flow v0.25.0 — graph executor (opt-in, default off)

0.25.0 — 2026-07-27 — graph executor (opt-in, default off)

A graph executor lands in the durable layer, porting LangGraph concepts — not code —
into flow's own Python harness: a checkpoint journal, resume by evidence rather than by
replay, and gates as durable interrupts. It is off by default; nothing changes for an
existing project until FLOW_GRAPH_EXECUTOR=1 is set. Flag-off behavior was verified
byte-identical to 0.24.0 across the full planning ladder, card lifecycle, and workspace verbs.

• Schema band 014+ (graph_execution/graph_checkpoint/graph_step_write/
  graph_interrupt), additive; 013 stays reserved for upstream. This supersedes the
  GAP-MATRIX "work-graph out of scope" red line — flow owns its work-graph now.
• flow harness graph …: session (one execution per project, arbitrated by SQLite,
  not a lock file), record, next, resume, status, cards, finish, abandon,
  gc, lint, root. Manifests are built from typed flags, so card text can never forge
  a gate verdict.
• Topology as trusted data: references/flow-topology.json, pin-verified
  (harness/pins/flow-topology.sha256), loaded only from the skill install dir, and
  validated by a 16-rule graph lint wired into CI. cmd entries are argv arrays limited
  to the new read-only gate verb — mutating verbs are lint-banned from autonomous
  execution.
• /flow gate <stage>|--card C-NNN (new, May-run): mechanical scan only — no unlock,
  no template copy, no durable write. Exit 0 clean / 1 findings / 2 usage or card-not-found.
• Debt-skip fix (applies with the flag off): /flow next no longer re-creates a
  debt-skipped stage, and no longer stalls when that stage's successor file is missing —
  it advances to the first stage that is neither present nor skipped.
• Worktree-aware durable state: a linked worktree resolves to the main worktree's DB so
  parallel cards share one journal. Submodule and --separate-git-dir checkouts keep their
  own DB (git does not expose the checkout there) — documented, not guessed.
• Worktree telemetry survives path spelling: the lifecycle key for a merged worktree
  sink is now canonicalized, and its path travels in its own argument (--src-key-path +
  --src-key-tag). Pre-joining path and tag with # produced a string that Git-Bash path
  translation would not rewrite, so on Windows the rows were keyed differently from the
  sink the harness resolves for itself — written, then invisible to usage and unreachable
  by prune. The same split hit any macOS path reached through a symlink.
• Python floor is measured at 3.7 and enforced by scripts/release-preflight.sh; CI
  pins the interpreter and proves the engine still gates a project with no python on PATH.