diff --git a/repositories.tf b/repositories.tf
index f46d493..7b63450 100644
--- a/repositories.tf
+++ b/repositories.tf
@@ -252,6 +252,176 @@ module "repo_osac" {
   }
 }
 
+# Branch protection for any release-X.Y stabilization branch (e.g.
+# release-0.4, cut per docs/RELEASING.md in osac-project/osac), mirroring
+# repo_osac's own ci-status-checks ruleset above: same three required
+# checks, same review requirements (real approving-review-count embedded
+# directly in the ruleset's own pull_request rule, not left to classic
+# branch protection -- github_branch_protection can't target a branch
+# that doesn't exist yet, so there's no equivalent of main's "real review
+# enforcement happens at the classic-protection level" split here), same
+# bypass actors as repo_osac's own ruleset_bypass_team_ids (managers,
+# ci-duty) plus the GitHub Merge Queue app (262318) -- that one specific
+# bypass actor matches the module's own dynamic bypass_actors block
+# (modules/common_repository/main.tf): it exists so the queue bot can
+# push a rebased commit past deletion/non_fast_forward after queue checks
+# pass, needed here because non_fast_forward (unlike repo_osac's
+# merge_queue-bundled ruleset, which has no such rule to bypass at all)
+# is part of this ruleset. Also blocks deletion/force-push, since a
+# release branch has none of main's own reasons to allow force-push.
+#
+# NOT generated by the shared module: release-* is an osac-specific
+# pattern, not something every repo this module manages needs, so this
+# is a standalone resource rather than a new module variable (unlike
+# tag_rulesets above, which genuinely is generic across repos).
+#
+# Created out-of-band via the GitHub API on 2026-11-04 when release-0.4
+# was actually cut (before this repo's own plan/apply cycle could run);
+# codified here afterward so it's reviewable and reproducible like
+# everything else in this file, via the `import` block below.
+resource "github_repository_ruleset" "release_branch_protection" {
+  name        = "release-branch-protection"
+  repository  = "osac"
+  target      = "branch"
+  enforcement = "active"
+
+  bypass_actors {
+    actor_id    = 1
+    actor_type  = "OrganizationAdmin"
+    bypass_mode = "always"
+  }
+  bypass_actors {
+    actor_id    = 262318
+    actor_type  = "Integration"
+    bypass_mode = "always"
+  }
+  bypass_actors {
+    actor_id    = github_team.all["managers"].id
+    actor_type  = "Team"
+    bypass_mode = "always"
+  }
+  bypass_actors {
+    actor_id    = github_team.all["ci-duty"].id
+    actor_type  = "Team"
+    bypass_mode = "always"
+  }
+
+  conditions {
+    ref_name {
+      include = ["refs/heads/release-*"]
+      exclude = []
+    }
+  }
+
+  rules {
+    required_status_checks {
+      # Matches repo_osac's own merge_queue-enabled branches: the queue
+      # already re-tests against latest before merging, so requiring
+      # checks to be re-run up to date here would be redundant.
+      strict_required_status_checks_policy = false
+
+      required_check {
+        context        = "CI"
+        integration_id = 15368
+      }
+      required_check {
+        context        = "jira-reference"
+        integration_id = 15368
+      }
+      required_check {
+        context        = "E2E"
+        integration_id = 4966101
+      }
+    }
+
+    pull_request {
+      required_approving_review_count   = 1
+      dismiss_stale_reviews_on_push     = true
+      require_code_owner_review         = true
+      require_last_push_approval        = false
+      required_review_thread_resolution = false
+      allowed_merge_methods             = ["merge", "squash", "rebase"]
+    }
+
+    deletion         = true
+    non_fast_forward = true
+  }
+
+  depends_on = [module.repo_osac]
+}
+
+import {
+  to = github_repository_ruleset.release_branch_protection
+  id = "osac:26559405"
+}
+
+# Merge queue for release-0.4 specifically. GitHub rejects a wildcard
+# ref_name pattern when a merge_queue rule is present ("Wildcard ref
+# names are not supported when merge queue is enabled" -- confirmed
+# live), so this can't be folded into release_branch_protection above.
+# A sibling resource like this one is needed per release branch going
+# forward (0.5, 0.6, ...), unlike that wildcard ruleset which only had
+# to be created once.
+#
+# Matches the live ruleset's actual bypass_actors exactly (it has no
+# restrictive rule for them to bypass -- merge_queue alone doesn't
+# restrict direct pushes, that's release_branch_protection's job -- but
+# they were set on creation and this codifies what's live rather than
+# narrowing it as a drive-by cleanup under this change's scope).
+resource "github_repository_ruleset" "release_0_4_merge_queue" {
+  name        = "release-0.4-merge-queue"
+  repository  = "osac"
+  target      = "branch"
+  enforcement = "active"
+
+  bypass_actors {
+    actor_id    = 1
+    actor_type  = "OrganizationAdmin"
+    bypass_mode = "always"
+  }
+  bypass_actors {
+    actor_id    = 262318
+    actor_type  = "Integration"
+    bypass_mode = "always"
+  }
+  bypass_actors {
+    actor_id    = github_team.all["managers"].id
+    actor_type  = "Team"
+    bypass_mode = "always"
+  }
+  bypass_actors {
+    actor_id    = github_team.all["ci-duty"].id
+    actor_type  = "Team"
+    bypass_mode = "always"
+  }
+
+  conditions {
+    ref_name {
+      include = ["refs/heads/release-0.4"]
+      exclude = []
+    }
+  }
+
+  rules {
+    merge_queue {
+      merge_method                      = "SQUASH"
+      max_entries_to_build              = 4
+      max_entries_to_merge              = 5
+      min_entries_to_merge              = 1
+      min_entries_to_merge_wait_minutes = 5
+      check_response_timeout_minutes    = 180
+      grouping_strategy                 = "ALLGREEN"
+    }
+  }
+
+  depends_on = [module.repo_osac]
+}
+
+import {
+  to = github_repository_ruleset.release_0_4_merge_queue
+  id = "osac:26569686"
+}
+
 module "repo_cloudkit_operator" {
   source      = "./modules/common_repository"
   visibility  = "public"