Separate shared pstack workflows from harness and lane adapters

[thisguymartin]

Refs #3, #34, #35. Historical installed-test debt is tracked in #36.

What changed

pstack-flex now treats the parent coding harness and the lane provider as separate inputs. One shared skill tree uses a small harness table, a shared configuration reader, and explicit provider launch boundaries. Adding a harness means adding metadata and its tool/instruction mapping, without copying skills or setup.

• harnesses.ts owns native routing, paths, identity, session, and launch metadata. pstack-context reads the selected configuration once; setup uses --paths-only so broken sheets can still be repaired.
• Descriptor parsing, scope resolution, and model refusal are shared. Project sheets still replace global sheets; linked worktrees use the primary checkout's sheet.
• OpenCode remains beta. Fresh deny-first lane agents prevent ambient settings from restoring tools. Neither lane mode gets shell access; writers can edit inside their worktree. Preflight rejects unsupported effort variants and wrapped model routers, with typed failure results.
• Kept upstream workflow bodies. Only the adaptation preamble and setup skill body change; the historical mapping filename stays so upstream links resolve.
• Deleted seven duplicate/completed Markdown files: README-UPSTREAM.md, UPSTREAM-FLEX.md, docs/LANES.md, docs/USAGE.md, docs/gateway-model-probes.md, and both completed docs/plans/ documents. Durable verification debt moved to Issues.
• Ordinary documentation is six files: README for installation, reference for diagnosis, UPSTREAM for ownership/sync, NOTICE for attribution, CHANGES for the intentional fork changelog, and LIVE-GATE for installed verification. The other Markdown is consumed skill/agent/hook content or the PR template.

History is one commit, 63e4b337504abb5037c977917b731b2d3d11da09, after b49b15d. Upstream and the independently merged OpenRouter work remain intact. PR base is now main.

Verification

• Bun tests, strict typecheck, static invariants, and plugin validation pass.
• The exact candidate is installed in every affected harness with the complete required gate exercised.
• The changed behavior passes from each real user surface, including setup writes/rollback and mixed dispatch.
• Installed version, action, and observed partial results appear below.

bash scripts/check.sh: 256 tests pass, strict typechecks pass, manifest/static checks pass, and both Claude plugin validators pass. GitHub CI also passes for this SHA: 254 tests pass and the two installed OpenCode tests are explicitly skipped because that CLI is absent.

Behavior comparison: 36/36 existing non-OpenCode launch contracts are identical across parent/provider/access combinations against the rebased pre-cleanup feature. Six OpenCode cases intentionally change permissions and agent environment. This is a launch-contract comparison, not a substitute for live provider behavior.

Installed OpenCode permission checks passed on 1.18.9 and were rerun on 1.18.34: both modes deny shell/task/web/skill tools despite explicit ambient allows; read-only cannot edit; writers can edit inside the worktree and cannot write outside it. These use the actual CLI without model/network calls.

Interrogate completed with Fable 5.1, GPT-6 Astra, and Opus 5.5. Grok 4.7 was a named unavailable-CLI dropout. Consensus permission findings and substantive configuration/routing findings were fixed. Final frozen-SHA confirmation found no remaining substantive defect. Lead verdict.

Live evidence: Claude Code

Harness: Claude Code 2.1.291
Installed: local pstack 1.5.0 plugin directory @ 63e4b337504abb5037c977917b731b2d3d11da09
Surface: fresh interactive CLI in a synthetic Git repository; older pstack plugin disabled for this invocation
Action: /pstack:setup-pstack, restricted to path inspection before assignments/probes/writes
Observed: loaded the candidate skill; called its packaged pstack-context --parent claude --paths-only; exit 0; correct global/project paths and scope choices
Result: pass for path inspection; complete setup/rollback/mixed-panel gate not run
Transcript: local Claude session 1112544d-8e95-440f-af7f-f59be4efdd1d

Live evidence: Codex

Harness: Codex 0.160.1
Installed: pstack 1.5.0 via isolated local marketplace @ 63e4b337504abb5037c977917b731b2d3d11da09; packaged files compared with candidate
Surface: fresh interactive CLI, isolated CODEX_HOME, synthetic Git repository
Action: setup-pstack, restricted to path inspection before assignments/probes/writes
Observed: discovered and read installed setup skill; ran packaged pstack-context --parent codex --paths-only; correct isolated global/project paths and scope choices
Result: pass for discovery/path inspection; hook trust warning and complete setup/rollback/mixed-panel gate remain unverified
Transcript: local Codex session 01a10f9c-c460-7f13-ac06-c28d055479cc

Live evidence: OpenCode beta

Harness: OpenCode 1.18.34
Installed: candidate skill path and opt-in instructions @ 63e4b337504abb5037c977917b731b2d3d11da09
Surface: fresh interactive CLI, isolated XDG_CONFIG_HOME, synthetic Git repository
Action: setup-pstack path inspection before probes/writes
Observed: default-model session discovered setup-pstack and read candidate harness metadata after correcting its initial relative path; no context-helper result returned. This attempt was manually cancelled as inconclusive. A separate explicitly selected OpenAI GPT-6.1 Sol parent session failed with Token refresh failed: 401.
Result: discovery observed; final parent context/setup/dispatch gate not run
Transcripts: local OpenCode sessions ses_ef0633ba2ffearr5OIuoUUgdn2 and ses_ef05aa05dffeHT6B4u9cPEfBYv

Remaining required gate: opt-in/opt-out, actual setup writes and unchanged reruns, invalid-probe rollback, installed worktree scope behavior, native/external mixed panels, and affected background/cancellation flows in every parent. No merge, tag, release, or rollout until those pass. This PR remains draft.