Eglot inserts rest of completion twice

[accelbread]

Hi, I'm having trouble debugging an issue I am facing with corfu.

When I have text "ab" with available completion "abcd" and I hit TAB (corfu-complete), I end up with "abcdcd" instead of "abcd" with the cursor between the "cd"s (i.e.: "abcd|cd"). It is visible that the first insertion happens before the cursor and then the second after the cursor.

This occurs with the Eglot capf but not with cape-dabbrev or cape-file. I have not tested others.

This only happens with TAB (corfu-complete), but not with RET (corfu-insert).

I've tested with orderless and without, happens in both cases.

I am on Emacs 29.

Is there other steps I should take to debug this issue or is there more information that would be helpful?

[minad]

Hi, can you please provide a precise recipe starting from emacs -Q which demonstrates the issue? Also make sure that everything is configured properly, see https://github.com/minad/corfu/wiki#configuring-corfu-for-eglot.

Which precise version of Corfu do you use? Maybe this behavior has been introduced recently, in particular by 7ea1e42? Please check if this behavior also happens with the cache buster:

(advice-add 'eglot-completion-at-point :around #'cape-wrap-buster)

[WeissP]

Okay, after a few hours boring experiments, I have found the line you mentioned above is exactly the source of the bug..., i.e.:

(advice-add 'eglot-completion-at-point :around #'cape-wrap-buster) 

Steps to reproduce the bug:

1. run emacs --load "test.el" -q, where the content of test.el is:

(package-activate-all)

(setq
 corfu-cycle t
 corfu-auto t
 corfu-auto-delay 0.1
 corfu-preselect 'prompt
 )

(require 'direnv)
(require 'corfu)
(require 'cape)
(require 'eglot)

(find-file "xxx.scala")

(direnv-update-directory-environment)
(call-interactively 'eglot)

;; The line that triggers the bug!
(advice-add 'eglot-completion-at-point :around #'cape-wrap-buster) 

(setq completion-at-point-functions '(eglot-completion-at-point nil))

(global-corfu-mode)

You can ignore all the lines related to direnv, they are just used to get necessary external dependencies, such as the language server.

2. Type imp and wait for the completion candidate "import" to appear. However, do not complete it. Instead, continue typing ort. After typing t (the last character of import), you will notice that it becomes import ort, meaning that ort appears twice.

[minad]

Thanks. Maybe minad/cape@86c5bdf helps? You can also try cape-capf-debug to analyze the Capf call sequence:

(setq completion-at-point-functions (list (cape-capf-buster (cape-capf-debug #'eglot-completion-at-point))))

I suspect that the problem lies somewhere in the :exit-function, which has difficulties applying the correct edits to the completion result. I appreciate help fixing this.

[WeissP]

Okay I am a little bit confused now...
So first of all using minad/cape@86c5bdf doesn't help, then I changed completion-at-point-functions to this:

(setq completion-at-point-functions (list (cape-capf-buster (cape-capf-debug #'eglot-completion-at-point))))

But then there are no more issues...,in other words, this line will cause the issue:

(setq completion-at-point-functions (list (cape-capf-buster #'eglot-completion-at-point)))

But if it is wrapped with cape-capf-debug, there will be no more issues.

But anyway here is the log:

