Beagle SCM

JGET-012: relative submodule url (../sub) not resolved against the parent source

jab get of a git parent whose .gitmodules declares a RELATIVE submodule url (url = ../sub) passes it to the sub fetch without resolving it against the parent SOURCE URI, so the fetch targets a nonexistent project (HOMENOPROJ / "peer advertised no usable ref"), the sub is absent and the get exits 1. Native resolves ../sub against the parent URI (the SUBS-020 rule). Part of JGET-001; method Issues.

Input

Context

• Native beagle/test/get/50-file-subs-git-relative (SUBS-020, relative ../sub).
• Repro: git parent with .gitmodules url=../sub; jab get <parent> → HOMENOPROJ / no usable ref, sub absent. Evidence ~/todo/JSGET-cases/c50/wk/c3a.err.
• Root: the sub-mount candidate builder takes the declared url verbatim; no relative-to-parent-source resolution (be/shared/submount.js).

Goals

• A relative .gitmodules url is resolved against the parent source locator before fetch (matching native SUBS-020); absolute urls unchanged.

Constraints

• Use the URI binding's path-merge, not string concat. Repro-first. Sequence after JGET-006/JGET-007 (sub mount must work for non-relative first).

WIP

Design decisions

• Resolve the declared url: if relative, merge against the parent source URI (scheme/host/path) to form the sub locator; keep absolute urls as-is. Slot it as a candidate before the raw declared-url fallback.

TODOs

• Repro test: parent with url=../sub → sub mounts.
• Add the resolution — STILL ABSENT: gitmodules.js urlOf/declaredUrl return the raw string; mount (submount.js:212) feeds it verbatim to localSourceUri/tryFetch, where a relative ../sub resolves against jab's CWD (the clone wt), not the parent source. Merge a relative url against opts.source (scheme/host/path) via the URI binding, slotted before the raw-url fallback.
• Spec gate in be/test/get (case-50 shape; native oracle retired by TEST-003).

Blockers and bummers

• Depends on the sub-mount path working — JGET-008 retired; only the JGET-007 wire half remains.
• NB sameSourceUris (SUBS-047) may MASK this for a worktree-git parent (the <path>/<subpath> candidate mounts before the relative url is ever tried) — the repro must use a source shape with no same-source candidate (e.g. a bare .git parent).

Outcome

• (open) Filed 2026-06-29.