Single-file session attachment improved multi-session UX, but in a rare case C-c a z could no longer find the associated AI session. The failure mode was a live attached session being treated as missing when the current working directory no longer matched the session buffer’s directory lookup. Follow-up feedback also exposed a related same-repo case: when a repo already had an active AI session, opening a different file could still force a fresh selection instead of reusing the current session.

• Root cause

  • File-to-session attachment was validated through the current working-dir session scan.
  • If project/root resolution changed between session creation and later lookup, the attached buffer could be dropped even though the session was still alive.
  • For newly opened files without an existing file attachment, the resolver also forced an initial file-session selection even when a remembered repo session already existed.

• Behavior change

  • ai-code-backends-infra--attached-file-session now treats an attached session as valid when:
    • the remembered buffer is still live, and
    • the buffer still parses as a session buffer for the same backend prefix.
  • For newly opened files in the same repo, session resolution now reuses the current remembered repo session by default instead of forcing a new file-session selection.
  • Missing attached sessions still trigger re-selection, and explicit force-prompt rebinding still prompts as before.
  • When multiple active sessions exist for the repo and a newly opened file has no attachment yet, the normal session selector is still used rather than auto-picking arbitrarily.

• Regression coverage

  • Added a focused infra test for the mismatch case: a file-attached session remains reusable even when the current working-dir differs from the session’s original directory.
  • Updated the infra tests to cover the follow-up scenario where a newly opened file in the same repo should reuse the remembered session, while preserving the expected behavior for missing attachments and explicit rebinding.
  • Added focused coverage confirming that a newly opened file still prompts for selection when multiple active sessions exist in the same repo.

• Effect on users

  • C-c a z now continues to reopen the remembered session for a file in cases where the attachment is still correct but directory matching is no longer exact.
  • When there is already an active AI session in a repo, opening a different file in that repo now reuses that remembered session by default instead of unnecessarily prompting for a new association.
  • When there are multiple active AI sessions in the same repo, opening a new file still presents the usual session choice instead of silently binding the file to the wrong session.

;; Before:
;; attached session could be discarded if WORKING-DIR no longer matched
;; ai-code-backends-infra--find-session-buffers.
;; Newly opened files also forced an initial file-session selection.

(valid (and (buffer-live-p attached)
            (memq attached
                  (ai-code-backends-infra--find-session-buffers
                   prefix
                   working-dir))))

;; After:
;; explicit file attachment wins as long as the session buffer is still live
;; and still belongs to the same backend prefix.
;; Newly opened files reuse the remembered repo session unless prompting is
;; explicitly required.

(valid (and (buffer-live-p attached)
            (ai-code-backends-infra--parse-session-buffer-name
             (buffer-name attached)
             prefix)))

• Fixes In rare case, C-c a z cannot find the associated ai coding session buffer #243

📍 Connect Copilot coding agent with Jira, Azure Boards or Linear to delegate work to Copilot in one click without leaving your project management tool.