company-deprecated=#<function> company-docsig=#<function> company-doc-buffer=#<function> company-require-match=never company-prefix-length=nil exit-function=#<function>
eglot-completion-at-point@2 => input=23:26:"imp" table=(#("import" 0 1 (eglot--lsp-item ...)) #("implicit" 0 1 (eglot--lsp-item ...))) annotation-function=#<function> company-kind=#<function> company-deprecated=#<function> company-docsig=#<function> company-doc-buffer=#<function> company-require-match=never company-prefix-length=nil exit-function=#<function>
eglot-completion-at-point@2(action=metadata input=23:26:"imp" prefix="imp" ignore-case=nil) => (metadata (category . eglot-capf) (display-sort-function . #<subr F616e6f6e796d6f75732d6c616d626461_anonymous_lambda_158>))
eglot-completion-at-point@2(action=(boundaries . "") input=23:26:"imp" prefix="imp" ignore-case=nil) => nil
eglot-completion-at-point@2(action=all input=23:26:"imp" prefix="imp" ignore-case=nil) => (#("import" 0 1 (face completions-common-part eglot--lsp-item ...) 1 2 (face completions-common-part) 2 3 (face completions-common-part)) #("implicit" 0 1 (face completions-common-part eglot--lsp-item ...) 1 2 (face completions-common-part) 2 3 (face completions-common-part)))
eglot-completion-at-point@3 => input=23:27:"impo" table=nil annotation-function=#<function> company-kind=#<function> company-deprecated=#<function> company-docsig=#<function> company-doc-buffer=#<function> company-require-match=never company-prefix-length=nil exit-function=#<function>
eglot-completion-at-point@4 => input=23:28:"impor" table=nil annotation-function=#<function> company-kind=#<function> company-deprecated=#<function> company-docsig=#<function> company-doc-buffer=#<function> company-require-match=never company-prefix-length=nil exit-function=#<function>
eglot-completion-at-point@5 => input=23:29:"import" table=(#("import" 0 1 (eglot--lsp-item ...))) annotation-function=#<function> company-kind=#<function> company-deprecated=#<function> company-docsig=#<function> company-doc-buffer=#<function> company-require-match=never company-prefix-length=nil exit-function=#<function>
eglot-completion-at-point@2(action=metadata input=23:29:"import" prefix="import" ignore-case=nil) => (metadata (category . eglot-capf) (display-sort-function . #<subr F616e6f6e796d6f75732d6c616d626461_anonymous_lambda_158>))
eglot-completion-at-point@2(action=(boundaries . "") input=23:29:"import" prefix="import" ignore-case=nil) => nil
eglot-completion-at-point@6 => input=23:29:"import" table=(#("import" 0 1 (eglot--lsp-item ...))) annotation-function=#<function> company-kind=#<function> company-deprecated=#<function> company-docsig=#<function> company-doc-buffer=#<function> company-require-match=never company-prefix-length=nil exit-function=#<function>
eglot-completion-at-point@6(action=all input=23:29:"import" prefix="import" ignore-case=nil) => (#("import" 0 1 (face completions-common-part eglot--lsp-item ...) 1 2 (face completions-common-part) 2 3 (face completions-common-part) 3 4 (face completions-common-part) 4 5 (face completions-common-part) 5 6 (face completions-common-part)))
eglot-completion-at-point@6(action=(boundaries . "") input=23:29:"import" prefix="import" ignore-case=nil) => nil
eglot-completion-at-point@6(action=try input=23:29:"import" prefix="import" ignore-case=nil) => t
eglot-completion-at-point@6:exit(candidate=#("import" 0 1 (face completions-common-part eglot--lsp-item (:label #0 :kind 14 :tags [] :detail "" :sortText "00000" :filterText #("import" 0 1 (face completions-common-part) 1 2 (face completions-common-part) 2 3 (face completions-common-part) 3 4 (face completions-common-part) 4 5 (face completions-common-part) 5 6 (face completions-common-part)) :insertTextFormat 2 :textEdit (:range (:start (:line 1 :character 0) :end (:line 1 :character 6)) :newText "import ") :additionalTextEdits [])) 1 2 (face completions-common-part) 2 3 (face completions-common-part) 3 4 (face completions-common-part) 4 5 (face completions-common-part) 5 6 (face completions-common-part)) status=finished)
eglot-completion-at-point@7 => input=30:30:"" table=(#("Channel com.jb.domain" 0 1 (eglot--lsp-item ...)) #("ChannelInfo com.jb.domain" 0 1 (eglot--lsp-item ...)) #("ChannelMeta com.jb.domain" 0 1 (eglot--lsp-item ...)) #("Continuation" 0 1 (eglot--lsp-item ...)) #("Continuation com.jb.domain" 0 1 (eglot--lsp-item ...)) ...) annotation-function=#<function> company-kind=#<function> company-deprecated=#<function> company-docsig=#<function> company-doc-buffer=#<function> company-require-match=never company-prefix-length=nil exit-function=#<function>
Making completion list...

[minad]

In your log, it is suspicious that the Capf doesn't always coherently return candidates. Note the table=nil:

eglot-completion-at-point@3 => input=23:27:"impo" table=nil annotation-function=#<function> company-kind=#<function> company-deprecated=#<function> company-docsig=#<function> company-doc-buffer=#<function> company-require-match=never company-prefix-length=nil exit-function=#<function>
eglot-completion-at-point@4 => input=23:28:"impor" table=nil annotation-function=#<function> company-kind=#<function> company-deprecated=#<function> company-docsig=#<function> company-doc-buffer=#<function> company-require-match=never company-prefix-length=nil exit-function=#<function>

Retrieving the candidates from the backend during debugging could also have a side effect. You can try commenting the all-completions call out to see if it makes a difference: https://github.com/minad/cape/blob/86c5bdfc5c3ea1148a827702224190a70250c656/cape.el#L951-L956

[ksqsf]

This problem happened to me as well. The following trace was obtained using (setq completion-at-point-functions (list (cape-capf-buster (cape-capf-debug #'eglot-completion-at-point))))

In my test case, I typed mana in a Rust buffer, and then the Corfu automatically shows a candidate list where the first candidate is manager, and then I press TAB to commit the candidate. The final result is unfortunately the incorrect managerger.

