Opening sessions from other versions

DataMind Oda saves your chats as session log files on your computer, and each file carries the version of the log format that wrote it. When a file comes from a different version of Oda than the one you are running, Oda works out whether it can open it.

Open a chat from an older version

Oda starts with the first line of the file. That line carries the log's version, and it is enough to sort the file into one of four cases:

• Already current. Oda opens the file as it is.
• Needs an update. The file was written in an older format, and Oda converts it as it opens.
• Not supported. The file's format is one this version of Oda cannot read, for example a file written by a newer version than your app.
• Damaged. The first line itself cannot be read. See Session log problems.

Opening a chat to read it never writes to the file. The next time the chat records something new, Oda:

1. Prepares an updated copy of the chat.
2. Checks the updated copy before saving it.
3. Saves it as a new file next to the original.

The original file stays exactly as it was: same name, same folder, same contents. A chat can therefore have several generations of its log side by side; Session files on your computer explains the names and the folder.

When Oda refuses to open a chat

Some files cannot be opened at all. Oda refuses them rather than guess. A refusal is the same every time you try, nothing is written, and no updated copy is saved. The message names the reason:

• The file was written by a newer version of Oda. session "<id>" uses log format v<version>, but this version of DataMind Oda reads only v<current>: the log was written by a newer version — update DataMind Oda to open it. Update DataMind Oda, then open the chat again.
• The file is older than any shipped conversion. session "<id>" uses log format v<version>, older than the supported v<current>, and this build ships no upgrade path for it. The file is kept as it is.
• The file contains an event this version does not know. session "<id>" contains event type "…" (seq …) unknown to this version of DataMind Oda and not marked ignorable; refusing to interpret the log — it was likely written by a newer version. Update DataMind Oda, or open the file in the version of Oda that wrote it.

An event is passed over only when the writer itself marked it as safe to skip. Oda never marks its own records that way, so a log that carries a newer record is refused rather than read in part.

If a conversion fails part of the way through, Oda says the file was left alone: source v<version> artifact remains unchanged (raw log: <path>).

Oda never converts a file downwards, and it never falls back to an older copy of the log. If the newest version of the file cannot be read, it is refused, not replaced by a different history.

Versions of the log format

• The format has been through five versions, numbered v0 to v4. Current Oda writes v4 and can convert files from v0 through v3 as it opens them.
• The version sits in the file's first line, so Oda can tell how to treat a file before reading the chat itself.
• Oda does not guess: reading a file it does not fully understand could show the wrong history, so it refuses and keeps the file for the Oda version that can open it.

What a session log records

A session log is the lasting record of one chat. At a glance, it holds:

• How the chat started: when it was created, the folder it works in, its parent session if it continues one, and the preset it was started with.
• The conversation: your messages and Oda's answers, including its reasoning.
• Files and images: images in PNG, JPEG, WebP or GIF, and the other files that were part of the chat.
• Tool activity: the calls Oda made and their results; in the current format a tool result is a message of its own.
• Notes Oda keeps for itself: the instructions it was following and which tools it had, so a reopened chat continues correctly.
• Branched chats: when you branch a chat from an earlier point, the copy notes a tool result it did not inherit, because the parent session may have executed it after the fork point.

Questions, answered

Can I open a chat from an older version of Oda?

Yes, when a shipped conversion covers the file's format. Oda converts it as it opens, without touching the file. Some very old files are refused instead; the refusal explains why.

Does opening an old chat change its file?

No. Opening a chat to read it writes nothing, and the updated copy is saved only when the chat next records something new. The original file stays as it was.

Will I still have the old file after Oda updates the chat?

Yes. The updated copy is a new file next to the original, not a replacement. Both stay in the folder; see Session files on your computer.

Why does Oda say the log was written by a newer version?

The chat was made in a newer version of DataMind Oda than the one on your computer. Update DataMind Oda, then open the chat again.

Can an older Oda read chats from a newer one?

No. A file from a newer version is refused, and Oda never converts a file downwards. Update DataMind Oda to open it.

What does "no upgrade path" mean?

The message says this version of Oda ships no conversion for that file's format. The file stays as it is, and opening it again gives the same refusal.

Why does an older chat sometimes take a moment to open?

When Oda saves the updated copy of an older chat, it checks that copy before keeping it. The check can take a moment.

What do the version numbers in a message mean?

They name log format versions: the version that wrote your file and the versions this build reads. Current Oda writes v4 and reads v0 through v3.

Do my images and tool results survive an update?

Yes. When Oda converts a chat, its images, attached files and recorded tool activity are carried into the updated copy.