diff --git a/packages/project/src/objects/pm_project.hook.ts b/packages/project/src/objects/pm_project.hook.ts
index 79d8d24..1ad6b00 100644
--- a/packages/project/src/objects/pm_project.hook.ts
+++ b/packages/project/src/objects/pm_project.hook.ts
@@ -12,11 +12,16 @@ import type { Hook, HookContext } from '@objectstack/spec/data';
  *   and group on a single signal.
  *
  * NOTE — this hook only mutates the incoming `input` payload; it never issues a
- * nested `ctx.api` write. Hook bodies share one QuickJS (asyncify) sandbox that
- * permits a single suspended async call, so a nested engine write crashes the
- * process. That is why `progress_percent` / `actual_cost` (which would need a
- * cross-object rollup from milestones / timesheets) are stored fields kept in
- * sync by seed/client, not by this hook.
+ * nested `ctx.api` write. Nested cross-object writes from a hook are safe now
+ * (framework#1867 is fixed), but `progress_percent` / `actual_cost` are still
+ * deliberately NOT hook roll-ups — neither is a plain aggregate of a child field:
+ *   - `actual_cost` is an externally-computed actual (hours × a person/role rate).
+ *     `pm_timesheet` records hours only; there is no child cost column to sum, and
+ *     the per-rate data lives outside the 4-object CHARTER schema.
+ *   - `progress_percent` is a curated delivery metric, not a naive completed/total
+ *     milestone count (the seeded per-project values differ where a count would
+ *     flatten them to the same number).
+ * Both are kept by seed/client; see each field's note in pm_project.object.ts.
  *
  * IMPORTANT — the handler runs **body-only** in the QuickJS sandbox: only the
  * function body ships, so module-scope helpers are NOT in scope at runtime.
diff --git a/packages/project/src/objects/pm_project.object.ts b/packages/project/src/objects/pm_project.object.ts
index bc1cdae..2dac9a7 100644
--- a/packages/project/src/objects/pm_project.object.ts
+++ b/packages/project/src/objects/pm_project.object.ts
@@ -181,8 +181,11 @@ export const Project = ObjectSchema.create({
       required: false,
       group: 'budget',
       description:
-        'Cost to date. Maintained by seed/client or an out-of-sandbox worker — NOT a live ' +
-        'hook rollup (a nested write from a timesheet hook crashes the QuickJS sandbox).',
+        'Cost to date — an externally-computed actual (hours × a person/role rate). ' +
+        'pm_timesheet records hours only, so there is no child cost column to sum: this is ' +
+        'not a summary/hook roll-up but a value set by seed/client or a finance worker. ' +
+        '(Nested hook writes are safe now — framework#1867 — the blocker is the missing rate, ' +
+        'not the sandbox.)',
     }),
 
     // Team
@@ -206,8 +209,10 @@ export const Project = ObjectSchema.create({
       min: 0,
       max: 100,
       description:
-        'Share of completed milestones. Maintained by seed/client (not a live hook ' +
-        'rollup — see actual_cost note).',
+        'Delivery progress (0–100). A curated metric, not a naive completed/total milestone ' +
+        'count — the seeded per-project values differ where a count would flatten them — so it ' +
+        'is kept by seed/client. It could be made a live milestone roll-up via an afterInsert/' +
+        'afterUpdate hook now that framework#1867 is fixed, if count-based progress is acceptable.',
     }),
   },
 
diff --git a/packages/project/src/views/pm_timesheet.view.ts b/packages/project/src/views/pm_timesheet.view.ts
index c70bf8f..6a5d4d4 100644
--- a/packages/project/src/views/pm_timesheet.view.ts
+++ b/packages/project/src/views/pm_timesheet.view.ts
@@ -4,7 +4,8 @@ import { defineView } from '@objectstack/spec/ui';
 
 /**
  * Timesheet views — daily effort entries, grouped by project, with a billable
- * tab. Timesheets feed the project's actual_cost (maintained out of sandbox).
+ * tab. Timesheets record effort (hours); the project's actual_cost is computed
+ * externally (hours × rate), not rolled up from these rows.
  */
 export const TimesheetViews = defineView({
   list: {