + main thread idle (double-press within 3s now kills all agents)
+- **Fixed**: Plugin `enable`/`disable` auto-detects correct scope (no longer defaults to user scope)
+- **Fixed**: Context window blocking limit calculated too aggressively (~65% instead of ~98%)
+- **Fixed**: Memory issues causing crashes with parallel subagents
+- **Fixed**: Memory leak in long sessions where stream resources not cleaned up
+- **Fixed**: `@` symbol incorrectly triggering file autocomplete in bash mode
+- **Fixed**: Background agent results returning raw transcript data instead of final answer
+- **Fixed**: Slash command autocomplete selecting wrong command (e.g. `/context` vs `/compact`)
+- **Improved**: `@` mention file suggestion speed (~3× faster in git repos)
+- **Improved**: MCP connection: `list_changed` notification support for dynamic tool updates without reconnection
+- **Improved**: Skills invoke progress display; skill suggestions prioritize recently/frequently used
+- **Improved**: Incremental output for async agents; token count includes background agent tokens
+
 ### v2.1.47 (2026-02-19)
 
 - **Improved**: VS Code plan preview auto-updates as Claude iterates; commenting enabled only when plan is ready for review; preview stays open when rejected for revision

machine-readable/claude-code-releases.yaml

@@ -3,8 +3,8 @@
 # Purpose: Track Claude Code product releases for documentation sync
 # Maintained: Manual updates when new releases are announced
 
-latest: "2.1.47"
-updated: "2026-02-19"
+latest: "2.1.49"
+updated: "2026-02-20"
 
 # ════════════════════════════════════════════════════════════════
 # RELEASES (newest first, condensed highlights only)
@@ -15,6 +15,15 @@ releases:
   # 2.1.x Series (January-February 2026)
   # ─────────────────────────────────────────────────────────────
 
+  - version: "2.1.49"
+    date: "2026-02-20"
+    highlights:
+      - "⭐ `--worktree` / `-w` flag to start Claude in isolated git worktree; subagents support `isolation: 'worktree'`"
+      - "Agent definitions support `background: true` to always run as background task"
+      - "`ConfigChange` hook event for enterprise security auditing (fires when config files change during session)"
+      - "Simple mode now includes file edit tool; many bug fixes for background agents, permissions, sessions"
+    breaking: []
+
   - version: "2.1.47"
     date: "2026-02-19"
     highlights: