Merge pull request #10 from mhoennig/22-multi-repo

ADR 0009 and step 22 plan: one Werkator instance serves a set of repositories # Conflicts: # docs/plan/22-multi-repo.md # docs/prs/2026-09-01-PR#6-werkdock-bootstrap.md
2026-09-02 07:22:59 +02:00
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+# One Werkator Instance Serves a Set of Repositories
+
+**Status:**
+- proposed: 2026-09-01
+- accepted: 2026-09-01
+- rejected: -
+- superseded: -
+
+**Decision [accepted]:** The founding tenet "one instance per repository" is revised to "one instance per repository *set*": a Werkator instance aggregates self-contained repositories listed in an instance registry, sharing one service, one port, one UI, one watcher schedule, and one global executor cap.
+Implementation is planned as `docs/plan/22-multi-repo.md`; this ADR records the decision and its shape, not the code.
+
+## Context and Problem Statement
+
+"One instance per repository" (docs/Werkator-Konzept.md) does not scale even to two repositories on a Hostsharing Managed Webspace: building Werkbaum next to Werkator on mih34 would need a second service, a second assigned port, a second tunnel or domain, a second UI and metrics page.
+Every repository multiplies operations while the instance-level resources could be shared.
+
+### Technical Background
+
+Everything repository-specific already lives inside the repository or is keyed by it: machine config with secrets, build results, auto-build slots, worktrees, and buildenvs under `.git/werkator/`; the artifact store under a per-repo key.
+An instance can therefore aggregate repositories without absorbing their state — adding or removing a repository is a registry entry, never a data migration, and single-repo mode stays the degenerate case (a registry of one, implicitly the current working directory).
+
+## Considered Options
+
+* One instance per repository set (registry + aggregation) — chosen
+* A federation dashboard proxying several single-repo instances
+* Status quo: one instance, one repository
+
+### One Instance per Repository Set
+
+Good:
+
+- One service, port, UI, tunnel/domain, metrics page for any number of repositories.
+- Repositories stay self-contained; per-repo secrets, history, and pinning semantics are untouched.
+- Global concurrency control across all repositories.
+
+Bad:
+
+- The repo dimension must be threaded through executor pools, watcher cycle, routes, and UI — the largest refactor since the rewrite (mitigated by a behavior-preserving `RepoContext` session first).
+- Instance-level and repo-level configuration must be split cleanly (see below).
+
+### Federation Dashboard over Single-Repo Instances
+
+Rejected: less invasive, but it keeps N services, N ports, and N tunnels — it solves only the UI aggregation, not the operations burden that motivated the change.
+
+### Status Quo
+
+Rejected: on a webspace, ports and domains are the scarce, manually assigned resource; per-repository services do not scale there.
+
+## Decision Outcome
+
+One instance per repository set, with the configuration split decided 2026-09-01:
+
+- **Instance config** lives in `~/.werkator.yml` in the home directory of the user running the instance — one instance per OS user, matching the platform model. It carries `server.*` (port, domain/public base URL, nginx), the repository registry, the control token, the global `executor.maxConcurrent`, and the watcher schedule. The file name stays `.werkator.yml` in all three locations; the location carries the meaning.
+- **Repo defaults** may live in the home file, but only in an explicit `defaults:` block, merged *below* every repository's own layers (home defaults → committed project config → repo machine config → branch layer); pinning semantics are unchanged. Accepted cost: secrets may then live in two places.
+- **Repo config** stays in each repository: the committed `.werkator.yml` and the machine config in its `.git/werkator/`.
+- Instance keys found in a repo's machine config are ignored with a warning naming both files once a home config exists — never merged silently.
+- When a home config with a registry exists, `werkator server` serves the registry regardless of the current directory; without one it serves the current directory exactly as before.
+- Repository names (routes, UI) default to the directory basename, are overridable per registry entry, and duplicates abort the start loudly.
+
+Consequences: `docs/Werkator-Konzept.md` and AGENTS.md change their wording when the implementation lands (plan step 22 sessions B–D); until then this ADR documents the target and the existing behavior remains accurate.