feat: enable Marv integration.

[MgnMtn]

Feature

Ensure outputs are compatible with Marv for compatibility with tool.

Tasks

• Marv Output Flag
• Map outputs to Marv's mutation schema.
• The Operator should reflect the approach name
• Derive position at the method extraction stage. I.e., the location in the original source code.
• Try to isolate the change better using diff to give more precise locations to marv

[MgnMtn]

For each approach, create an output for the Marv JSON schema to maintain compatibility.

[SecretSheppy]

I have just added the generic framework to Marv. It will be released at some point this week, but it is currently accessibly through the latest commit. Provided that Multiplex outputs the Marv JSON schema, the results can be shown through Marv by first running:

marv init -f generic

and then filling in the generated .marv.yml file so that the data under the generic section is populated. The completed should look something like this:

marv:
  port: 8080
  review-dir: .marv/reviews

generic:
  framework: marvtest
  marv-json: generic/generic.json
  src-dir: generic

[MgnMtn]

Thanks @SecretSheppy I've filled out

marv:
    port: 8080
    review-dir: .marv/reviews
generic:
    framework: "multiplex"
    marv-json: "output/marv.json"
    src-dir: "output"

Which brings up :

But if I click original_method.java I get back Error Code: NS_ERROR_NET_EMPTY_RESPONSE.

Have I missed something or miss filed it? I'm just running a basic example using the original_method in outputs as the source code for now.

This appears on the server side:

     /opt/homebrew/Cellar/go/1.26.5/libexec/src/net/http/server.go:3464 +0x37c
2026/07/21 16:13:09 http: panic serving 127.0.0.1:53245: runtime error: index out of range [8] with length 8
goroutine 213 [running]:

[SecretSheppy]

This is most likely due to line number and or start/end characters being 1-indexed instead of 0-indexed. If that doesn't solve the problem, I'll have to investigate further.

[MgnMtn]

Thanks! Yep it was a line number indexing discrepancy. Fixing multiplex's output for it.