Fix review findings: missing ::model spec, attachment->wire, docs

- Add (s/def ::model string?) for tool.execution_complete-data
- Add :github-reference case to attachment->wire with correct wire format
- Add ::attachment-state spec and collision comment for clarity
- Add :github-reference row to API.md attachment types table

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: krukow

doc/reference/API.md

@@ -594,6 +594,7 @@ Send a message to the session. Returns immediately with the message ID.
 | `:file` | `:type`, `:path` | `:display-name`, `:line-range` | File attachment |
 | `:directory` | `:type`, `:path` | `:display-name`, `:line-range` | Directory attachment |
 | `:selection` | `:type`, `:file-path`, `:display-name` | `:selection-range`, `:text` | Code selection attachment |
+| `:github-reference` | `:type`, `:number`, `:title`, `:reference-type`, `:state`, `:url` | — | GitHub issue, PR, or discussion reference |
 
 `:line-range` is a map with `:start` and `:end` line numbers (zero-based) to restrict the attachment to a range of lines:
 

src/github/copilot_sdk/specs.clj

@@ -275,9 +275,12 @@
          #(= :selection (:type %))))
 
 ;; GitHub reference attachment (issue, PR, or discussion)
+;; Note: ::state is already defined as (instance? Atom) for the client record,
+;; so we cannot use s/keys here — manual predicates validate the :state field instead.
 (s/def ::number nat-int?)
 (s/def ::reference-type #{"issue" "pr" "discussion"})
 (s/def ::url string?)
+(s/def ::attachment-state string?)
 (s/def ::github-reference-attachment
   (s/and map?
          #(= :github-reference (:type %))
@@ -665,4 +668,5 @@
 ;; Session model operations (session.model.getCurrent / switchTo)
 ;; -----------------------------------------------------------------------------
 
+(s/def ::model string?)
 (s/def ::model-id (s/nilable string?))

src/github/copilot_sdk/util.clj

@@ -97,6 +97,14 @@
       (:selection-range att) (assoc :selection (clj->wire (:selection-range att)))
       (:text att) (assoc :text (:text att)))
 
+    :github-reference
+    {:type "github_reference"
+     :number (:number att)
+     :title (:title att)
+     :referenceType (name (:reference-type att))
+     :state (:state att)
+     :url (:url att)}
+
     ;; :file and :directory
     (cond-> {:type (name (:type att))
              :path (:path att)}