Built-in git blame editor decorations are not applied when diff editor is opened via third-party extension (e.g. Git Graph / GitLens)

Type: Bug

Description / Problem:
The built-in git blame decoration feature (adding line blame info) in VS Code does not work when a diff editor is opened by a third-party extension (such as Git Graph or GitLens). When using VS Code’s own Source Control Graph to open diffs, blame decorations appear and work as expected.

Reproduction steps:

1. Use VS Code Insiders 1.107.0-insider on Windows (or any recent version).
2. Ensure "git.blame.editorDecoration.enabled": true.
3. Use a third-party git / history extension (e.g. Git Graph, GitLens), open commit history, and open a file diff via the extension.
4. In the diff editor, click on lines on either side of the diff.

Observed behavior:

• No blame editor decorations (nor blame status-bar item) appear.

Expected behavior:

• According to the built-in git blame support, blame annotations / decorations should appear in the diff editor, regardless of how the diff was opened (built-in or via extension).

Relevant background & existing issues:

• Blame-decoration functionality was formally added in the release notes for January 2025 (version 1.97).
• The feature was tested under the issue Test: Git blame editor decoration/status bar it (#235028), which includes diff-editor use (working tree and staged changes) in its test plan.
• There is a known bug Git Blame - editor decoration appears incorrectly (#235030) describing that “dirty diff decorations” use a legacy diff algorithm, while the diff editor uses an “advanced diff algorithm,” which in some edge cases leads to mismatched decoration results.
• However, none of the existing issues explicitly mention diff editors opened via third-party extensions or handle extension-driven diffs.

Why this matters / Use case:
Many developers — myself included — use extensions like Git Graph or GitLens to inspect history and open diffs. If built-in blame decorations only work when diffs are opened via the built-in Source Control Graph, that significantly reduces the utility of blame in real-world workflows.

Request / Ask:

• Please verify whether the blame-decoration logic in VS Code supports diff editors invoked by third-party extensions.
• If not, consider updating the logic so that blame decorations are applied in diff editors regardless of how they are opened (built-in or third-party).
• If there is a limitation or known restriction, please document it so extension authors and users are aware.

Thank you for your continued work on git integration in VS Code!

Version information:

VS Code: 1.107.0-insider (commit fae32c4c21fc40c9caaf480b4f7f28ca077a2be6)  
Git Graph: 1.31.5  
OS: Windows 11
Git: 2.45.1.windows.1  
Settings: git.blame.editorDecoration.enabled = true  
          git.blame.editorDecoration.template = "${authorName}, ${authorDateAgo} • ${subject}"

Item	Value
CPUs	AMD Ryzen 5 3600XT 6-Core Processor (12 x 3793)
GPU Status	2d_canvas: enableddirect_rendering_display_compositor: disabled_off_okgpu_compositing: enabledmultiple_raster_threads: enabled_onopengl: enabled_onrasterization: enabledraw_draw: disabled_off_okskia_graphite: disabled_offtrees_in_viz: disabled_offvideo_decode: enabledvideo_encode: enabledwebgl: enabledwebgl2: enabledwebgpu: enabledwebnn: disabled_off
Load (avg)	undefined
Memory (System)	63.93GB (41.08GB free)
Process Argv
Screen Reader	no
VM	0%

