diff --git a/.changeset/29411-platform-skill-package-contributions.md b/.changeset/29411-platform-skill-package-contributions.md
new file mode 100644
index 00000000000..c6bb512c0b2
--- /dev/null
+++ b/.changeset/29411-platform-skill-package-contributions.md
@@ -0,0 +1,10 @@
+---
+'@objectstack/skills': patch
+---
+
+docs(skills): the platform skill teaches the `contributions` member of the package customizations read
+
+Clause-②: no
+Metadata-protocol: none
+
+`skills/objectstack-platform/SKILL.md` now names `contributions` beside the overrides, extensions and switched-off items that `GET /packages/<id>/customizations` lists: one entry per item another package adds to the base, stamped with its `packageId`; a `field` or `flow` entry names the base's `object` it is on, a `nav` entry names the base's `app`, its `group` when it targets one, and the item id as `name`; `counts.contributions` counts items, not packages. The text is paid for by deleting three restatements in the same file, so the token ceiling is unchanged.
diff --git a/skills/objectstack-platform/SKILL.md b/skills/objectstack-platform/SKILL.md
index f75d219e7d2..9ef3dd3a4e1 100644
--- a/skills/objectstack-platform/SKILL.md
+++ b/skills/objectstack-platform/SKILL.md
@@ -68,10 +68,6 @@ Undeclared keys are handled per surface, in two postures:
   Treat these as errors-in-waiting: a key that only warns today is expected
   to be refused later.
 
-Exact shape: `ObjectStackDefinitionSchema` in
-`node_modules/@objectstack/spec/src/stack.zod.ts`; each collection's item
-schema sits in its domain folder (`data/object.zod.ts`, `ui/view.zod.ts`, …).
-
 → Moved verbatim to [references/bootstrap.md](./references/bootstrap.md) § Map Format (Key → Name) · § Barrel Import Pattern.
 
 ### Strict Validation
@@ -133,6 +129,8 @@ to a new protocol major — never to silence a mismatch.
 
 The pair comes from `POST /api/v1/packages/hotcrm/ensure-customization`: `namespace` = the base's + `_custom`, `dependencies: { hotcrm: '^<major>' }`; `GET /packages/hotcrm/customizations` lists its overrides, extensions and switched-off items, and uninstalling the base is refused (`409`) while the pair exists. Only the pair declares: the save, publish and install doors, `os validate` and `os build` refuse `overrides` from any other package, and a dependent's item under a base item's name — its one fix is a new name. A permission set, position or capability is never overridden: copy it under a new name ("new similar", landing in the pair). An object is extended (`__c` fields, **objectstack-data**); a flow is overridden or copied (**objectstack-automation**).
 
+That read's `contributions` lists what other packages add to the base, one entry per item with its `packageId`: a `field` or `flow` names the base's `object` it is on, a `nav` item the base's `app`, its `group` if any, and its id as `name`; `counts.contributions` counts items, not packages.
+
 ---
 
 ## The App / Platform Boundary
@@ -144,7 +142,7 @@ what the platform owns.
 
 - **Business features belong in the app; capability belongs in the platform.**
   A missing default, a wrong diagnostic, a shape the spec refuses — the fix is
-  upstream. Raise it there; do not compensate for it here.
+  upstream.
 - **Could this be written by something that has only the metadata, and no
   knowledge of this company?** *No* — it encodes this company's own judgement (a
   discount ceiling, who a case is assigned to, how won/lost is booked) ⇒ the
@@ -403,8 +401,7 @@ boot writes `manager_id` itself once every account exists and keeps one set
 by hand, so no seed hook writes it; a display name, an address no entry
 has, the entry itself or a loop is refused at load; `os build` drops the
 key and a non-dev boot creates nothing. `devLogins` creates and grants nothing — it only prints an
-existing account on the boot banner. Pick `demoStaff` whenever the demo
-needs an account to exist.
+existing account on the boot banner.
 
 ---