Claude Code v2.1.281 · 23 Sep 2026
File tools add a new early validation step
Read, Edit, Write and NotebookEdit now run a shared check on the file path before any of their other input checks
You'll notice Tier: how much it should matter to you
1 Useful: my rating, 1 to 5
1 Signal: worth watching, 1 to 5
File Access Area: what it touches
Improvements Kind: in v2.1.281, 23 Sep 26
Improvements Section of the release
Unclear The finding does not say what the shared path check tests for.
What
The tools Claude uses to read and change files now share a new first step when they check their input. Before any of their existing checks, each one tests the path it was given, and stops with that result if the test fails. It covers:
Why
A bad path is now caught at the very start, in the same way for all four tools, before anything else about the request is looked at.
How sure we are
Something disagrees Something we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubt The finding does not say what the shared path check tests for.
See this entry in the whole of v2.1.281 →
23 Sep 2026 · 1,065 entries, this one is #374.
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Names in this entry
tool NotebookEdit Notebooks over 100 MB are refused for reads and edits, with a suggestion to slice them.
tool Read Files covered by a Read deny rule can no longer be written, not just edited.
tool Edit Edit, Write and NotebookEdit approval previews withhold the diff when the change is too large or the file can't be read
tool Write Edit, Write and NotebookEdit approval previews withhold the diff when the change is too large or the file can't be read
Is this right?
0 0 Feedback
What's wrong with this entry?
Hard to understand Too vague Looks wrong Not relevant to me Too long Missing the detail I wanted Duplicate of another card
Clear Learned something new I can act on this Good catch
Related
Other releases about the same thing. Found by shared names or similar wording; neither means one caused the other.
← Previous · 373 of 1,065
Windows credential stores added to the protected-path read-deny list
You'll notice Windows
In v2.1.281 Improvements release-page order
Next → · 375 of 1,065
Windows CONIN$/CONOUT$ names rejected as path segments and working names
You'll notice Windows
