PROCITY/docs/RETRO_V4.md

# PROCITY v4 — THE REAL MAP: the epoch retro

*Fable (integrator), 2026-07-16, written after the `v4.0` tag (`8ac3b18`) per ROUND22 ledger #6.
Epoch span: the R17 scout → R22 close (charter: [V4_REAL_MAP.md](V4_REAL_MAP.md)). Tags:
`v4.0-alpha` → `v4.0-beta` → `v4.0`.*

## The epoch in numbers

**23 real Australian towns · 1,210 real shops (298 secondhand heroes) · all 8 states and
territories · on their actual streets.** Selfcheck grew 15,277 → **161,300** checks. 36 town
goldens pinned in one commit. Every real graph lands as **1 connected component** with 3 venues.
The covenant was never broken: `?classic=1` boots the exact v2 town, `0x3fa36874`, byte-identical
through six rounds of the largest structural change in the project's history. The default
synthetic town is untouched. One sanctioned golden move per round, every one recorded.

## What shipped, in one breath

Cache schema v2 → the real-graph lift (junction-protected Douglas–Peucker, cull/bridge
connectivity) → the density widening under John's SUBTLE directive (heroes never subsampled,
texture capped at 3×, and D proved the heroes *gained* footfall) → cluster-adjacent venues (11/15
were stranded; 0/15 after) → the tram's shop-adjacency ruling with per-town fencing → the town
selector → the poster cap → the furniture tri diet → the five-frame release tour, including one
honestly-dead town. Plus the marriage: **Lane G** (ultra) joined mid-epoch, merged at a round
boundary, with the depot format ruled (no-Draco) and the G2a atlas contract reviewed.

## What worked — keep doing these

1. **Measurement over brief.** The epoch's defining pattern. A proved my poster "nudge" was
   geometrically impossible and fixed the root cause. D refuted my prescribed `_rotWithHips`
   with an in-shell proof. B tested a five-round-old park reason and found it was folklore.
   D published a self-correction of its own headline metric. F recorded a re-measure that got
   *worse*, and refused to caption a dead town as proof the floor holds. The brief is a
   hypothesis; the lane's measurement is the ruling.
2. **The measure-first fix loop.** R22's blocking gate ran F measured → B diagnosed (91.5%
   attribution by hide-a-layer) → A confirmed not-A with numbers → E owned it and fixed (−51%)
   → F re-measured. Four lanes, one gate, zero ego, one round.
3. **Alpha as failure-list.** R18's brief said the deliverable was the failure list, and it was:
   fragmentation (105 components), the BIG_CITY misfire, the DP junction-drop — each surfaced by
   audit, filed with measurements, fixed the next round. Budget the discovery round; don't ask
   it to also be the fix round.
4. **Contract-first beats sequencing.** R16's order inverted (lanes ran before F's flip) and
   nothing broke, because contracts were published in the brief. Same for schema v2, C's mapping
   table, the backline shape, the G2a atlas contract. The half-day-handshake rule is the
   project's real synchronization primitive.
5. **Drops are counted, never silent.** `norm.dropped` by cause, `textureDropped`, fenced towns
   named, the 6.4% seating tail per-cause-attributed. Nothing in the pack pretends.
6. **Independent convergence.** The thin-tail finding was discovered twice in one round by
   different methods (F's tour frame; D's nearest-neighbour spacing metric) — that's the
   redundancy of honest lanes, and it's why the finding is trustworthy.

## What cost us — fix these

1. **Lane F is the fragile point.** F no-showed R14 and R18, and stalled mid-gate in R21. Every
   time, the epoch sat untagged with five lanes done. The close is the longest, most serial
   brief and it runs last, when sessions die. *Mitigation adopted going forward: F's brief is
   written in resumable numbered items (R21 proved a successor can pick up mid-gate), and the
   integrator checks for uncommitted F WIP before declaring a round done.*
2. **Soft ceilings invite drift.** `venue_night` breached the 200k "soft" reference twice
   (+0.5%, then +11%) before R22 made it blocking. *Rule going forward: a stress view that
   breaches twice is automatically a blocking gate the next round.*
3. **Old assets bite in new contexts.** The tri-diet driver was four furniture GLBs sized in
   R6 for a 22-edge synthetic town, harmless for sixteen rounds until a 966-edge real graph
   multiplied their cadence. *When the context scales, re-audit the assets it multiplies.*
4. **The integrator was wrong twice** (the nudge, `_rotWithHips`). Acceptable — that's what
   measurement-over-brief is for — but both were cases of prescribing the mechanism instead of
   the outcome. *Briefs should state acceptance; lanes own method.*

## The v4.x ledger (carried, measured, not hidden)

- **The thin-tail clustering floor** (the epoch's parting finding): aliveness is not shop
  *count* but **clustering** — median nearest-neighbour spacing (darwin 27 m ALIVE vs toowoomba
  388 m DEAD at the same 12 shops). Candidate law: E curates on spacing, `validateTownCache`
  warns above a threshold; toowoomba gets re-bboxed or retired.
- The **6.4% seating tail** (daylesford 19%, fitzroy 13%) — known, per-cause, the drop-and-count
  ruling stands.
- `GIG_RANGE` chunk-neighbour lookup (D, 8.7% blind) · instrument `_lo` LOD · tram-stop close-ped
  tri diet · drummer pelvic-lean v2 · awning fabric ripple · flag retirement (classic keeps
  soaking) · selector polish beyond debug-grade.

## The next epoch — Fable's recommendation to John

Three chartered candidates remain: **the GODVERSE economy (G2/G3)**, **the editor/override
layer**, **multiplayer presence**.

**Recommendation: v5 = THE REAL SHOP — the GODVERSE economy.** The argument: v4 made the towns
real; v5 makes the *shops* real. The marriage lane is already live (G2a contract reviewed, first
atlases next), dealgod holds 1.77M real items with photos, and the destination — walk Fitzroy's
real street into a real op shop, riffle a real crate, and the record you buy is one-of-a-kind
because it's real stock (sold means GONE) — is the most PROCITY-shaped thing either studio can
build. Sequence per the standing ruling: **G3 design doc first** (both integrators + John;
the server enriches, never gates — full offline play is non-negotiable), G2a atlases land
meanwhile, v4.x tail runs as a light parallel lane. The editor and multiplayer stay chartered
for v6+ — the editor gets stronger the more real content exists to override, and presence gets
stronger the more there is to visit.

*— Fable. Twenty-two rounds: seed → town → weather → crowd → interiors → stock → gigs → the flip
→ real roads → real shops → real Australia. The covenant held the whole way.*