And I can also confirmed that by removing cache-buster this problem disappears.

eglot-completion-at-point@15 => input=532:536:"mana" table=(#("Manager (use manager::Manager)" 0 1 (eglot--lsp-item ...)) #("_mm256_aesenclast_epi128 (use std::arch::x86_64::_mm256_aesenclast_epi128)" 0 1 (eglot--lsp-item ...)) #("_mm256_mask3_fnmadd_pd (use std::arch::x86_64::_mm256_mask3_fnmadd_pd)" 0 1 (eglot--lsp-item ...)) #("_mm256_mask3_fnmadd_ps (use std::arch::x86_64::_mm256_mask3_fnmadd_ps)" 0 1 (eglot--lsp-item ...)) #("_mm256_mask_cmpneq_epi16_mask (use std::arch::x86_64::_mm256_mask_cmpneq_epi16_mask)" 0 1 (eglot--lsp-item ...)) ...) cape--buster=t annotation-function=#<function> company-kind=#<function> company-deprecated=#<function> company-docsig=#<function> company-doc-buffer=#<function> company-require-match=never company-prefix-length=nil exit-function=#<function>
eglot-completion-at-point@15(action=metadata input=532:536:"mana" prefix="mana" ignore-case=nil) => (metadata (category . eglot) (display-sort-function . #[257 "\300�\301\302\303$\207" [cl-sort string-lessp :key #[257 "\300\301\302\303�#\304\"\207" [plist-get get-text-property 0 eglot--lsp-item :sortText] 6 "

(fn C)"]] 6 "

(fn COMPLETIONS)"]))
eglot-completion-at-point@15(action=(boundaries . "") input=532:536:"mana" prefix="mana" ignore-case=nil) => nil [2 times]
eglot-completion-at-point@15(action=all input=532:536:"mana" prefix="" ignore-case=nil regexp=("\\`.*?m.*?a.*?n.*?a")) => (#("Manager (use manager::Manager)" 0 1 (eglot--lsp-item ...)) #("_mm256_aesenclast_epi128 (use std::arch::x86_64::_mm256_aesenclast_epi128)" 0 1 (eglot--lsp-item ...)) #("_mm256_mask3_fnmadd_pd (use std::arch::x86_64::_mm256_mask3_fnmadd_pd)" 0 1 (eglot--lsp-item ...)) #("_mm256_mask3_fnmadd_ps (use std::arch::x86_64::_mm256_mask3_fnmadd_ps)" 0 1 (eglot--lsp-item ...)) #("_mm256_mask_cmpneq_epi16_mask (use std::arch::x86_64::_mm256_mask_cmpneq_epi16_mask)" 0 1 (eglot--lsp-item ...)) ...)
eglot-completion-at-point@15(action=test input=532:536:"mana" prefix="mana" ignore-case=nil) => nil
eglot-completion-at-point@15(action=test input=532:539:"manager" prefix=#("manager" 0 1 (eglot--lsp-item (:label #("manager" 0 1 (eglot--lsp-item #2)) :kind 6 :detail "Manager" :deprecated :json-false :preselect t :sortText "ffffffee" :filterText "manager" :textEdit (:range (:start (:line 28 :character 4) :end (:line 28 :character 8)) :newText "manager") :additionalTextEdits []) face completions-common-part completion-score 0.5714285714285714) 1 2 (face completions-common-part) 2 3 (face completions-common-part) 3 4 (face completions-common-part) 4 5 (face completions-first-difference)) ignore-case=nil) => t
eglot-completion-at-point@15(action=metadata input=532:539:"manager" prefix=#("manager" 0 1 (eglot--lsp-item (:label #("manager" 0 1 (eglot--lsp-item #2)) :kind 6 :detail "Manager" :deprecated :json-false :preselect t :sortText "ffffffee" :filterText "manager" :textEdit (:range (:start (:line 28 :character 4) :end (:line 28 :character 8)) :newText "manager") :additionalTextEdits []) face completions-common-part completion-score 0.5714285714285714) 1 2 (face completions-common-part) 2 3 (face completions-common-part) 3 4 (face completions-common-part) 4 5 (face completions-first-difference)) ignore-case=nil) => (metadata (category . eglot) (display-sort-function . #[257 "\300�\301\302\303$\207" [cl-sort string-lessp :key #[257 "\300\301\302\303�#\304\"\207" [plist-get get-text-property 0 eglot--lsp-item :sortText] 6 "

