fix(hot-reloader): disable zlib compression with falsey value

- set `zlib.output_compression` to 0 instead of Off at runtime
- document the HotReloader fix

Signed-off-by: memleakd <121398829+memleakd@users.noreply.github.com>

Author: memleakd

system/HotReloader/HotReloader.php

@@ -24,7 +24,8 @@ public function run(): void
             session_write_close();
         }
 
-        ini_set('zlib.output_compression', 'Off');
+        // Use "0" because ini_get() returns "Off" as a truthy string at runtime.
+        ini_set('zlib.output_compression', '0');
 
         header('Cache-Control: no-store');
         header('Content-Type: text/event-stream');

user_guide_src/source/changelogs/v4.7.3.rst

@@ -45,6 +45,7 @@ Bugs Fixed
 - **Database:** Fixed a bug where ``BaseConnection::listTables()`` could return a sparse array when using cached table names after a table was dropped.
 - **Database:** Fixed a bug where the PostgreSQL driver's ``increment()`` and ``decrement()`` methods were not working for numeric columns.
 - **Database:** Fixed a bug where the SQLSRV driver's decrement method was adding instead of subtracting the decrement value when ``$castTextToInt`` was false.
+- **HotReloader:** Fixed a bug where disabling ``zlib.output_compression`` could leave a truthy ``Off`` runtime value that caused later requests in long-running workers to fail the output-buffer guard.
 - **Kint:** Fixed a bug where stale Content Security Policy nonces were reused in worker mode, causing browser CSP violations for Debug Toolbar assets.
 - **Language:** Fixed a bug where ``Language::getLine()`` returned the literal dot-notation key instead of the nested array value when the requested key resolved to an intermediate array three or more levels deep.
 - **Toolbar:** Fixed a bug where the Logs collector raised an undefined property error when using a third-party PSR-3 logger.