writeonce/docs/stories/language-runtime-database/26-blue-green-deploy.md
shoney.arickathil 5521d21a84 docs: pending iterations renumbered by dependency + priority
- developer directive: pending iteration IDs now ARE the priority order;
  LANDED iterations keep historical numbers (code comments and commit
  history cite them — records, not a queue); 8/11 (the half-landed
  arc), 17 (parked, artifacts on a branch), 18 (next, artifacts named)
  also frozen
- mapping (recorded in 00-story): 19<-20 Float+Bytes, 20<-9c attach,
  21<-9d keypair, 22<-9e benchmarks, 23<-9f io_uring WAL, 24<-19 chat,
  25<-10 services, 26<-12 blue-green, 27<-9g query corpus,
  28<-14 skillhost, 29<-13 metaprogramming
- 11 story files renamed; every doc reference re-numbered (word-boundary
  sweep for the lettered 9x ids, phrase-level for numeric ones); the
  iterations table rewritten with Seq == priority and "(was N)" notes;
  story-scoped link check: zero broken
- merge-recovery folded in: the partial master merge had dropped the
  chat story, the fibers exploration note, the arc spec+plan, the
  framework-v2 plan, and the iteration-17 spec+plan — all restored from
  their branches and renumbered consistently

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-08-20 14:31:09 +02:00

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# Iteration 26 — blue-green in-runtime deployment
> Format: `product/story-iteration-template`. Part of
> [Story — one language, one runtime, one database, one binary](00-story.md).
## Goals
- The story's closing promise: the running binary updates its own code.
Two fixed VM slots (activity alternating); a proposal pipeline —
propose → approve → in-runtime compile → additive schema migration →
load → health → atomic switch — with the previous version staying
resident as the instant rollback target.
- The developer drives it remotely: `wo remote pull / propose / diff /
approve / rollback / status` over a loopback management transport,
every stage streaming live and WAL-audited.
## Acceptance Criteria
- What to achieve?
- **Given** a running fixture app and an additive code+schema change,
- **when** the developer proposes and approves it,
- **then** the deploy completes with zero dropped requests (in-flight
work — including parked fibers — drains on the old slot through
iteration 11's unwind path), and the binary's embedded source
trailer matches the new active version afterward.
- What to achieve?
- **Given** a failure at any pipeline stage (compile diagnostic,
destructive-change rejection, load failure, health failure, drain
timeout),
- **when** it occurs,
- **then** the active slot keeps serving untouched, the failure is
visible in the SSE stream and the WAL trail, and a destructive
change was rejected at propose time naming the offending
declaration.
- What to achieve?
- **Given** a completed deploy,
- **when** `wo remote rollback` runs,
- **then** the previous version serves again in under one second with
no compile and no data change — additive-only migration guarantees
old code runs correctly against the migrated schema.
- What to achieve?
- **Given** kill -9 during COMPILING / MIGRATING / SWITCHING /
trailer-rewrite,
- **when** the unit restarts,
- **then** it serves one consistent version and the WAL shows whole
migrations only.
## Out Of Scope
- Script-based/destructive migrations, in-runtime editing workspace,
MCP/agent wrapper over the management plane — all recorded follow-ups.
- New scheduler work — fibers landed in iteration 11; this iteration's
drain unwinds parked fibers through 11's shutdown path, it does not
extend it.
## Info
- Approved spec: `docs/superpowers/specs/2026-08-03-blue-green-vm-design.md`;
its implementation plan is deliberately authored only after iterations
9–10 ship (prerequisites: a catalog to diff, HTTP machinery to build on).
- VMs own code; the engine owns data — the separation that makes the
switch cheap and rollback unconditional.
## Proposed Solution
- Author the implementation plan from the approved spec once iterations
9–10 land, then execute it (slots, deploy state machine, additive
differ, management surface + SSE, `wo remote` verbs, crash battery).