mdBook 0.5 support

[gorbak25]

There was an major release of mdbook today. This preprocessor is incompatible with the new version.

 INFO Book building has started
[2025-11-18T14:52:40Z ERROR mdbook_admonish] Fatal error: Unable to parse the input
[2025-11-18T14:52:40Z ERROR mdbook_admonish]   - Unable to parse the input
[2025-11-18T14:52:40Z ERROR mdbook_admonish]   - invalid type: null, expected any valid TOML value at line 1 column 147
 WARN Error writing the RenderContext to the backend, Broken pipe (os error 32)
ERROR The "admonish" preprocessor exited unsuccessfully with exit status: 1 status

[tommilligan]

Thanks for the report - agree this looks like a breaking change in the PreprocessorContext type, we probably need to update our mdbook library dependencies and release a version bump ourselves.

As well as Cargo.toml, we may need to update the mdbook binary version installed in CI to test throughout. If so, this will be a major version bump for us. If we don't actually need to bump mdbook binary, it means we can make this a back compatible change and just do a minor release instead.

I won't be able to do this for a while, happy to review PRs from anyone else.

[CoralPink]

Hi!

I had some free time today, so I tried it locally.
I'm a bit hesitant to make a PR, but builds using mdbook v0.5.1 have been successful (...probably).

https://github.com/CoralPink/mdbook-admonish/tree/mdbook-v0.5.x
CoralPink@8676c3c

I think it's almost done, but there are parts I just can't manage on my own 😿
(Regarding the two sections marked FIXME!)

Would you be able to help me with something?

[tommilligan]

Thanks, this is looking good. Please do put it up as a PR even if it still needs some work, it's easier for me to review there 🙂

Comments from me on code:

• agree we need to inline the id generation code from mdbook, that's fine. Maybe for clarity it could live in a separate module called content_id or something.
• Why do we need to use static values/is there a change in mdbook that means we can't load the config any more?
• could you change supported.unwrap to supported.unwrap_or_default

Other main thing is - does this still work with mdbook binary 0.4.x for you locally? (great work getting it running with 0.5.x!)

[CoralPink]

Thanks for the comment!
First off, I'm relieved to hear you took it in a positive light 😄

I know it's pretty half-baked, but I'll go ahead and make the PR (#234) anyway.

Well... it's kind of weird to say this,
but today is a holiday in Japan and the weather is absolutely gorgeous, so I'm thinking of going out.

Would it be okay to continue tomorrow or sometime after...? 😣

[CoralPink]

Regarding whether it works with mdbook binary 0.4.x, at least in its current state, it will result in an ERROR.

2025-11-24 12:40:20 [INFO] (mdbook::book): Book building has started
[ERROR mdbook_admonish] Fatal error: Unable to parse the input
[ERROR mdbook_admonish]   - Unable to parse the input
[ERROR mdbook_admonish]   - missing field `items` at line 1 column 841446
2025-11-24 12:40:20 [ERROR] (mdbook::utils): Error: The "admonish" preprocessor exited unsuccessfully with exit status: 1 status

[tommilligan]

Would it be okay to continue tomorrow or sometime after...? 😣

Yes of course! Whenever you have time it's appreciated.

Thanks for confirming about 0.4.x of mdbook erroring after the upgrade also.