Include overlay author controls in the sequence proposal

docs/roadmap/sequences.md

@@ -118,6 +118,31 @@ The lower record's `temperature` is discarded. Subsequent defaulting or other
 lifecycle operations retain their separately defined semantics. Recursive
 field-by-field overlay of matching records is outside this selected operation.
 
+### Selected Overlay Control
+
+Selected overlay authors must be able to choose any of the three operations
+for a sequence supplied by the overlay, including records authored inline.
+The operation applies against the existing effective sequence at that path.
+For an existing sequence `[foo, bar]`:
+
+| Overlay contribution | Selected operation | Result |
+| --- | --- | --- |
+| `[foo*]` | Replacement by identity | `[foo*, bar]` |
+| `[baz]` | Append | `[foo, bar, baz]` |
+| `[bar, baz]` | Whole-sequence replacement | `[bar, baz]` |
+
+Here `foo*` has the same identity as `foo` and supplies its complete replacement
+record. Append retains its duplicate-identity error semantics. The retained
+records and replacement behavior are settled; ordering shown follows the
+recommendation under OD-4.
+
+An import-only declaration mechanism cannot cover inline overlay sequences.
+OD-2 must provide an overlay-authorable declaration site, and OD-5 must select
+operation names and omission behavior. The current
+[selected-overlay contract](../config.md#selected-overlays) prohibits `configkit`
+in overlays. Any new control syntax must explicitly account for that boundary;
+supporting sequence controls does not itself require enabling overlay imports.
+
 ### Optional Application-Owned Identity Constraints
 
 Retain an interface through which applications may register a collection and
@@ -234,24 +259,27 @@ produce a final collection that no longer satisfies that identity declaration.
 
 ### OD-2. Where Does Configuration Declare Collection Policy?
 
-Is `key` on a `sequence-item` import sufficient, or should configuration have a
-collection declaration that also covers inline sequences, ordinary mapping
-imports containing sequences, and selected overlays? How does such a declaration
-address a collection inside an imported item?
+Where should configuration declare collection identity and combination choices
+for imported items, inline sequences, and sequences supplied by ordinary mapping
+imports? Selected overlays must support author selection of all three operations
+for inline sequences. How does a declaration address a collection inside an
+imported item?
 
 **Initial recommendation:** Define one destination-scoped collection policy
-model first. Evaluate a configuration-level declaration alongside import syntax
-against these workflows before selecting the surface. Collection identity must
-apply consistently to all participating records at that destination, including
-inline records. Resolve relative destinations and item-local scopes using their
-existing ownership boundaries.
+model first. Prefer a configuration-level collection declaration usable in base
+sources and selected overlays, with import annotations considered as shorthand.
+This gives inline and imported records a common policy surface. Collection
+identity must apply consistently to all participating records at that
+destination. Resolve relative destinations and item-local scopes using their
+existing ownership boundaries. Define the sequence controls accepted in overlays
+explicitly, including their relationship to the current `configkit` prohibition.
 
-**Alternative:** Limit this feature to policies declared on item imports. This
-keeps the initial syntax small and directly serves imported prompt collections,
-but leaves inline-only collections and overlay-authored append without a natural
-declaration site. A separate collection declaration covers those cases at the
-cost of more configuration structure; an import shorthand would require a clear
-relationship to that declaration.
+**Alternative:** Put controls beside each sequence through a local wrapper or
+directive form. This keeps the operation close to the affected value and supports
+inline overlay records, but requires distinguishing control syntax from
+application data and defining how imported contributions share that policy.
+A configuration-level declaration adds path references and configuration
+structure; import shorthand also needs a clear relationship to that declaration.
 
 ### OD-3. What Constitutes Identity, And When Can It Change?
 
@@ -274,12 +302,13 @@ support more schemas but add type-equality and addressing rules. A load-wide fix
 identity definition simplifies agreement across tiers; allowing a replacement to
 establish a new definition gives independently authored layers more flexibility.
 
-### OD-4. What Does An Import's Combination Choice Control?
+### OD-4. What Does A Combination Choice Control?
 
-What happens when peer imports into the same destination request different
-operations, or when some contributions omit the operation? Settle ordering for
-replacement by identity, including where replaced records and new identities
-appear.
+What happens when peer imports or collection declarations at the same destination
+request different operations, or when some contributions omit the operation?
+Settle ordering for replacement by identity, including where replaced records
+and new identities appear. Apply the same operation semantics to selected
+overlay contributions.
 
 **Initial recommendation:** Assemble one strict sequence per destination in
 each tier, then apply its agreed operation at the precedence boundary. Reject
@@ -351,10 +380,10 @@ version headers?
 precedence assembly. Validate records at the relevant collection assembly
 boundaries and uniqueness across each combined result. Preserve existing
 typed-default and application-resolution semantics unless their inclusion is
-explicitly chosen. Decide selected-overlay coverage with OD-2; it is part of
-source precedence but currently has no import declaration site. Account for
-item-local helpers and source-version consumption before deciding identity is
-available, consistent with the current lifecycle.
+explicitly chosen. Selected-overlay combination is included in the settled scope;
+its declaration mechanism remains under OD-2. Account for item-local helpers and
+source-version consumption before deciding identity is available, consistent
+with the current lifecycle.
 
 The settled OD-1 guarantee covers final validation of application constraints.
 Validating the final collection does not itself change how defaults, inheritance,