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mcpx: spawn repo/worktree-scoped instances with the child cwd set to the resolved scope root #1989
Description
Relocated from dezren39/darwin-nix#817 on 2026-10-28 (placement audit): mcpx's single source lives in developing-today/code (pkgs/mcpx); re-home tracked at #309. Original body below; issue references inside it are historical (dezren39/nix numbering).
Problem
mcpx scopes choose which process serves a caller, but nothing tells that process where the caller is.
Scope keys already resolve the caller's cwd to a git root: internal/config/scope.go (CallContext, Scope.Key()) yields repo:<git-common-dir> / worktree:<top-level> using the native git discovery in internal/config/gitdiscover.go. But instance spawn ignores that resolution: internal/pool/pool.go dial() builds StdioOptions{Cwd: p.cfg.Cwd} — the config's static string, verbatim — and internal/mcpclient/stdio.go sets cmd.Dir = opts.Cwd. A repo- or worktree-scoped server therefore still runs in the daemon's cwd.
Concrete casualty (observed live, 2026-10-25, fleet config of 16 servers): gopls is a workspace server whose workspace is its process cwd. Scoped per-checkout it would still run in the daemon's cwd, so it loads files ad hoc ("command-line-arguments" package) instead of as a module workspace session.
Proposed smallest design
When a server's scope is repo or worktree and its config cwd is empty, spawn the instance with Dir = the resolved scope root (the common-dir's worktree / the checkout top-level) instead of the daemon's cwd.
This needs the scope resolution to hand the pool the root, not just the opaque key string: return the resolved root alongside the key from Scope.Key(), or recompute it via locateGit at spawn time. One branch in pool.dial().
Explicit config cwd always wins — the scope root is only the default when cwd is unset.
Why this order
This is step 1 of the per-project design note (2026-10-25). With it, "mcpx": {"scope": "worktree"} on gopls becomes a real per-project workspace server: one gopls per checkout, rooted in that checkout. Flipping scopes before this lands only multiplies processes for little gain, so config scope flips wait for this issue.
Related: #818 — the ${mcpx.root} / ${mcpx.cwd} substitution issue (companion, step 2) — and #819 — the initialize rootUri/workspaceFolders issue (step 3, builds on the root resolution here).
Acceptance criteria
- A
worktree-scoped server with no configcwdis spawned with its working directory set to the caller's checkout top-level; arepo-scoped one to the resolved worktree of the common dir. - Two callers in different checkouts of the same repo get distinct
worktree-scoped instances rooted in their own checkouts;reposcope keeps sharing one instance per common dir. - An explicit config
cwdoverrides the scope root in all cases. -
global/cwd:/sessionand other scopes are unchanged. - A
worktree-scoped gopls answers a package-level query (e.g.go_package_apion a module path) with the module's real API instead of an empty result. - Tests cover the spawn-cwd decision (scope root vs explicit cwd vs daemon cwd fallback).
Activity
developing-today commentedon Oct 28, 2026
CODE-914
dezren39 commentedon Oct 28, 2026
History carried over from dezren39/darwin-nix#817 (verbatim, oldest first):
@dezren39 · 2026-10-26T02:47:00Z
Intake review
Still live (verified this run): no merged PR in this repo or in developing-today/code implements scope-root spawn cwd for mcpx; the spawn path cited in the evidence (
internal/pooldial()→ static configCwd) is unaddressed. Not closed.Related — this is a set, in order: #817 (this, step 1: spawn cwd) → #818 (step 2:
${mcpx.root}/${mcpx.cwd}substitution) → #819 (step 3: initializerootUri/workspaceFolders). One origin set per the fleet cross-repo rule; downstream work references this set rather than re-filing.Cross-repo note: the mcpx source no longer lives in this repo (no
pkgs/mcpxhere — verified this run); it lives in developing-today/codepkgs/mcpx, which this repo builds from themcpx-srcinput. The implementation PR lands there; this issue tracks the set from the fleet-config side.app/mcpxwas coined on this repo for this set.Notes / risks: priority/high as the set's blocker — #818 and #819 both reuse the resolved-root plumbing this introduces, and the live casualty (gopls loading files ad hoc,
go_package_apiempty after 156 s) persists until it lands. Explicit configcwdmust always win;global/cwd:/sessionscopes must not change.Suggested approach: return the resolved root alongside the opaque scope key (or recompute via
locateGitat spawn), defaultDirto it only forrepo/worktreescopes with empty configcwd, and pin the decision with the spawn-cwd tests in the criteria.🤖 Fleet monitor intake enrichment — labels normalized and
meta/enrichedapplied this pass.@dezren39 · 2026-10-26T11:28:55Z
Design consolidated and moved home. This issue's design (and its two companions #818/#819) now lives in the mcpx source repo as decision record 0004: PR #957 (
pkgs/mcpx/docs/decisions/0004-scope-resolved-roots.md).Position: the record fully supersedes this issue as a design document — the proposed design is adopted as written, and §1–§3/§6 of the record decide the plumbing (a
ResolvedScopesibling toScope.Key, root as a pure function of the key, pool learns the root at Acquire). Implementation is tracked in #958 (slice 1), whose acceptance criteria carry this issue's over verbatim (the live gopls proof sits in slice 4, code#961, where the full stack exists).Leaving this issue open deliberately: closing the nix-side originals with pointers is the #309 re-homing pass's acceptance criterion (tracked here as #309), and this comment is the pointer that pass needs.
dezren39 commentedon Nov 1, 2026
🤖 Agent note · handed off
dezren39 commentedon Nov 1, 2026
🤖 Agent note · handed off
mcpx statusand the spawn log line.dezren39 commentedon Nov 2, 2026
🤖 Agent note · handed off
dezren39 commentedon Nov 2, 2026
Claimed as queue task 2895 (triage). Deduping against the #957/#958 slice chain and confirming spawn-cwd scope against current main.
dezren39 commentedon Nov 2, 2026
Triage verdict: ALREADY DONE — implemented by PR #3925
Verified against fresh state (
origin/main@0e26fa4b3):77970ebbc; implementation commitff15803fd, in mainline history). Its message explicitly refs this issue: spawn-cwd criteria 1–4 covered.ResolvedScope{Key, Root, Degraded}+Scope.Resolveinpkgs/mcpx/internal/config/scope.go; poolSpawnCwd(config cwd, else resolved root, else unset); root carried through instance handoff andmcpx status.Closing as implemented.