fix: handle gzip-compressed responses in toolbar injection #24

JacobCoffee · 2025-12-28T03:19:25Z

Summary

Fixed toolbar injection failing when responses are gzip-compressed
The middleware now detects and decompresses gzip responses before injecting toolbar HTML
Returns uncompressed response with toolbar visible

Problem

When Litestar's compression middleware runs before the debug toolbar middleware, the response body is gzip bytes. The _inject_toolbar method tried to decode this as UTF-8, which failed silently, returning the original compressed body without the toolbar injected.

This caused the toolbar to not appear on any pages when compression was enabled (which is the default in many production-like configurations).

Solution

Check for content-encoding: gzip header
Decompress the response body using gzip.decompress()
Inject toolbar HTML into the decompressed content
Strip content-encoding header (return uncompressed)
Update content-length header accordingly

Test plan

Added TestGzipCompression test class with 2 tests
Verified existing 571 tests still pass
Manually tested with shortlist-app admin pages

🤖 Generated with Claude Code

The debug toolbar middleware was failing to inject the toolbar HTML into gzip-compressed responses. When Litestar's compression middleware runs before the debug toolbar, the response body is gzip bytes, which cannot be decoded as UTF-8. The middleware silently returned the original body without injection. This fix: - Detects gzip content-encoding header - Decompresses the response body before injection - Injects the toolbar HTML into the decompressed HTML - Returns uncompressed response (strips content-encoding header) This ensures the toolbar is visible when compression is enabled, which is the default in many production-like configurations. Fixes toolbar not appearing on admin pages when compression is enabled. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

github-actions · 2025-12-28T03:21:18Z

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Pull request overview

This PR fixes a bug where the debug toolbar failed to appear on pages when gzip compression was enabled. The middleware now detects gzip-compressed responses, decompresses them before injecting the toolbar HTML, and returns an uncompressed response with the toolbar visible.

Key Changes:

Modified _inject_toolbar to handle gzip-compressed responses by decompressing before injection
Updated method signature to return a tuple of (body, content_encoding) to track encoding state
Added logic to strip the content-encoding header when returning decompressed responses

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 6 comments.

File	Description
`src/debug_toolbar/litestar/middleware.py`	Added gzip decompression logic to `_inject_toolbar` method, updated return type to tuple, and modified header handling to strip content-encoding when decompressing
`tests/integration/test_litestar_middleware.py`	Added `TestGzipCompression` test class with tests for gzip-compressed and uncompressed responses

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tests/integration/test_litestar_middleware.py

src/debug_toolbar/litestar/middleware.py

Copilot · 2025-12-28T03:25:13Z

@JacobCoffee I've opened a new pull request, #25, to work on those changes. Once the pull request is ready, I'll request review from you.

Copilot · 2025-12-28T03:25:16Z

@JacobCoffee I've opened a new pull request, #26, to work on those changes. Once the pull request is ready, I'll request review from you.

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Copilot · 2025-12-28T03:25:21Z

@JacobCoffee I've opened a new pull request, #27, to work on those changes. Once the pull request is ready, I'll request review from you.

Copilot · 2025-12-28T03:25:35Z

@JacobCoffee I've opened a new pull request, #28, to work on those changes. Once the pull request is ready, I'll request review from you.

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Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

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tests/integration/test_litestar_middleware.py

The `is_gzipped` variable was ambiguous - it initially tracked whether the header indicated gzip encoding, but then was repurposed to track whether decompression succeeded. This made the code harder to understand. Renamed to `decompressed` to explicitly indicate it tracks whether we successfully decompressed the body. This makes the logic clearer: - If decompression succeeds and UTF-8 decoding fails, return the decompressed body with no content-encoding header - If decompression fails and UTF-8 decoding fails, return the original body with the original content-encoding header Addresses feedback: #24 (comment) Co-authored-by: JacobCoffee <45884264+JacobCoffee@users.noreply.github.com>

Co-authored-by: JacobCoffee <45884264+JacobCoffee@users.noreply.github.com> Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>

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Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

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src/debug_toolbar/litestar/middleware.py

tests/integration/test_litestar_middleware.py

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

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src/debug_toolbar/litestar/middleware.py

tests/integration/test_litestar_middleware.py

src/debug_toolbar/litestar/middleware.py

Copilot · 2025-12-28T03:41:19Z

@JacobCoffee I've opened a new pull request, #29, to work on those changes. Once the pull request is ready, I'll request review from you.

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

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Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

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src/debug_toolbar/litestar/middleware.py

tests/integration/test_litestar_middleware.py

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Copilot · 2025-12-28T04:08:21Z

@JacobCoffee I've opened a new pull request, #30, to work on those changes. Once the pull request is ready, I'll request review from you.

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Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

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Copilot · 2025-12-28T04:10:10Z

src/debug_toolbar/litestar/middleware.py

+            # Can't decode. If we successfully decompressed gzip, return the
+            # decompressed body with no content-encoding. Otherwise, return
+            # the body as-is with the original encoding.
+            if decompressed:
+                return body, ""
+            return body, content_encoding


When decompression succeeds but UTF-8 decoding fails, the code returns decompressed binary data with no content-encoding header. This violates HTTP semantics because the client originally sent Accept-Encoding indicating it can handle compression, but now receives uncompressed binary data. This could break clients that expect the data format they requested. Consider returning the original compressed body with the original content-encoding header when toolbar injection isn't possible.

@copilot open a new pull request to apply changes based on this feedback

tests/integration/test_litestar_middleware.py

Copilot · 2025-12-28T04:11:42Z

@JacobCoffee I've opened a new pull request, #31, to work on those changes. Once the pull request is ready, I'll request review from you.

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Move gzip import to module level in middleware #25

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[WIP] Fix gzip handling in toolbar injection based on feedback #26

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Clarify content-encoding comment applies to all toolbar injections #27

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Refactor gzip decompression flag to explicitly track success state #28

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Copilot AI and others added 2 commits December 27, 2025 21:31

Clarify content-encoding comment applies to all toolbar injections (#27)

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[WIP] Fix gzip handling in toolbar injection based on feedback (#26)

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Co-authored-by: JacobCoffee <45884264+JacobCoffee@users.noreply.github.com> Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>

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Copilot AI added 2 commits December 27, 2025 21:36

Refactor gzip decompression flag to explicitly track success state (#28)

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Move gzip import to module level in middleware (#25)

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Copilot AI review requested due to automatic review settings December 28, 2025 03:36

Update tests/integration/test_litestar_middleware.py

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Update tests/integration/test_litestar_middleware.py

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Provide issue template for additional compression format support #29

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Add support for deflate, brotli, and zstd compression formats #30

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Fix gzip response handling to preserve HTTP semantics on decode failure #31

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JacobCoffee deleted the fix/gzip-compression-injection branch December 28, 2025 04:11

fix: handle gzip-compressed responses in toolbar injection #24

fix: handle gzip-compressed responses in toolbar injection #24

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JacobCoffee commented Dec 28, 2025

Summary

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Solution

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