diff --git a/docs/architecture.md b/docs/architecture.md
index 9c108b30..2709a62d 100644
--- a/docs/architecture.md
+++ b/docs/architecture.md
@@ -103,6 +103,12 @@ A coworker is a durable Bot profile:
 
 A channel is a conversation with one coworker and a CopilotKit Intelligence thread mapping. Starting a new channel creates a new thread.
 
+Who may reach one is decided by membership: every channel route resolves the caller in
+`channel_memberships` and refuses without a row. `channels.allowed_groups` is declared in the
+tenant package and stored, and is not part of that decision — `users.groups` is never populated by
+any sign-in path, so a group-based rule has nothing to evaluate. Treat it as a declaration waiting
+on group membership from the identity provider, not as a control that is running.
+
 See [coworkers.md](coworkers.md).
 
 ## Components
diff --git a/docs/configuration.md b/docs/configuration.md
index 4836f0d4..75b56e16 100644
--- a/docs/configuration.md
+++ b/docs/configuration.md
@@ -306,6 +306,18 @@ channels:
 
 Each channel requires `id`, `name`, `description`, `permitted_agents`, and `allowed_groups`. Every `permitted_agents` entry must match an agent id.
 
+`allowed_groups` is validated and stored, and nothing reads it. It decides nothing today, and a
+deployment that writes one must not treat it as an access control. Both halves of that control are
+missing, not one: `users.groups` exists as a column and no sign-in path, claim mapping or admin
+screen ever populates it, so there is nothing for a channel's list to be compared against. Channel
+access is decided by membership alone — every channel route resolves the caller's row in
+`channel_memberships` and refuses without it.
+
+Package-declared channels get no membership rows from `synchronizeTenantPackage`, so today they
+are unreachable rather than open. The field is kept because the enforcement it is named for needs
+the declaration and needs group membership arriving from the identity provider, and neither this
+column nor `users.groups` is the wrong shape for it.
+
 ### `model.yaml`
 
 ```yaml
diff --git a/server/src/db/schema/core.ts b/server/src/db/schema/core.ts
index 4dace4b9..87fe6a86 100644
--- a/server/src/db/schema/core.ts
+++ b/server/src/db/schema/core.ts
@@ -50,6 +50,14 @@ export const users = pgTable("users", {
   name: text("name"),
   image: text("image"),
   emailVerified: boolean("email_verified").notNull().default(false),
+  /**
+   * The person's groups, for a group-based rule to be evaluated against.
+   *
+   * Empty on every row: no sign-in path, claim mapping or admin screen writes this, and nothing
+   * reads it. It is the other half of `channels.allowedGroups`, and #82 is about the pair. Anything
+   * that starts deciding access on a group has to populate this first, or it decides on an empty
+   * list for everybody.
+   */
   groups: text("groups").array().notNull().default([]),
   createdAt: createdAt(),
   updatedAt: updatedAt(),
@@ -221,6 +229,16 @@ export const channels = pgTable(
     name: text("name").notNull(),
     description: text("description").notNull(),
     suggestedPrompts: text("suggested_prompts").array().notNull().default([]),
+    /**
+     * Which groups the tenant package says this channel is for.
+     *
+     * Written by `synchronizeTenantPackage` and read by nothing. Channel access is membership: every
+     * route resolves the caller in `channelMemberships` and refuses without a row, and this column is
+     * not consulted on the way. It is not currently a hole, because package channels get no
+     * membership rows either and so are unreachable rather than open, but it is a control the name
+     * promises and nothing keeps. See #82, and `users.groups`, which is the half that has to arrive
+     * from the identity provider before this one can decide anything.
+     */
     allowedGroups: text("allowed_groups").array().notNull().default([]),
     packageId: uuid("package_id").references(() => deploymentPackages.id, {
       onDelete: "set null",