diff --git a/docs/roadmap/aliases.md b/docs/roadmap/aliases.md
index a55148e..8f6b25b 100644
--- a/docs/roadmap/aliases.md
+++ b/docs/roadmap/aliases.md
@@ -120,6 +120,10 @@ For example, with `list → promptkit list` and
 `list collections → application collections`, the more specific mapping wins
 for `list collections`, while `list prompts` uses the `list` mapping.
 
+Once a matching alias is selected, resolve that route and apply canonical
+validation. A validation failure reports an error; it does not retry a shorter
+alias that could invoke a different command.
+
 Preserve trailing arguments,
 including flags, operands, explicit empty values, and `--`, for canonical
 parsing. Values and operands are not searched for alias text.
@@ -150,8 +154,33 @@ with an existing alias. Reject competing mappings from the same source path to
 different targets; registration order must not select a winner. Identical
 duplicate mappings are accepted under the shared registration conventions.
 
-Detailed prefix interactions remain open below. Aliases do not create canonical
-parent groups, merge integration trees, or replace handlers.
+Aliases do not create canonical parent groups, merge integration trees, or
+replace handlers.
+
+### Prefix interactions and canonical reachability
+
+Alias paths may share prefixes with canonical paths when they introduce a
+distinct route. Preserve existing canonical invocations, including the declared
+operand space of runnable commands.
+
+| Canonical declaration | Proposed alias | Result |
+| --- | --- | --- |
+| `promptkit test all` | `promptkit test full` → `promptkit test all` | Allow the distinct route beneath the shared prefix. |
+| `list projects` | `list collections` → `promptkit list collections` | Allow the distinct route beneath the shared prefix. |
+| `list` group | `list` → `promptkit list` | Reject replacement of the canonical group path. |
+| `run` accepts an operand | `run full` → another command | Reject interception of `full` in the canonical command's operand space. |
+
+Determine command and operand boundaries from declared command structure and
+argument metadata, without executing handlers or application validation.
+Longest-path matching chooses among valid aliases; it does not authorize
+consumption of canonical operands. Sharing a runnable ancestor alone does not
+establish a conflict: check whether the proposed route intercepts that
+ancestor's operands or an existing canonical child route.
+
+Check these conflicts against the complete candidate registry when adding
+either aliases or canonical commands, including later registration. Report the
+conflicting paths and preserve batch atomicity. Chain and group-prefix
+composition are addressed under OD-3.
 
 ### Execution and help
 
@@ -287,14 +316,6 @@ together? How do collections of reusable declarations and group composition
 interact with application-root alias paths? What exact whitespace parsing and
 path validation rules accompany the selected string representation?
 
-### OD-2: Prefix interactions and canonical reachability
-
-How are collisions determined when alias sources or targets overlap canonical
-groups or runnable commands with children? How does longest-token-path matching
-interact with operand boundaries? How are indirect prefix conflicts detected
-when either aliases or canonical commands are added? How are ambiguous paths
-reported?
-
 ### OD-3: Chains and group aliases
 
 How do group aliases compose with more specific aliases and with aliases inside