flow: operational introspection API — flow/status,result,list,pending + 12 tests

flow/status id -> done|suspended|cancelled|unknown; flow/result id -> value or
error; flow/list -> (id status) per flow; flow/pending -> (id waiting-tag) for
suspended flows (operator view of what each awaits). Pure store introspection.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

plans/flow-on-sx.md

@@ -16,7 +16,7 @@ federation extension via fed-sx for remote-node execution.
 
 ## Status (rolling)
 
-`bash lib/flow/conformance.sh` → **93/93** (all four phases complete)
+`bash lib/flow/conformance.sh` → **105/105** (Phases 1-4 complete; Phase 5 in progress)
 
 ## Ground rules
 
@@ -133,6 +133,20 @@ lib/flow/spec.sx           lib/flow/runtime.sx          lib/flow/store.sx
 - [x] `lib/flow/tests/distributed.sx` — 19 cases: remote-node, failover,
   replication, handoff (including replay-log survival across the move)
 
+## Phase 5 — Operational API + combinator library
+
+The four roadmap phases are complete; this phase rounds out the engine into
+something operators and authors actually use. Accumulation, not a rewrite.
+
+- [x] introspection API — `flow/status id`, `flow/result id`, `flow/list`,
+  `flow/pending` (operator view of what each suspended flow awaits). 12 tests in
+  `tests/api.sx`.
+- [ ] `tap` — side-effecting pass-through node (logging/metrics) that returns input
+- [ ] `recover` — complement to try-catch for the fail-VALUE channel: run node; if it
+  yields `(fail ...)`, run a recovery node on the reason
+- [ ] `map-flow` — run a flow per item of a list, join results (sequential)
+- [ ] `lib/flow/tests/api.sx` — introspection + new combinators
+
 ## Progress log
 
 - **Phase 1 (combinators + sequential runtime).** Flow built as a Scheme prelude