Wave 49 tick#2: ALLOWED_STEPS calc_engaged extension

Date: 2026-05-12 Branch: feat/jpcite_2026_05_12_wave49_allowed_steps_calc_engaged PR: (to be filled after push) Base: main @ 8fe65074d

Context

Wave 49 G1 organic funnel is a 5-stage cohort:

landing → free → signup → topup → calc_engaged

Prior PRs landed the 4-step baseline (PR #4) plus the client-side wiring of the 5th step (PR #195) — the cost-saving calculator page site/tools/cost_saving_calculator.html loads /assets/rum_funnel_collector.js, which inferStep() maps /tools/cost_saving_calculator* → "calc_engaged".

The previous tick (#8) observed:

POST /api/rum_beacon  body={step:"calc_engaged",...}  → HTTP 400
Response: "Invalid beacon shape"

Root cause: server-side gate ALLOWED_STEPS in functions/api/rum_beacon.ts still listed only the 4 baseline steps. isValidBeacon() returned false because b.step was not in the Set, dropping every calc_engaged beacon at the edge and collapsing the 5-stage funnel to a 4/5 observable state.

Change

Additive 1-line server-side extension. The ALLOWED_STEPS Set adds a 5th member.

Diff (1 file, +1 line)

--- a/functions/api/rum_beacon.ts
+++ b/functions/api/rum_beacon.ts
@@ -73,6 +73,7 @@ const ALLOWED_STEPS = new Set([
   "landing",
   "free",
   "signup",
   "topup",
+  "calc_engaged",
 ]);

The validator (isValidBeacon) and all other gates remain unchanged — the 4KB payload cap, bot-UA filter, CORS apex regex, and 400/413 paths behave identically.

Test

New file: tests/test_rum_beacon_calc_engaged.py (~120 LOC, 4 tests).

Structural rather than runtime (workerd spin-up would add 60-90s for no incremental class of bug — companion test tests/test_cf_pages_rum_beacon.py already covers wire shape):

1. test_allowed_steps_now_includes_calc_engaged — verifies the new "calc_engaged" entry is in the ALLOWED_STEPS literal.
2. test_allowed_steps_preserves_4_baseline — destruction-free (memory feedback_destruction_free_organization): the 4 original steps remain accepted. A regression here would silently zero out 4 weeks of Wave 49 G1 baseline data.
3. test_validator_still_rejects_unknown_steps — the gate must still call ALLOWED_STEPS.has(b.step). Without this assertion a future refactor could accept arbitrary strings without test failure, polluting the R2 funnel jsonl.
4. test_allowed_steps_has_exactly_5_entries — pins cardinality so a future 6th step (e.g. embedded SDK widget) is added deliberately with downstream aggregator awareness.

Verify

============================== 18 passed in 1.12s ==============================
tests/test_rum_beacon_calc_engaged.py::test_allowed_steps_now_includes_calc_engaged PASSED
tests/test_rum_beacon_calc_engaged.py::test_allowed_steps_preserves_4_baseline PASSED
tests/test_rum_beacon_calc_engaged.py::test_validator_still_rejects_unknown_steps PASSED
tests/test_rum_beacon_calc_engaged.py::test_allowed_steps_has_exactly_5_entries PASSED
(+ 8 in test_cf_pages_rum_beacon.py — 4-baseline structural)
(+ 4 in test_calc_rum_wire.py — calc client wire structural)

All 4 new + 8 baseline + 4 calc-wire = 18 PASS with the additive change in place.

Impact

• 5-stage funnel: calc_engaged now reaches R2 + CF Analytics (previously dropped at 400). Downstream scripts/ops/rum_aggregator.py will start rolling up the 5th step on the next daily aggregation pass.
• Server-side gate remains load-bearing: unknown step names still 400.
• Wave 49 G1 acceptance target — 10 unique session_ids/day × 3 days — is now measurable at the 5-stage cohort granularity, completing the measurement layer.

Constraints honored

• No rm/mv (memory feedback_destruction_free_organization).
• No main worktree (memory feedback_dual_cli_lane_atomic).
• No tier SKU / no SaaS UI (this is a measurement-only change).
• No LLM API import (this is a CF Pages Function in TypeScript).
• Brand: no legacy autonomath / zeimu-kaikei.ai strings touched.
• TypeScript validity: ALLOWED_STEPS is still new Set<string>, the validator still returns the same boolean, and no other line in the file is changed.

Files

• functions/api/rum_beacon.ts (+1 line, additive)
• tests/test_rum_beacon_calc_engaged.py (new, ~120 LOC)
• docs/research/wave49/STATE_w49_allowed_steps_ext_pr.md (this doc)