diff --git a/packages/coding-agent/CHANGELOG.md b/packages/coding-agent/CHANGELOG.md
index 2f7b500ff..1d9949caf 100644
--- a/packages/coding-agent/CHANGELOG.md
+++ b/packages/coding-agent/CHANGELOG.md
@@ -7,6 +7,13 @@
 ### Changed
 
 - Send the `omp/<version>` User-Agent on xAI chat (`xai` and `xai-oauth`) unless the request already set its own ([#8840](https://github.com/can1357/oh-my-pi/pull/8840) by [@Jaaneek](https://github.com/Jaaneek)).
+### Changed
+
+- The `read` tool now materializes a local text file once per invocation instead of once per consumer. A ranged read of a file within the snapshot cap previously cost four opens and three UTF-8 decodes — an 8KiB binary sniff, a streaming scan for the rendered window, a whole-file read for bracket context, and another whole-file read to hash the snapshot — with two of those readers separately normalizing line endings; whole-file reads under the structural summarizer paid a fifth read. Byte counts and truncation boundaries are now measured on the buffered bytes, so they stay exact for content that is not valid UTF-8. Files above the snapshot cap keep streaming, since nothing on that path wants the whole file. Raw reads, which skip the tree-sitter parse that dominates other reads, are 30-45% faster (2.7MB file: 10.3ms to 5.7ms).
+
+### Fixed
+
+- Fixed a whole-file `read` of a file with a UTF-8 BOM minting a hashline tag hashed from BOM-bearing text. Because the patcher's live read strips the BOM, the next edit to that file only applied through stale-hash recovery and reported that the file had changed externally when it had not.
 
 ## [17.3.6] - 2026-08-17
 
diff --git a/packages/utils/CHANGELOG.md b/packages/utils/CHANGELOG.md
index a1ca33818..8d67d0fec 100644
--- a/packages/utils/CHANGELOG.md
+++ b/packages/utils/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Added
+
+- Exported `BINARY_SNIFF_BYTES`, the header window `isProbablyBinary` sniffs, so a caller holding the whole file in memory can classify the identical prefix through `isProbablyBinaryHeader` instead of reopening the file.
+
 ## [17.3.5] - 2026-08-16
 
 ### Fixed