OpenRouter model definition helpers

[mgalgs]

I use OpenRouter for most of my gptel usage but have been missing the pricing and other info from the built-in gptel--openai-models models plist, but I didn't want to maintain a hard-coded version for my OpenRouter models.

OpenRouter actually has an API that supplies this information, so I vibe-coded up a helper function to augment my OpenRouter models list with this information automatically:

My models list is still just a bare list of models, no need to manually maintain model metadata:

(setq gptel-model 'openai/gpt-5-chat
        gptel-backend (gptel-make-openai "OpenRouter"
                        :host "openrouter.ai"
                        :endpoint "/api/v1/chat/completions"
                        :stream t
                        :key (get-openrouter-api-key)
                        :models (m/augment-openrouter-models-list
                                 '(anthropic/claude-3.7-sonnet
                                   anthropic/claude-3.7-sonnet:thinking
                                   anthropic/claude-opus-4
                                   anthropic/claude-sonnet-4
                                   deepseek/deepseek-chat-v3-0324
                                   deepseek/deepseek-r1-0528
                                   google/gemini-2.5-flash
                                   google/gemini-2.5-pro
                                   moonshotai/kimi-k2
                                   openai/gpt-4o-2024-11-20
                                   openai/gpt-5
                                   openai/gpt-5-chat
                                   openai/gpt-oss-120b
                                   qwen/qwen3-235b-a22b-2507
                                   qwen/qwen3-235b-a22b-thinking-2507
                                   qwen/qwen3-coder
                                   qwen/qwen3-max
                                   x-ai/grok-3-mini-beta
                                   z-ai/glm-4.5
                                   z-ai/glm-4.5-air
                                   x-ai/grok-code-fast-1))))

Only lightly tested but seems to be working well so far!

Without further ado, here's the code:

(defun m--fetch-openrouter-models ()
  "Fetch and parse the OpenRouter models API synchronously.
Return an alist of (ID-STRING . raw-model-plist) entries."
  (let ((url-request-extra-headers '(("Accept" . "application/json"))))
    (with-current-buffer
        (url-retrieve-synchronously "https://openrouter.ai/api/v1/models" t t 15)
      (goto-char (point-min))
      (re-search-forward "\n\n") ;; skip HTTP headers
      (let* ((raw (buffer-substring-no-properties (point) (point-max)))
             (data (json-parse-string raw
                                      :object-type 'plist
                                      :array-type 'list
                                      :null-object nil
                                      :false-object :json-false)))
        (mapcar (lambda (m) (cons (plist-get m :id) m))
                (plist-get data :data))))))

(defun m--guess-capabilities (desc)
  "Heuristically guess capabilities from DESC string."
  (let ((d (downcase (or desc "")))
        caps)
    (when (string-match-p "tool" d)    (push 'tool-use caps))
    (when (string-match-p "reason" d)  (push 'reasoning caps))
    (when (string-match-p "image" d)   (push 'media caps))
    (when (string-match-p "json" d)    (push 'json caps))
    (when (string-match-p "url" d)     (push 'url caps))
    (nreverse caps)))

(defun m--convert-openrouter-to-gptel (m)
  "Convert OpenRouter model plist M into gptel--openai-models-style plist."
  (let* ((desc (plist-get m :description))
         (ctx (or (plist-get m :context_length)
                  (plist-get (plist-get m :top_provider) :context_length)))
         (pricing (plist-get m :pricing))
         (in (and pricing
                  (* 1e6 (string-to-number (or (plist-get pricing :prompt) "0")))))
         (out (and pricing
                   (* 1e6 (string-to-number (or (plist-get pricing :completion) "0"))))))
    (append (list :description desc)
            (when ctx (list :context-window (/ ctx 1000.0)))
            (when in (list :input-cost in))
            (when out (list :output-cost out))
            (let ((caps (m--guess-capabilities desc)))
              (when caps (list :capabilities caps))))))

(defun m/augment-openrouter-models-list (ids)
  "Augment model IDS using the OpenRouter API.
Returns a list of (symbol . plist).  If a model is missing, returns (id)."
  (let* ((all (m--fetch-openrouter-models))
         (tbl (make-hash-table :test 'equal)))
    (dolist (m all)
      (puthash (car m) (cdr m) tbl))
    (mapcar
     (lambda (id)
       (let* ((id-str (if (symbolp id) (symbol-name id) id))
              (m (gethash id-str tbl)))
         (if m
             (cons (intern id-str) (m--convert-openrouter-to-gptel m))
           (list (intern id-str)))))
     ids)))