How to edit Session Token's file name?

Photoshop UXP Plugin API
14

Here you go, a rough demo of what you want.
It bypasses user input and gets an entry for the opened file’s parent folder using getEntryWithUrl() and then generates a session token for each jpeg as it saves them.

const { app, core } = require("photoshop");
const batchPlay = require("photoshop").action.batchPlay;
const lfs = require("uxp").storage.localFileSystem;

try {
  // Helper functions
  const getParentFolderEntry = async (filepath) => {
    const folderPath = path.dirname(filepath);
    return await lfs.getEntryWithUrl(folderPath);
  };

  const getAnimationFrameCount = async () => {
    return await batchPlay(
      [
        {
          _obj: "get",
          _target: [
            {
              _property: "frameCount",
            },
            {
              _ref: "animationClass",
              _enum: "ordinal",
              _value: "targetEnum",
            },
          ],
          _options: {
            dialogOptions: "dontDisplay",
          },
        },
      ],
      {}
    );
  };

 const selectAnimationFrame = async (index) => {
    return await batchPlay(
      [
        {
          _obj: "select",
          _target: [
            {
              _ref: "animationFrameClass",
              _index: index,
            },
          ],
          _options: {
            dialogOptions: "dontDisplay",
          },
        },
      ],
      {}
    );
  };

  const makeSnapshot = async (name) => {
    return batchPlay(
      [
        {
          _obj: "make",
          _target: [
            {
              _ref: "snapshotClass",
            },
          ],
          from: {
            _ref: "historyState",
            _property: "currentHistoryState",
          },
          name: name,
          using: {
            _enum: "historyState",
            _value: "fullDocument",
          },
          _isCommand: true,
          _options: {},
        },
      ],
      {}
    );
  };

  const revertToSnapshot = async (name) => {
    return batchPlay(
      [
        {
          _obj: "select",
          _target: [
            {
              _ref: "snapshotClass",
              _name: name,
            },
          ],
          _isCommand: true,
          _options: {
            dialogOptions: "dontDisplay",
          },
        },
      ],
      {}
    );
  };

  const deleteSnapshot = async (name) => {
    return batchPlay(
      [
        {
          _obj: "delete",
          _target: [
            {
              _ref: "historyState",
              _name: name,
            },
          ],
          _isCommand: true,
          _options: {
            dialogOptions: "dontDisplay",
          },
        },
      ],
      {}
    );
  };

  const saveJPEG = async (saveFolder, newFilename, quality) => {
    try {
      const doc = app.activeDocument;
      const theNewFile = await saveFolder.createFile(newFilename, {
        overwrite: true,
      });
      const saveFile = await lfs.createSessionToken(theNewFile);
       return batchPlay(
        [
          {
            _obj: "save",
            as: {
              _obj: "JPEG",
              extendedQuality: quality,
              matteColor: {
                _enum: "matteColor",
                _value: "none",
              },
            },
            in: {
              _path: saveFile,
              _kind: "local",
            },
            documentID: doc.id,
            lowerCase: true,
            saveStage: {
              _enum: "saveStageType",
              _value: "saveBegin",
            },
            _isCommand: true,
            _options: {
              dialogOptions: "dontDisplay",
            },
          },
        ],
        {}
      );
    } catch (error) {
      console.log(error);
    }
  };

  // Main process
  await core.executeAsModal(async () => {
    const file = await lfs.getFileForOpening();
    const saveFolder = await getParentFolderEntry(file.nativePath);
     await app.open(file);
     const doc = app.activeDocument;
     const baseFilename = doc.name.slice(0, doc.name.lastIndexOf("."));

     const countFrames = await getAnimationFrameCount();

     const frameCount = countFrames[0].frameCount;

     for (let i = 0; i < frameCount; i++) {
       const newFilename = `${baseFilename}_${i + 1}`;

       await selectAnimationFrame(i + 1);

       await makeSnapshot(newFilename);

       doc.flatten();

       await saveJPEG(saveFolder, newFilename, 12);

       await revertToSnapshot(newFilename);

       await deleteSnapshot(newFilename);
     }
   });
 } catch (error) {
   console.error(error);
   console.trace(error);
 }

You’ll also need to have your manifest conform to v5 like so:

{
  "host": [
    {
      "app": "PS",
      "minVersion": "24.6.2",
      "data": {
        "apiVersion": 2
      }
    }
  ],
  "manifestVersion": 5,
   "requiredPermissions": {
    "localFileSystem": "fullAccess"
  }
  // ...all other manifest properties
}