Forward search with tectonic, neovim and zathura

[matkrin]

I would like to make forward search working with tectonic, neovim and zathura.
With the standard Tectonic.toml, the command
tectonic -X build --keep-logs --keep-intermediates creates a pdf named
default.pdf in <root-dir>/build/default/, the auxiliary files are also found
in this directory.

Tectonic.toml:

[doc]
name = "thesis"
bundle = "https://data1.fullyjustified.net/tlextras-2022.0r0.tar"

[[output]]
name = "default"
type = "pdf"

Running forward search from neovim (with the command TexlabForward from
lspconfig) e.g. from the file introduction.tex results in an error because
texlab seems to expect a introduction.pdf file in <root-dir>/build/
according to the log:

DEBUG - < {"method":"textDocument\/forwardSearch","jsonrpc":"2.0","id":2,"params":{"textDocument":{"uri":"file:\/\/\/home\/matthias\/github\/thesis\/src\/introduction.tex"},"position":{"line":8,"character":0}}}
DEBUG - sending message Request(
    Request {
        id: RequestId(
            I32(
                2,
            ),
        ),
        method: "textDocument/forwardSearch",
        params: Object {
            "position": Object {
                "character": Number(0),
                "line": Number(8),
            },
            "textDocument": Object {
                "uri": String("file:///home/matthias/github/thesis/src/introduction.tex"),
            },
        },
    },
)
DEBUG - [FwdSearch] Preparing forward search: document=file:///home/matthias/github/thesis/src/introduction.tex, line=Some(
    8,
)
DEBUG - [FwdSearch] synctex_config=SynctexConfig { program: "zathura", args: ["--synctex-forward", "%l:1:%f", "./build/default/default.pdf"] }
DEBUG - [FwdSearch] root_document=file:///home/matthias/github/thesis/src/introduction.tex
DEBUG - [FwdSearch] root=ProjectRoot {
    compile_dir: "file:///home/matthias/github/thesis/",
    src_dir: "file:///home/matthias/github/thesis/src/",
    aux_dir: "file:///home/matthias/github/thesis/build/",
    log_dir: "file:///home/matthias/github/thesis/build/",
    pdf_dir: "file:///home/matthias/github/thesis/build/",
    additional_files: [
        Url {
            scheme: "file",
            cannot_be_a_base: false,
            username: "",
            password: None,
            host: None,
            port: None,
            path: "/home/matthias/github/thesis/src/_preamble.tex",
            query: None,
            fragment: None,
        },
        Url {
            scheme: "file",
            cannot_be_a_base: false,
            username: "",
            password: None,
            host: None,
            port: None,
            path: "/home/matthias/github/thesis/src/_postamble.tex",
            query: None,
            fragment: None,
        },
    ],
}
DEBUG - [FwdSearch] pdf_name_override=None
DEBUG - [FwdSearch] pdf_path="/home/matthias/github/thesis/build/introduction.pdf", pdf_exists=false
ERROR - Failed to execute forward search: PDF document "/home/matthias/github/thesis/build/introduction.pdf" not found
DEBUG - > {"jsonrpc":"2.0","id":2,"result":{"status":1}}

Neovim config:

-- texlab (installed via cargo)
lspconfig.texlab.setup({
    cmd = { "texlab", "-vvvv", "--log-file", "/tmp/texlab.log" },
    settings = {
        texlab = {
            build = {
                executable = "tectonic",
                args = { "-X", "build", "--keep-logs", "--keep-intermediates" },
                forwardSearchAfter = true,
                auxDirectory = "build/default/",
                pdfDirectory = "build/default/",
            },
            forwardSearch = {
                executable = "zathura",
                args = { "--synctex-forward", "%l:1:%f", "%p" },
            },
        },
    },
})

Also hardcoding
forwardSearch.args = { "--synctex-forward", "%l:1:%f", "./build/default/default.pdf" }
doesn't change the error message. Building from within neovim works fine.

Does texlab not support the fact that there is another subdirectory in
<root-dir>/build/ or am I missing something else? I'm running:

• texlab: v5.17.0
• tectonic: v0.15.0
• neovim: v0.10.0
• zathura: v0.5.6