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mcpx: pass the scope-resolved root as rootUri/workspaceFolders at initialize, so workspace servers (gopls) get a real workspace #1993
Description
Relocated from dezren39/darwin-nix#819 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 sends no workspace information when it initializes a server: no rootUri, no workspaceFolders (grep across internal/mcpclient and internal/pool — none). Workspace-oriented servers therefore start without a workspace session even when mcpx knows exactly which repo the caller is in.
Concrete evidence (live fleet, 2026-10-25): gopls behind mcpx works file-by-file — its file-argument tools load the file ad hoc as a "command-line-arguments" package — but it is not a module workspace session: go_package_api on a module path returned empty after 156 s. Two missing pieces combine here: the process cwd is static (the spawn-cwd issue), and the initialize handshake carries no root even if the cwd were right.
Proposed design
When mcpx has a scope-resolved root for an instance (repo/worktree scope resolution already computes it), include it in the initialize params for that server instance:
rootUriset to the resolved root, andworkspaceFolderscontaining that root,
for servers that declare workspace support in their initialize negotiation. Servers that don't advertise/accept it must be unaffected (send only what the negotiated protocol version and server capabilities allow).
This is step 3 of the 2026-10-25 per-project design note. It builds on the spawn-cwd issue #817, which introduces the resolved-root plumbing this issue reuses; the ${mcpx.root} substitution issue #818 is the config-level companion. Order: spawn-cwd/substitution first, this after — flipping gopls to "scope": "worktree" only becomes fully effective once the workspace reaches the server both via cwd and via initialize.
Acceptance criteria
- For an instance with a scope-resolved root, the initialize request mcpx sends includes
rootUri/workspaceFoldersnaming that root (demonstrated by a captured handshake or a test double server that records initialize params). - Servers that don't negotiate workspace support initialize exactly as before.
-
global-scoped instances (no resolved root) send no rootUri/workspaceFolders — no fabricated daemon-cwd root. - With gopls at
"scope": "worktree"behind the fixed spawn cwd,go_package_apion a module path returns the module's API promptly (the 156 s empty result does not recur). - Tests cover: root present for repo/worktree scopes, absent for global scope.
Activity
developing-today commentedon Oct 28, 2026
CODE-918
dezren39 commentedon Oct 28, 2026
History carried over from dezren39/darwin-nix#819 (verbatim, oldest first):
@dezren39 · 2026-10-26T02:47:18Z
Intake review
Still live (verified this run): a code search for
rootUriacross developing-today/code returns zero hits, and no merged PR in either repo adds workspace information to the mcpx initialize handshake. Not closed.Related — set order: #817 (step 1, spawn cwd) → #818 (step 2, substitution) → #819 (this, step 3). This one depends on the resolved-root plumbing from #817; the issue's own ordering note says flipping gopls to
"scope": "worktree"only becomes fully effective once both the cwd (#817) and the initialize root (this) reach the server.Cross-repo note: mcpx source lives in developing-today/code
pkgs/mcpx(nopkgs/mcpxin this repo — verified this run); the implementation PR lands there, this issue tracks the set from the fleet-config side.Notes / risks: capability gating is the risk — servers that don't negotiate workspace support must initialize byte-identically to today, and
global-scoped instances must not gain a fabricated daemon-cwd root. The end-to-end criterion (goplsgo_package_apireturning promptly) needs the #817 fix in place to be meaningful.Suggested approach: after #817, thread the resolved root into the initialize params for repo/worktree-scoped instances only, gated on the negotiated protocol/capabilities; cover root-present (repo/worktree) and root-absent (global) with a test-double server that records initialize params.
