docs: document ~/.claude/CLAUDE.md compatibility behavior (anomalyco#8268)

Author: zeke

packages/web/src/content/docs/rules.mdx

@@ -3,7 +3,7 @@ title: Rules
 description: Set custom instructions for opencode.
 ---
 
-You can provide custom instructions to opencode by creating an `AGENTS.md` file. This is similar to `CLAUDE.md` or Cursor's rules. It contains instructions that will be included in the LLM's context to customize its behavior for your specific project.
+You can provide custom instructions to opencode by creating an `AGENTS.md` file. This is similar to Cursor's rules. It contains instructions that will be included in the LLM's context to customize its behavior for your specific project.
 
 ---
 
@@ -58,24 +58,41 @@ opencode also supports reading the `AGENTS.md` file from multiple locations. And
 
 ### Project
 
-The ones we have seen above, where the `AGENTS.md` is placed in the project root, are project-specific rules. These only apply when you are working in this directory or its sub-directories.
+Place an `AGENTS.md` in your project root for project-specific rules. These only apply when you are working in this directory or its sub-directories.
 
 ### Global
 
 You can also have global rules in a `~/.config/opencode/AGENTS.md` file. This gets applied across all opencode sessions.
 
 Since this isn't committed to Git or shared with your team, we recommend using this to specify any personal rules that the LLM should follow.
 
+### Claude Code Compatibility
+
+For users migrating from Claude Code, OpenCode supports Claude Code's file conventions as fallbacks:
+
+- **Project rules**: `CLAUDE.md` in your project directory (used if no `AGENTS.md` exists)
+- **Global rules**: `~/.claude/CLAUDE.md` (used if no `~/.config/opencode/AGENTS.md` exists)
+- **Skills**: `~/.claude/skills/` — see [Agent Skills](/docs/skills/) for details
+
+To disable Claude Code compatibility, set one of these environment variables:
+
+```bash
+export OPENCODE_DISABLE_CLAUDE_CODE=1        # Disable all .claude support
+export OPENCODE_DISABLE_CLAUDE_CODE_PROMPT=1 # Disable only ~/.claude/CLAUDE.md
+export OPENCODE_DISABLE_CLAUDE_CODE_SKILLS=1 # Disable only .claude/skills
+```
+
 ---
 
 ## Precedence
 
-So when opencode starts, it looks for:
+When opencode starts, it looks for rule files in this order:
 
-1. **Local files** by traversing up from the current directory
-2. **Global file** by checking `~/.config/opencode/AGENTS.md`
+1. **Local files** by traversing up from the current directory (`AGENTS.md`, `CLAUDE.md`, or `CONTEXT.md`)
+2. **Global file** at `~/.config/opencode/AGENTS.md`
+3. **Claude Code file** at `~/.claude/CLAUDE.md` (unless disabled)
 
-If you have both global and project-specific rules, opencode will combine them together.
+The first matching file wins in each category. For example, if you have both `AGENTS.md` and `CLAUDE.md`, only `AGENTS.md` is used. Similarly, `~/.config/opencode/AGENTS.md` takes precedence over `~/.claude/CLAUDE.md`.
 
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