(fn C)"]] 6 "

(fn COMPLETIONS)"]))
eglot-completion-at-point@15(action=(boundaries . "") input=532:539:"manager" prefix=#("manager" 0 1 (completion-score 0.5714285714285714 face completions-common-part eglot--lsp-item (:label #("manager" 0 1 (eglot--lsp-item #2)) :kind 6 :detail "Manager" :deprecated :json-false :preselect t :sortText "ffffffee" :filterText "manager" :textEdit (:range (:start (:line 28 :character 4) :end (:line 28 :character 8)) :newText "manager") :additionalTextEdits [])) 1 2 (face completions-common-part) 2 3 (face completions-common-part) 3 4 (face completions-common-part) 4 5 (face completions-first-difference)) ignore-case=nil) => nil
eglot-completion-at-point@16 => input=532:539:"manager" table=(#("Manager (use manager::Manager)" 0 1 (eglot--lsp-item ...)) #("self::" 0 1 (eglot--lsp-item ...)) #("crate::" 0 1 (eglot--lsp-item ...)) #("manager" 0 1 (eglot--lsp-item ...)) #("manager" 0 1 (eglot--lsp-item ...)) ...) cape--buster=t annotation-function=#<function> company-kind=#<function> company-deprecated=#<function> company-docsig=#<function> company-doc-buffer=#<function> company-require-match=never company-prefix-length=nil exit-function=#<function>
eglot-completion-at-point@16(action=all input=532:539:"manager" prefix="" ignore-case=nil regexp=("\\`.*?m.*?a.*?n.*?a.*?g.*?e.*?r")) => (#("Manager (use manager::Manager)" 0 1 (eglot--lsp-item ...)) #("manager" 0 1 (eglot--lsp-item ...)) #("manager" 0 1 (eglot--lsp-item ...)))
eglot-completion-at-point@16(action=(boundaries . "") input=532:539:"manager" prefix=#("manager" 0 1 (eglot--lsp-item (:label #("manager" 0 1 (eglot--lsp-item #2)) :kind 6 :detail "Manager" :deprecated :json-false :preselect t :sortText "ffffffee" :filterText "manager" :textEdit (:range (:start (:line 28 :character 4) :end (:line 28 :character 8)) :newText "manager") :additionalTextEdits []) face completions-common-part completion-score 0.5714285714285714) 1 2 (face completions-common-part) 2 3 (face completions-common-part) 3 4 (face completions-common-part) 4 5 (face completions-first-difference)) ignore-case=nil) => nil
eglot-completion-at-point@16:exit(candidate=#("manager" 0 1 (eglot--lsp-item (:label #("manager" 0 1 (eglot--lsp-item #2)) :kind 6 :detail "Manager" :deprecated :json-false :preselect t :sortText "ffffffee" :filterText "manager" :textEdit (:range (:start (:line 28 :character 4) :end (:line 28 :character 8)) :newText "manager") :additionalTextEdits []) face completions-common-part completion-score 0.5714285714285714) 1 2 (face completions-common-part) 2 3 (face completions-common-part) 3 4 (face completions-common-part) 4 5 (face completions-first-difference)) status=finished)

[ksqsf]

Version:

• eglot, version 1.12.29 (emacs-29 branch built-in)
• Corfu: 20240103.1401 from melpa
• Cape: 20240102.2150 from melpa

[ksqsf]

Screencast:

2024-01-10.02.12.28.mov

What's strange is that the repeated 'ger' appears only after a short delay.

[ksqsf]

I trimmed the config and can reproduce the problem using the following procedure. Hopefully it will be helpful to @minad.

