plans: five rose-ash subsystem plans + three loop briefings

Plans for acl-on-sx (Datalog), flow-on-sx (Scheme), feed-on-sx (APL),
mod-on-sx (Prolog), search-on-sx (Haskell). Each is a 4-phase queue
sitting on its respective guest language, targeting rose-ash needs:
access control, durable workflows, activity feeds, moderation, search.
Federation extension in Phase 4 of each (plugs into fed-sx).

Briefings for the three loops we're kicking off now: acl-loop,
flow-loop, feed-loop. mod-sx and search-sx briefings will follow
once the first three have surfaced any shared infrastructure
worth extracting to lib/guest/.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

plans/agent-briefings/flow-loop.md

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+# flow-on-sx loop agent (single agent, queue-driven)
+
+Role: iterates `plans/flow-on-sx.md` forever. **Durable workflows on Scheme** — the
+call/cc + delimited continuation showcase that justifies pulling R7RS into
+production. art-dag's natural successor: DAG-of-tasks with pause/resume across
+process restarts. fed-sx extension turns local flows into distributed ones.
+
+```
+description: flow-on-sx queue loop
+subagent_type: general-purpose
+run_in_background: true
+isolation: worktree
+```
+
+## Prompt
+
+You are the sole background agent working `/root/rose-ash/plans/flow-on-sx.md`.
+Isolated worktree, forever, one commit per feature. Push to `origin/loops/flow`
+after every commit.
+
+## Restart baseline — check before iterating
+
+1. Read `plans/flow-on-sx.md` — roadmap + Progress log.
+2. `ls lib/flow/` — pick up from the most advanced file.
+3. If `lib/flow/tests/*.sx` exist, run them via `bash lib/flow/conformance.sh`. Green
+   before new work.
+4. If `lib/flow/scoreboard.md` exists, that's your baseline.
+5. Read `lib/scheme/scheme.sx` public API once — that's your substrate.
+
+## The queue
+
+Phase order per `plans/flow-on-sx.md`:
+
+- **Phase 1** — declarative DAG: `defflow`, `sequence`, `parallel`, sync runtime,
+  basic api
+- **Phase 2** — control flow + error handling: `cond`, `retry`, `timeout`,
+  `try-catch`
+- **Phase 3** — **THE SHOWCASE**: `suspend`/`resume` via `call/cc`, persistent
+  store, crash recovery
+- **Phase 4** — distributed nodes via fed-sx (remote-node, handoff, replication)
+
+Within a phase, pick the checkbox that unlocks the most tests per effort.
+
+Every iteration: implement → test → commit → tick `[ ]` → Progress log → next.
+
+## Ground rules (hard)
+
+- **Scope:** only `lib/flow/**` and `plans/flow-on-sx.md`. Do **not** edit `spec/`,
+  `hosts/`, `shared/`, other `lib/<lang>/` dirs, `lib/stdlib.sx`, or `lib/` root.
+  May **import** from `lib/scheme/` only (its public API).
+- **NEVER call `sx_build`.** 600s watchdog. If sx_server binary broken → Blockers
+  entry, stop.
+- **Shared-file issues** → plan's Blockers with minimal repro.
+- **SX files:** `sx-tree` MCP tools ONLY. `sx_validate` after edits.
+- **Worktree:** commit, then push to `origin/loops/flow`. Never touch `main` or
+  `architecture`.
+- **Commit granularity:** one feature per commit. Short factual messages
+  (`flow: retry combinator with exponential backoff + 6 tests`).
+- **Plan file:** update Progress log + tick boxes every commit.
+
+## flow-specific gotchas
+
+- **Continuations must be re-entrant.** Phase 3's `suspend` captures a continuation
+  that may be re-entered after a process restart. That means: no captured file
+  descriptors, no captured sockets, no captured live runtime references that won't
+  survive serialization. State referenced by the continuation must be plain SX data
+  or live in the flow store.
+- **call/cc, not call-with-escape-continuation.** R7RS distinguishes. Use the full
+  call/cc for resume; escape-only continuations cannot be re-entered. Read
+  `lib/scheme/r7rs.md` (or equivalent) to confirm semantics.
+- **`parallel` in Phase 1 is sequential.** Don't try threading until Phase 3+. Just
+  evaluate branches in order, collect results, return joined value. Document the
+  semantics clearly so users don't assume true concurrency.
+- **Retry doesn't retry continuations.** If a node has already suspended, retry on
+  resume doesn't re-run it from scratch — it resumes. `retry` only applies to
+  exceptions raised before suspend. Be explicit in the API.
+- **Cancellation invalidates the continuation.** `(flow/cancel id)` must remove the
+  stored continuation so a stale `resume` cannot wake it. Document semantics.
+- **Timeouts in pure SX are tricky.** Without a scheduler, `timeout` is a budget on
+  step count or wall-clock probed at safe points. Pick one approach (probably step
+  budget for determinism) and document.
+
+## General gotchas (all loops)
+
+- SX `do` = R7RS iteration. Use `begin` for multi-expr sequences.
+- `cond`/`when`/`let` clauses evaluate only the last expr — wrap multiples in `begin`.
+- `env-bind!` creates a binding; `env-set!` mutates an existing one (walks scope chain).
+- `sx_validate` after every structural edit.
+- `list?` returns false on raw JS Arrays — host data must be SX-converted.
+
+## Style
+
+- No comments in `.sx` unless non-obvious.
+- No new planning docs — update `plans/flow-on-sx.md` inline.
+- Short, factual commit messages.
+- One feature per iteration. Commit. Log. Push. Next.
+
+Go. Start by reading the plan; find the first unchecked `[ ]`; implement it.