docs: Update CLAUDE.md with memory leak investigation session

- Documented v0.4.1 through v0.4.9 fix attempts
- Listed all protection mechanisms in place
- Recorded key learnings about WordPress hooks and recursion
- Status: unresolved, documented as known incompatibility

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
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2026-02-02 20:10:09 +01:00
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@@ -552,3 +552,58 @@ wp-fedistream/
- Uses Gitea API directly for release creation (not GitHub Actions) - Uses Gitea API directly for release creation (not GitHub Actions)
- Submodule uses relative URL for CI compatibility - Submodule uses relative URL for CI compatibility
- Composer symlinks from `lib/wc-licensed-product-client` to vendor - Composer symlinks from `lib/wc-licensed-product-client` to vendor
### 2026-02-02 - Memory Leak Investigation v0.4.1 through v0.4.9
**Summary:** Investigated memory exhaustion issue when WP FediStream is used with WP Prometheus plugin. Multiple fix attempts were made but the root cause remains unresolved.
**Problem:**
- PHP Fatal error: Allowed memory size exhausted (1GB)
- Error locations varied: Twig StagingExtension.php, Environment.php, ExtensionSet.php, WordPress class-wp-hook.php
- Only occurs when WP Prometheus plugin is also active
- Suspected infinite recursion through WordPress hook system
**Fix Attempts (v0.4.1 - v0.4.8):**
1. **v0.4.1** - Added recursion depth tracking in `get_post_data()`, skip `the_content` filter at depth > 1
2. **v0.4.2** - Added `$in_shortcode_context` flag, all shortcode render methods enter context before data loading
3. **v0.4.3** - Changed boolean to counter (`$shortcode_context_depth`), added context to `template-wrapper.php`
4. **v0.4.4** - Fixed `get_the_excerpt()` which internally triggers `the_content` filter
5. **v0.4.5** - Added render depth tracking in `Plugin::render()`, strip shortcodes from content
6. **v0.4.6** - Added `$loading_page_template` flag to block shortcode rendering during page template loading
7. **v0.4.7** - Added `$rendering_main_template` hard lock in `Plugin::render()`, reduced MAX_RENDER_DEPTH to 2
8. **v0.4.8** - Nuclear option: ALWAYS skip `the_content` filter (didn't work, reverted)
**v0.4.9 - Current State:**
- Reverted nuclear option
- Kept all other protections in place
- Issue documented in README.md as known incompatibility
**Files Modified:**
- `includes/Frontend/TemplateLoader.php` - Multiple recursion protection mechanisms
- `includes/Frontend/Shortcodes.php` - Shortcode context entry, page template loading check
- `includes/Frontend/template-wrapper.php` - Page template loading flag, main template render flag
- `includes/Plugin.php` - Render depth tracking, main template rendering lock
- `README.md` - Added Known Issues section
**Protection Mechanisms in Place:**
1. `$recursion_depth` counter in `get_post_data()` (max 3)
2. `$shortcode_context_depth` counter for nested shortcodes
3. `$loading_page_template` flag blocks shortcode rendering during page load
4. `$rendering_main_template` flag in `Plugin::render()` blocks parallel renders
5. `MAX_RENDER_DEPTH = 2` in `Plugin::render()`
6. Skip `the_content` and `get_the_excerpt()` when in protected context
7. Strip shortcodes from content when skipping content filter
**Key Learnings:**
- `get_the_excerpt()` internally calls `apply_filters('the_content', ...)` when generating auto-excerpts
- `the_content` filter triggers `do_shortcode()` which can cause recursive shortcode processing
- WordPress hook system (class-wp-hook.php) can itself be the recursion point
- The interaction between FediStream and WP Prometheus appears to be at a fundamental WordPress level
**Status:** UNRESOLVED - Documented as known incompatibility, investigation to continue later