feat(save): add an atomic conflict gate for enum and relation fields

The text conflict gate (pearl--resolve-conflict) is built for mergeable text — it can open an smerge buffer, stash to the kill ring, and advance a SHA hash. None of that fits a state, priority, assignee, or label conflict, where the value is a single id or scalar that can't be combined.

pearl--resolve-atomic-conflict is the sibling for those fields: it prompts use-local / use-remote / cancel (no merge option), and delegates the actual push and the baseline advance to the caller's two callbacks, so it stays free of any field-specific mechanics. It maps to the same outcome contract as the text gate — cancel to conflict/cancelled, use-local to pushed or failed/push-failed, use-remote to resolved-remote.

It's not wired into a saver yet — the per-field savers in the next commit call it.

1 files changed, 56 insertions, 0 deletions

diff --git a/tests/test-pearl-conflict.el b/tests/test-pearl-conflict.el
index 138e622..56d3c84 100644
--- a/tests/test-pearl-conflict.el
+++ b/tests/test-pearl-conflict.el
@@ -224,6 +224,62 @@
           (should (string= (secure-hash 'sha256 "merged text")
                            (org-entry-get marker "LINEAR-DESC-SHA256"))))))))
 
+;;; --resolve-atomic-conflict (enum/relation fields, no merge)
+
+(ert-deftest test-pearl-resolve-atomic-conflict-cancel ()
+  "Cancel pushes nothing, takes nothing, and reports conflict/cancelled."
+  (let (pushed took outcome)
+    (cl-letf (((symbol-function 'pearl--read-atomic-conflict-resolution)
+               (lambda (_) 'cancel)))
+      (pearl--resolve-atomic-conflict
+       "ENG-1 state" "In Progress" "Done"
+       (lambda (cb) (setq pushed t) (funcall cb t))
+       (lambda () (setq took t))
+       (lambda (status reason) (setq outcome (list status reason))))
+      (should-not pushed)
+      (should-not took)
+      (should (equal '(conflict cancelled) outcome)))))
+
+(ert-deftest test-pearl-resolve-atomic-conflict-use-local-pushes ()
+  "Use-local runs the push; on success reports pushed."
+  (let (pushed took outcome)
+    (cl-letf (((symbol-function 'pearl--read-atomic-conflict-resolution)
+               (lambda (_) 'use-local)))
+      (pearl--resolve-atomic-conflict
+       "ENG-1 state" "In Progress" "Done"
+       (lambda (cb) (setq pushed t) (funcall cb t))
+       (lambda () (setq took t))
+       (lambda (status reason) (setq outcome (list status reason))))
+      (should pushed)
+      (should-not took)
+      (should (equal '(pushed nil) outcome)))))
+
+(ert-deftest test-pearl-resolve-atomic-conflict-use-local-push-failure ()
+  "A failed local push reports failed/push-failed."
+  (let (outcome)
+    (cl-letf (((symbol-function 'pearl--read-atomic-conflict-resolution)
+               (lambda (_) 'use-local)))
+      (pearl--resolve-atomic-conflict
+       "ENG-1 state" "In Progress" "Done"
+       (lambda (cb) (funcall cb nil))
+       (lambda () nil)
+       (lambda (status reason) (setq outcome (list status reason))))
+      (should (equal '(failed push-failed) outcome)))))
+
+(ert-deftest test-pearl-resolve-atomic-conflict-use-remote-takes-no-push ()
+  "Use-remote adopts Linear's value, never pushes, and reports resolved-remote."
+  (let (pushed took outcome)
+    (cl-letf (((symbol-function 'pearl--read-atomic-conflict-resolution)
+               (lambda (_) 'use-remote)))
+      (pearl--resolve-atomic-conflict
+       "ENG-1 state" "In Progress" "Done"
+       (lambda (cb) (setq pushed t) (funcall cb t))
+       (lambda () (setq took t))
+       (lambda (status reason) (setq outcome (list status reason))))
+      (should took)
+      (should-not pushed)
+      (should (equal '(resolved-remote nil) outcome)))))
+
 ;;; --conflict-has-markers-p
 
 (ert-deftest test-pearl-conflict-has-markers-p ()