1. Create an empty directory named e.g. bug
2. Create a file bug/bug.el

(require 'package)
(add-to-list 'package-archives '("melpa" . "https://melpa.org/packages/") t)
(use-package rust-mode :ensure t)
(use-package cape :ensure t)
(use-package corfu :ensure t)

(global-corfu-mode t)
(setq corfu-auto t)
(advice-add 'eglot-completion-at-point :around #'cape-wrap-buster)

3. emacs --init-directory bug -l bug/bug.el
4. cd bug; cargo new rsproj to create a project at bug/rsproj
5. Open bug/rsproj/src/main.rs, move to the top of the file, and type use std::.
6. There will be a list of candidates, type TAB to complete it.

7. And this is the final result.

However, if you remove advice-add from the config above, this problem disappears.

[jdtsmith]

I've occasionally seen this, but (I think) only when completing inside an existing word with dabbrev, ala:

te[X]xt ; M-Tab ; (select text): textst

I also wrap, but only with the less aggressive cache-dumper based on string prefix:

(cape-capf-buster #'eglot-completion-at-point #'string-prefix-p)

[minad]

I've occasionally seen this, but (I think) only when completing inside an existing word with dabbrev, ala:

Completing inside a word should be a different scenario. In that scenario, the suffix behind point is never considered part of the completion. Completing inside words is fixable in Corfu, but this hasn't been requested often (Company also has a related open issue).

I also wrap, but only with the less aggressive cache-dumper based on string prefix:

In Python (iirc this is what you use the most) do you see the described behavior for any of these three settings:

1. (setq-local completion-at-point-functions (list #'eglot-completion-at-point))
2. (setq-local completion-at-point-functions (list (cape-capf-buster #'eglot-completion-at-point #'equal)))
3. (setq-local completion-at-point-functions (list (cape-capf-buster #'eglot-completion-at-point #'string-prefix-p)))

[jdtsmith]

No, with pyright (wrapped with eglot-booster) I do not see word-doubling with any of the options above. But note, the completion exchange in LSP is very complex, with many optional client/server capabilities, etc. My pyright request/replies look like the below. Perhaps other servers implement fancier completions with textEdit or insertText properties? I.e. their servers are too smart for eglot/corfu. Check the M-x eglot-events-buffer and compare your completion messages.

[client-request] (id:84) Fri Jan 12 11:52:37 2024:
(:jsonrpc "2.0" :id 84 :method "textDocument/completion" :params
	  (:textDocument
	   (:uri "file:///Users/jdsmith/code/python/test/test_axes.py")
	   :position
	   (:line 9897 :character 7)
	   :context
	   (:triggerKind 2 :triggerCharacter ".")))
[server-reply] (id:84) Fri Jan 12 11:52:37 2024:
(:id 84 :jsonrpc "2.0" :result
     (:isIncomplete t :items
		    [(:data
		      (:filePath "/Users/jdsmith/code/python/test/test_axes.py" :funcParensDisabled t :position
				 (:character 7 :line 9897)
				 :symbolLabel "__name__" :workspacePath "/Users/jdsmith/code/python/test")
		      :kind 6 :label "__name__" :sortText "11.9999.__name__")
		     (:data
		      (:filePath "/Users/jdsmith/code/python/test/test_axes.py" :funcParensDisabled t :position
				 (:character 7 :line 9897)
				 :symbolLabel "__qualname__" :workspacePath "/Users/jdsmith/code/python/test")
		      :kind 6 :label "__qualname__" :sortText "11.9999.__qualname__")
		     (:data
		      (:filePath "/Users/jdsmith/code/python/test/test_axes.py" :funcParensDisabled t :position
				 (:character 7 :line 9897)
				 :symbolLabel "__loader__" :workspacePath "/Users/jdsmith/code/python/test")
		      :kind 6 :label "__loader__" :sortText "11.9999.__loader__")
		     (:data
		      (:filePath "/Users/jdsmith/code/python/test/test_axes.py" :funcParensDisabled t :position
				 (:character 7 :line 9897)
				 :symbolLabel "__package__" :workspacePath "/Users/jdsmith/code/python/test")
		      :kind 6 :label "__package__" :sortText "11.9999.__package__")
		     (:data
		      (:filePath "/Users/jdsmith/code/python/test/test_axes.py" :funcParensDisabled t :position
				 (:character 7 :line 9897)
				 :symbolLabel "__spec__" :workspacePath "/Users/jdsmith/code/python/test")
		      :kind 6 :label "__spec__" :sortText "11.9999.__spec__")
		     (:data
		      (:filePath "/Users/jdsmith/code/python/test/test_axes.py" :funcParensDisabled t :position
				 (:character 7 :line 9897)
				 :symbolLabel "__path__" :workspacePath "/Users/jdsmith/code/python/test")
		      :kind 6 :label "__path__" :sortText "11.9999.__path__")
                      ...

