fix(terminal): treat 0.12.2 prerelease nightlies as affected (#161)

Claude review: is_affected_version() ignored vim.version().prerelease, so a
"0.12.2-dev" nightly built before the #39152 backport landed reports version
0.12.2 and was treated as fixed (shim off) despite still having the bug. Treat a
0.12.2 prerelease as affected; the 0.12.2 release (prerelease == nil) and 0.13+
remain unaffected. Enabling the shim on a build that already has the fix is a
verified no-op, so erring toward "affected" at the boundary is safe. Adds unit
tests for the prerelease boundary.

Change-Id: Iaa21f112cb21a16120fef269eec6361e0639796d
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Signed-off-by: Thomas Kosiewski <tk@coder.com>

Author: ThomasK33

lua/claudecode/terminal/paste_fix.lua

@@ -27,7 +27,17 @@ function M.is_affected_version()
   end
   local minor = v.minor or 0
   local patch = v.patch or 0
-  return minor < 12 or (minor == 12 and patch < 2)
+  if minor < 12 or (minor == 12 and patch < 2) then
+    return true
+  end
+  -- The fix shipped in the 0.12.2 *release*. A 0.12.2 prerelease/nightly
+  -- (vim.version().prerelease is set, e.g. "dev") can predate the backport, so
+  -- treat it as affected. Enabling the shim on a build that already has the fix
+  -- is a verified no-op, so erring toward "affected" at the boundary is safe.
+  if minor == 12 and patch == 2 and v.prerelease then
+    return true
+  end
+  return false
 end
 
 --- Resolve whether the shim should be active for a given config value.

tests/unit/terminal/paste_fix_spec.lua

@@ -123,6 +123,27 @@ describe("claudecode.terminal.paste_fix", function()
         assert.are.equal(expected, paste_fix.is_affected_version())
       end)
     end
+
+    it("treats a 0.12.2 prerelease (nightly built before the backport) as affected", function()
+      vim.version = function()
+        return { major = 0, minor = 12, patch = 2, prerelease = "dev" }
+      end
+      assert.is_true(paste_fix.is_affected_version())
+    end)
+
+    it("treats the 0.12.2 release (no prerelease) as fixed", function()
+      vim.version = function()
+        return { major = 0, minor = 12, patch = 2, prerelease = nil }
+      end
+      assert.is_false(paste_fix.is_affected_version())
+    end)
+
+    it("treats a 0.13.0 prerelease as fixed (past the boundary)", function()
+      vim.version = function()
+        return { major = 0, minor = 13, patch = 0, prerelease = "dev" }
+      end
+      assert.is_false(paste_fix.is_affected_version())
+    end)
   end)
 
   describe("install (cooperative override)", function()