Record flag alias scope and target availability decisions

docs/roadmap/aliases.md

@@ -272,9 +272,28 @@ declaring a command alias, using the shared registration conventions above.
 Support application-wide mappings and mappings scoped to a canonical command.
 The selected canonical command determines the applicable flag aliases, so a
 command-scoped mapping works through every command alias that reaches that
-target. An application-wide help alias provides the same convenience throughout
-the application. Scope precedence and handling of targets unavailable on some
-commands remain open.
+target. A command-scoped mapping takes precedence over an application-wide
+mapping for the same alias spelling. Reject different-target mappings within
+the same scope; identical duplicates are harmless. Registration order does not
+choose a winner, and neither scope may overload an applicable canonical flag.
+
+An application-wide mapping is available wherever its target flag exists and
+contributes nothing elsewhere. For example, `--colour → --color` need not require
+every command to define `--color`. On a command without that target, `--colour`
+receives the ordinary unknown-flag error. Reusable application-wide declarations
+are valid even when no currently installed command has their target flag.
+
+A command-scoped mapping requires its named canonical command and target flag
+to exist in the complete candidate installation batch. An unavailable explicit
+destination is invalid configuration.
+
+Application-wide mappings also apply to built-in flags at the application root
+and on groups. In particular, `--hlep → --help` works wherever canonical
+`--help` works, including help for alias-only prefixes.
+
+Later registration repeats validation against the candidate registry. Newly
+installed commands gain applicable application-wide aliases automatically;
+canonical spelling collisions reject the batch under the collision rules below.
 
 ### Token interpretation
 
@@ -297,7 +316,7 @@ arity, boolean syntax, or option termination.
 
 Match the complete flag name. Length precedence does not apply: `--out` and
 `--output` are different names, and only `--out` participates in alias lookup in
-`--out=value`. Scope precedence remains a separate decision. Resolution must
+`--out=value`. Use the scope precedence selected above. Resolution must
 be deterministic and must not depend on registration order.
 
 ### Canonical flag collisions
@@ -326,8 +345,8 @@ spelling accumulate in order. Alias resolution adds no second conversion or
 input-preparation lifecycle.
 
 Flag aliases do not change canonical flag ownership or add new provider
-capabilities. Short-flag support, chains, alias-to-alias scope conflicts,
-target validation, and help presentation remain open below.
+capabilities. Short-flag support, chains and their validation, and help
+presentation remain open below.
 
 ## Work needed from the baseline
 
@@ -378,10 +397,8 @@ canonical invocation paths?
 
 ### OD-6: Flag alias scope and composition
 
-How do application-wide and command-scoped mappings interact when both apply?
-How is an application-wide mapping treated on commands lacking its target flag?
-How are aliases applied to built-in help on groups and at the application root?
-Which short-flag forms are supported? Are flag-alias chains supported, and how
-are alias-to-alias conflicts, cycles, and missing targets validated at installation
-and later registration? How are flag aliases exposed in help and diagnostic
-spelling?
+Scope precedence, target availability, and application to built-in help are
+selected above. Which short-flag forms are supported? Are flag-alias chains
+supported, and how do scope precedence and target availability apply through
+a chain? How are cycles validated at installation and later registration?
+How are flag aliases exposed in help and diagnostic spelling?