and then on select, a resolve request is a sent, which gives some doc and other info:

[client-request] (id:88) Fri Jan 12 11:52:40 2024:
(:jsonrpc "2.0" :id 88 :method "completionItem/resolve" :params
	  (:data
	   (:filePath "/Users/jdsmith/code/python/test/test_axes.py" :funcParensDisabled t :position ... :symbolLabel
		      #("format_float_positional" 0 1 ...)
		      :workspacePath "/Users/jdsmith/code/python/test")
	   :kind 3 :label
	   #("format_float_positional" 0 1 ...)
	   :sortText "05.0000.format_float_positional"))
[server-reply] (id:88) Fri Jan 12 11:52:40 2024:
(:id 88 :jsonrpc "2.0" :result
     (:data
      (:filePath "/Users/jdsmith/code/python/test/test_axes.py" :funcParensDisabled t :position ... :symbolLabel "format_float_positional" :workspacePath "/Users/jdsmith/code/python/test")
      :documentation
      (:kind "plaintext" :value "def format_float_positional(\n    x: _FloatLike_co,\n    precision: int | None = ...,\n    unique: bool = ...,\n    fractional: bool = ...,\n    trim: Literal['k', '.', '0', '-'] = ...,\n    sign: bool = ...,\n    pad_left: int | None = ...,\n    pad_right: int | None = ...,\n    min_digits: int | None = ...\n) -> str\n\nFormat a floating-point scalar as a decimal string in positional notation.\n\nProvides control over rounding, trimming and padding. Uses and assumes\nIEEE unbiased rounding. Uses the \"Dragon4\" algorithm.\n\nParameters\n----------\nx : python float or numpy floating scalar\n    Value to format.\nprecision : non-negative integer or None, optional\n    Maximum number of digits to print. May be None if `unique` is\n    `True`, but must be an integer if unique is `False`.\nunique : boolean, optional\n    If `True`, use a digit-generation strategy which gives the shortest\n    representation which uniquely identifies the floating-point number from\n    other values of the same type, by judicious rounding. If `precision`\n    is given fewer digits than necessary can be printed, or if `min_digits`\n    is given more can be printed, in which cases the last digit is rounded\n    with unbiased rounding.\n    I
....

[minad]

Thanks. I know that behind the scenes the completion protocol is quite complex. But all of this is one level below the Corfu/Cape level. What is interesting here in particular is why the cache buster makes a difference, in the case of a server returning such more complex text edit properties.

[jdtsmith]

I don't know the details, but I could (vaguely) imagine a scenario where eglot wanted its table function to have stuck around in this context so it could complete the fancy completion edit/insertion. And maybe company accommodates that, and the capf-buster does not, so the edit doesn't occur.

Step 1 I think is to see whether the flavor of completion response from the server differs.

[mekeor]

• I duplicated this bug report here: orderless completion style together with cape-wrap-buster for eglot, leads to duplicate insertion of completion #415
• @minad, do you want us to test the following lines with or without the advice enabled?

(setq-local completion-at-point-functions (list #'eglot-completion-at-point))
(setq-local completion-at-point-functions (list (cape-capf-buster #'eglot-completion-at-point)))
(setq-local completion-at-point-functions (list (cape-capf-buster (cape-capf-debug #'eglot-completion-at-point))))
(setq-local completion-at-point-functions (list (cape-capf-buster #'eglot-completion-at-point #'equal)))
(setq-local completion-at-point-functions (list (cape-capf-buster #'eglot-completion-at-point #'string-prefix-p)))

[minad]

These lines should be tested and analyzed without the advice. Please look at the code to see what is going on. cape-wrap-buster and cape-capf-buster are essentially the same. The cape-wrap-buster can be used as advice and cape-capf-buster is a Capf builder.

In order to make progress we need a detailed analysis, maybe also debugging the Capf and the :exit-function. See also what @jdtsmith wrote here: #400 (reply in thread)

[jdtsmith]

I still advise checking the eglot events buffer as I mentioned above, and comparing the content of the textDocument/completion the server provides, to the example. If it's an identical type of request/response sequence, it's less likely that the problem is related to variations in how eglot needs to treat completions.

[minad]

See https://debbugs.gnu.org/cgi/bugreport.cgi?bug=72765