Extension	Author (truncated)	Version
monokai-charcoal-high-contrast	74t	3.5.0
better-comments	aar	3.0.2
calculate	aca	2.1.0
format-selection-as-html	adr	2.3.0
vscode-javascript-snippet-pack	aka	0.1.6
increment-selection	alb	0.2.0
Bookmarks	ale	13.5.0
json-lines-editor	Ano	0.1.0
launch-config	Art	0.9.0
jsonyamlkeynavigator	b-s	0.4.0
vscode-autohotkey-ahkdoc	bhb	0.5.2
unique-lines	bib	1.0.0
markdown-footnotes	bie	0.1.1
xml2json	bui	1.2.5
vscode-better-align	cho	1.4.4
npm-intellisense	chr	1.4.5
path-intellisense	chr	2.10.0
gotoanything	Cma	0.4.1
column-jump	Cod	0.0.7
codesandbox-projects	Cod	0.2.143
vscode-clock	Com	0.0.1
xpathtester	cre	1.2.0
dakara-foldplus	dak	1.5.2
transformer	dak	1.12.1
join-lines-into-columns	dav	0.0.2
tsservercontrols	dav	1.1.0
vscode-quick-select	dba	0.2.9
jquerysnippets	don	0.0.1
xml	Dot	2.5.1
es7-react-js-snippets	dsz	4.4.3
gitlens	eam	17.7.1
EditorConfig	Edi	0.17.4
json-tools	eri	1.0.2
prettier-vscode	esb	11.0.2
decapsulator	fit	1.0.2
shell-format	fox	7.2.8
copilot-chat	Git	0.34.2025120301
vscode-pull-request-github	Git	0.123.2025120304
todo-tree	Gru	0.0.226
git-graph-2	han	1.31.5
vscode-settings-cycler	hoo	1.0.1
output-colorizer	IBM	0.1.2
vscode-jsp-clone	J0h	0.0.6
i18next	jac	0.7.2
search-ignore-whitespace	jak	0.0.1
vscode-edit-csv	jan	0.11.8
search-node-modules	jas	1.3.0
better-shellscript-syntax	jef	1.10.0
vs-docblock	jer	1.6.1
tabstronaut	jhh	1.4.0
dupchecker	jia	0.1.7
select-matches-or-adjust-selection	joh	0.10.4
vscode-peacock	joh	4.2.2
minifyall	jos	2.10.0
vsc-python-indent	Kev	1.21.0
conditional-format	KMR	1.3.0
labeled-bookmarks	koa	1.1.11
wrapSelection	kon	0.10.0
expand-region	let	0.1.4
vscode-plugin-keyboard-shortcut-eval-custom-javascript-codes	Lia	1.0.13
highlight-duplicates	Lor	1.1.1
bash-ide-vscode	mad	1.43.0
code-beautifier	mic	2.3.3
vscode-edits-history	mis	0.1.6
shfmt	mkh	1.5.1
find-jump	mks	1.2.4
workspace-name-identifier	mmc	0.0.1
compare-folders	mos	0.25.3
format-selection-stub	mot	0.0.2
black-formatter	ms-	2025.2.0
debugpy	ms-	2025.16.0
isort	ms-	2025.0.0
python	ms-	2025.18.0
vscode-pylance	ms-	2025.10.3
vscode-python-envs	ms-	1.13.13371014
live-server	ms-	0.5.2025091501
powershell	ms-	2025.4.0
sublime-keybindings	ms-	4.1.10
vscode-commander	ms-	0.2.0
vscode-speech	ms-	0.16.0
vscode-websearchforcopilot	ms-	0.1.2025120301
copy-file-name	nem	1.2.0
react-proptypes-intellisense	OfH	1.0.3
fix-json	oli	0.2.0
terminal-command-keys	pet	0.5.0
java	red	1.50.0
vscode-commons	red	0.0.6
vscode-rsp-ui	red	0.24.12
vscode-sort-json	ric	1.20.0
LiveServer	rit	5.7.9
bash-debug	rog	0.3.9
color-manager	roy	0.7.5
vscode-paste-and-indent	Rub	0.0.8
prettier-plugin-java-vscode	Rud	1.0.3
better-pageup-pagedown	rus	0.0.1
partial-diff	ryu	1.4.3
text-marker	ryu	1.11.0
multi-command	ryu	1.6.0
sql-snippets	sad	0.0.4
json-to-js-object	sal	0.0.4
vscode-fqn	san	1.0.3
block-travel	sas	0.0.2
preview-vscode	sea	2.3.12
vscode-sql-beautify	sen	0.0.4
docxreader	Sha	1.3.0
bash-beautify	sha	0.1.1
trailing-spaces	sha	0.4.1
markdown-preview-enhanced	shd	0.8.20
vscode-fileutils	sle	3.10.3
local-tomcat	Sne	2.1.1
sonarlint-vscode	Son	4.35.1
open-in-browser	tec	2.0.0
shellcheck	tim	0.38.5
vscode-decompiler	tin	0.1.0
duplicate-finder	tle	0.0.6
run-in-powershell	tob	1.2.0
pdf	tom	1.2.2
todo-list	Tza	1.6.0
incrementor	use	0.1.5
es-quotes	vil	0.2.6
vscode-boot-dev-pack	vmw	0.2.2
vscode-java-upgrade	vsc	1.9.1
console-ninja	Wal	1.0.500
chakra-ui-snippets	wei	0.0.6
change-case	wma	1.0.0
vsc-meta-snippet	wmo	0.1.2
bat-formatter	wwn	0.0.5
JavaScriptSnippets	xab	1.8.0
txt-syntax	xsh	0.2.4
markdown-pdf	yza	1.5.0
markdown-all-in-one	yzh	3.6.3

(10 theme extensions excluded)