The Partial Reading Problem

You notice that Claude follows your first five CLAUDE.md rules perfectly but ignores the last three. Or Claude follows all rules at the start of a session but drifts away from them after extended conversation. This is not random – it has specific, diagnosable causes.

Cause 1: File Length Exceeding 200 Lines

The most common cause. When CLAUDE.md exceeds the recommended 200-line maximum, rules near the bottom receive less attention. Claude’s instruction adherence is strongest for rules near the top of the context and weakens as the context grows.

Diagnostic:

# Check your file length
wc -l CLAUDE.md

# Identify which rules are being ignored — they are probably near the bottom
tail -50 CLAUDE.md

Fix: Restructure so your most critical rules appear in the first 50 lines:

# Lines 1-50: Critical rules (architecture, security, error handling)
# Lines 51-100: Important rules (naming, testing)
# Lines 101-150: Nice-to-have rules (style preferences)

Better yet, split into .claude/rules/ files with path patterns so each file stays short and loads conditionally.

Cause 2: Compaction Dropped Nested Files

Claude Code’s auto-compaction summarizes long conversations to stay within context limits. During compaction:

• Project-root CLAUDE.md: Survives. Re-read from disk after compaction.
• Nested CLAUDE.md (subdirectories): NOT re-injected automatically. Reloads when Claude next reads a file in that subdirectory.
• Conversation-only instructions: Lost permanently.

Diagnostic:

If rules worked at the start of a session but stopped after extended conversation, compaction likely dropped them.

# Run /memory after a long session
# Check if nested CLAUDE.md files are still listed
# If they disappeared, compaction dropped them

Fix: Move critical instructions to the project-root CLAUDE.md. This file always survives compaction because Claude re-reads it from disk:

# ./CLAUDE.md (project root — survives compaction)
## Critical Rules
- All database access through repositories
- Error handling uses Result types
- No default exports

# Import less critical rules that can reload on demand
@src/api/CLAUDE.md

Cause 3: Contradicting Instructions

When two rules contradict each other, Claude follows one and ignores the other. This looks like partial reading, but it is actually a conflict:

# Rule in CLAUDE.md line 15:
- Return errors as exceptions using throw

# Rule in CLAUDE.md line 85:
- Return errors as Result<T, AppError>

# Claude follows one, ignores the other — appears as partial reading

Diagnostic:

Search for topics mentioned multiple times:

grep -n "error\|throw\|exception\|Result" CLAUDE.md

Fix: Remove the contradicting rule. Each topic should appear exactly once.

Cause 4: Rules Too Vague to Verify

Claude follows specific rules and skips vague ones:

# These get followed (specific):
- Function names start with a verb: get, set, create, delete
- Maximum function body: 40 lines
- No any type — use unknown

# These get skipped (vague):
- Write clean code
- Follow best practices
- Keep things organized

Diagnostic: Read each ignored rule and ask: “Can Claude check this with a yes/no test?” If not, the rule is too vague.

Fix: Rewrite vague rules as concrete, verifiable statements.

Cause 5: Path-Specific Rules Not Matching

If you use .claude/rules/ with path patterns, rules only load when Claude reads files matching the glob. If Claude does not read any matching files during a session, the rules never load:

# .claude/rules/api-design.md
---
paths:
  - "src/routes/**/*.ts"
---
# These rules only load when Claude reads files in src/routes/

Diagnostic: Run /memory to see which rules files are currently loaded. Ask Claude to read a file matching the glob, then run /memory again to see if the rules file appears.

Fix: Rules that must always be active should NOT have path patterns. Remove the paths frontmatter or move the rules to the root CLAUDE.md.

Diagnostic Summary

For splitting long CLAUDE.md files, see the length optimization guide. For diagnosing conflict-specific issues, see the conflicting instructions fix guide. For the complete CLAUDE.md loading specification, see the CLAUDE.md complete guide.