🤖 Fleet monitor intake enrichment — labels normalized and
meta/enrichedapplied this pass.@dezren39 · 2026-10-26T11:28:54Z
Design consolidated and moved home. This issue's design (and its companions #817/#818) 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 — §5 adopts the rootUri/workspaceFolders proposal and decides the negotiation question: both fields plus the
workspace.workspaceFoldersclient capability are sent for every era whenever a scope-resolved root exists (initialize params are extensible; non-consuming servers ignore them), and initialize stays byte-identical to today when no root exists. Implementation is tracked in #959 (slice 3) for the handshake, and the live goplsgo_package_apiproof is the acceptance of slice 4, #961 (fleet config flip, deliberately last).Leaving this issue open deliberately: closing the nix-side originals with pointers is the re-homing pass's acceptance criterion (#309), and this comment is the pointer that pass needs.
dezren39 commentedon Oct 29, 2026
Closed as duplicate of #959 — the code-side issue already carries this work
Triage verdict (queue task
2899, workerrepo-worker-code, originopenchamber-scheduled-lane), againstdeveloping-today/codemain@4d157755.#959 "mcpx: initialize sends rootUri/workspaceFolders for scope-resolved instances" was filed in this repo on 2026-10-26, two days before this issue was relocated from dezren39/darwin-nix#819 (2026-10-28). It is slice 3 of decision record 0004 (
pkgs/mcpx/docs/decisions/0004-scope-resolved-roots.md, merged on main via PR #957) and quotes the nix#819 acceptance criteria verbatim, so nothing from the original filing is lost by closing this copy. Pointers added both ways (#959 ← this issue).Scope confirmation — the premises still hold on main
Client.initializeParams()(pkgs/mcpx/internal/mcpclient/client.go:422-429) sends exactlyprotocolVersion,capabilities,clientInfo— norootUri, noworkspaceFolders, so a workspace server still starts without a workspace session.SetRoots(client.go:921) exists, therootsclient capability is declared (modern.go:80-83), and mcpx answers a server'sroots/list(relayed from the caller,modern.go:287-303). What is missing is putting the scope-resolved root into the initialize request itself.ResolvedScopeplumbing) is open,status/needs-triage; nothing namedResolvedScope/scope root exists inpkgs/mcpx/internalyet. So no implementation could be merged against this issue today either.Two things worth folding into #959 (posted there too)
2026-07-28) dropped the roots feature and mcpx already declaresroots: {}there (modern.go:64-65,80), so sendingrootUri/workspaceFoldersin a 2026-07-28 initialize is spec-questionable and untested; the stricter wording here is the safer default until someone verifies it.go_package_apiacceptance needs the child-cwd half as well, which is mcpx: spawn repo/worktree-scoped instances with the child cwd set to the resolved scope root #1989 (open). Note that mcpx: ResolvedScope plumbing + spawn cwd = resolved scope root #958's title ("ResolvedScope plumbing + spawn cwd = resolved scope root") appears to claim that same spawn-cwd work, so mcpx: ResolvedScope plumbing + spawn cwd = resolved scope root #958 and mcpx: spawn repo/worktree-scoped instances with the child cwd set to the resolved scope root #1989 look like duplicates of each other for the cwd half — flagged for whoever owns them, not resolved here.Dedupe pass record
Searched open+closed for
rootUri,workspaceFolders,workspace session,gopls. Same-subject issues: #959 (this work, canonical), #958 (slice 1 prerequisite), #961 (slice 4: gopls at worktree scope + live proof), #1991 (closed:${mcpx.root}substitution), #1989 (open: spawn cwd). No other copy of this issue's subject exists.No implementation was done here, as scoped. Closing as duplicate with this pointer; #959 keeps the work.
dezren39 commentedon Oct 29, 2026
🤖 Agent note · closed as duplicate
repo-worker-code(openchamber scheduled lane), queue task2899(kind triage, originopenchamber-scheduled-lane)initializeParams()sends norootUri/workspaceFolders(internal/mcpclient/client.go:422-429); roots plumbing exists only in the answer direction (SetRoots,roots/listrelay);ResolvedScope(mcpx: ResolvedScope plumbing + spawn cwd = resolved scope root #958) still absent, so mcpx: initialize sends rootUri/workspaceFolders for scope-resolved instances #959 remains correctlystatus/blocked.rootUriquestion (mcpx: initialize sends rootUri/workspaceFolders for scope-resolved instances #959 says every era, this copy said negotiate-gated) needs a decision before implementation.work/assigned,queue/claimed,status/in-progressremoved;duplicate+meta/duplicateadded.