[FEATURE] allow setting of default title in fast_app()

[mmacpherson]

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Is your feature request related to a problem? Please describe.

Right now, the default title for all (non-htmx) routes is "FastHTML page". I think it would be useful to be able to set a default title that is relevant to one's own project. This would guarantee that a non-sequitur title would not appear if one neglected to add a title to a given route, and would save a little boilerplate for routes where a custom title isn't warranted.

This question has previously been raised here: #208

JPH notes that the standard pattern is to set a title per route, and notes that "it would be a bit tricky to support having titles defined in headers too." Both those points make sense, and JPH is of course best-positioned to make judgments about the difficulty of supporting features.

Describe the solution you'd like

There might be a fast_app(..., title="my site", ...) or fast_app(..., default_title="my site", ...) that effectively replaces the default "FastHTML page" with "my site".

Or the pattern might be to allow the definition of a Title() in the hdrs= argument to fast_app(). (This is allowed now, it just doesn't have the intended effect because the headers defined via hdrs= appear after the default title.)

Example code

For the moment, I have been implementing a default title using Beforeware, as follows:

def inject_title(req, sess):
    req.injects = [Title("my site"), *req.injects]

app, rt = fast_app(..., before=[..., inject_title], ...)

(The code where the contents of req.injects gets converted into headers is here, i.e. in fasthtml.core:_xt_cts().)

This same mechanism might be used, i.e. adding a default_title= value to req.injects.

Alternative 2

Another way might be to, in fasthtml.core:_xt_cts(), flip the order of titles and req.hdrs from:

resp = Html(Head(*titles, *flat_xt(req.hdrs)), ...)

to

resp = Html(Head(*flat_xt(req.hdrs)), *titles, ...)

This way any included Title() in fast_app(hdrs=...) would precede those in titles, and be shown in the browser.

Alternative 3

A .default_title attribute defined via fast_app(), a la def fast_app(..., default_title: str="FastHTML page", ...): ... could be added to the req object, so the line in fasthtml.core:_xt_cts():

if not titles: titles = [Title('FastHTML page')]

might become:

if not titles: titles = [Title(req.default_title)]

Similar implementations
N/A

Problem solved

Mentioned above. Avoids non sequitur titles, minor arguable boilerplate reduction.

Additional context

None.

Confirmation
Please confirm the following:

• I have checked the existing issues and pull requests to ensure this feature hasn't been requested before.
• I have read the project's documentation to ensure this feature doesn't already exist.