New Features

• Send workspace folders (rootUri and workspaceFolders) during LSP initialization and dynamically notify the server when new project roots are encountered. This improves suggestion quality for multi-root workspaces.
• Add copilot-completion-model option and copilot-select-completion-model command for choosing the AI model used for completions. (#382)
• Add copilot-enable-parentheses-balancer option to control whether Lisp completions are post-processed for balanced delimiters (enabled by default).
• Add copilot-accept-completion-by-sentence command.
• Add copilot-accept-completion-up-to-char and copilot-accept-completion-to-char commands, similar to zap-up-to-char and zap-to-char.
• Add copilot-clear-overlay-on-commands user option to clear the overlay before specific commands (e.g. beginning-of-visual-line).
• Handle window/showMessageRequest server requests via completing-read and window/showDocument to open URIs in the browser or Emacs.
• Handle didChangeStatus server notifications to show Copilot status (Normal, Warning, Error, Inactive) in the mode-line.
• Handle $/progress server notifications to display progress for long-running operations (e.g. indexing) in the mode-line.
• Send $/cancelRequest when a new completion is requested or the overlay is dismissed, so the server stops working on stale in-flight requests.
• Perform a clean LSP shutdown sequence (shutdown request + exit notification) instead of just killing the server process.
• Add copilot-on-request and copilot-on-notification for user-defined handlers on incoming server messages.
• Add buttercup test infrastructure with comprehensive tests for core functionality.

Changes

• copilot--lsp-settings-changed now sends workspace/didChangeConfiguration instead of restarting the server.
• Remove unnecessary :dummy placeholder parameters from JSON-RPC requests.
• Migrate from legacy getCompletions API to standard textDocument/inlineCompletion for compatibility with newer Copilot language server versions. Adds partial acceptance telemetry via textDocument/didPartiallyAcceptCompletion.
• Rename copilot-version to copilot-lsp-server-version (copilot-version is now an obsolete alias).
• Replace the f library dependency with compat.
• Hardcode universal-argument, digit-argument, negative-argument, and universal-argument-more as commands that should not clear the overlay.
• Honor copilot-clear-overlay-ignore-commands for remapped commands (e.g. universal-argument-more).

Bug Fixes

• Rewrite copilot-balancer to use parse-partial-sexp so that parens inside comments and strings are handled correctly. (#440)
• Fix balancer dropping closing delimiters inside comments/strings when the server returns a replacement range covering them. (#449)
• Fix copilot-complete not working without copilot-mode until copilot-diagnose is run, by sending textDocument/didOpen automatically. (#450)
• Fix partial accept-by-word losing the replacement range tail, which caused suffix text to be deleted prematurely. (#448)
• Send an empty JSON object instead of omitting params in JSON-RPC requests, fixing signInInitiate and other calls on newer language server versions. (#445)
• Fix copilot--lsp-pos to use UTF-16 code unit offsets instead of Emacs character counts. Characters above U+FFFF (e.g. emoji) are now correctly reported as 2 UTF-16 code units.
• Fix textDocument/didFocus and textDocument/didOpen notification names to use plain symbols instead of keyword symbols (which were serialized with a leading colon).
• Fix PanelSolution handler to use (goto-char (point-min)) instead of (call-interactively #'mark-whole-buffer), which was activating the mark and interfering with user state.
• Fix copilot--get-relative-path to use fboundp instead of boundp for checking vc-root-dir.
• Use tab-width instead of standard-indent as the fallback indentation offset for modes not in copilot-indentation-alist. (#312)
• Set priority on the copilot completion overlay to avoid conflicts with Emacs 30's completion-preview-mode. (#377)
• Filter out minibuffers and internal buffers in global-copilot-mode. (#337)
• Don't warn about copilot-max-char in temporary and non-file-visiting buffers. (#313)
• Handle events-buffer-scrollback-size deprecation in newer jsonrpc versions gracefully. (#329)
• Remove the company-mode dependency that could cause void-function company--active-p errors. (#243)
• Don't start the Copilot server in copilot--on-doc-close when the connection is not alive. (#265)
• Add linting CI job and fix checkdoc and indentation lint warnings.