refactor(samples): lay the cobra effect out left-to-right

Move Farmed cobras to the left so the story reads in order (farm engine
-> release bridge -> wild -> cull) and the release bridge no longer
doubles back across the canvas. Positions only; dynamics unchanged.

src/model/samples.ts

@@ -21,27 +21,31 @@
  *   6. Predator and prey — two coupled Stocks whose interlocking loops oscillate.
  *   7. Epidemic          — a chain of Stocks joined by Stock→Stock Flows: no clouds.
  *
- * Last, four of Donella Meadows' system *traps* — structures that reliably misbehave
+ * Last, five of Donella Meadows' system *traps* — structures that reliably misbehave
  * (Thinking in Systems, ch. 5), to contrast the healthy dynamics above — and, paired
  * with the first, the cure that escapes it:
  *
- *   8. Tragedy of the commons   — two Reinforcing herds overgraze a *renewable* shared
+ *   8. Tragedy of the commons    — two Reinforcing herds overgraze a *renewable* shared
- *                                 Stock to bare dirt, then starve with it: all ruined.
+ *                                  Stock to bare dirt, then starve with it: all ruined.
- *   9. …commons, fixed          — the same renewable commons, but stocking is regulated
+ *   9. …commons, fixed           — the same renewable commons, but stocking is regulated
- *                                 against an agreed reserve: it holds, and the herds end
+ *                                  against an agreed reserve: it holds, and the herds end
- *                                 *larger* than the trap's boom leaves alive.
+ *                                  *larger* than the trap's boom leaves alive.
- *  10. Escalation               — a single Reinforcing loop spanning two Stocks, with
+ *  10. Escalation                — a single Reinforcing loop spanning two Stocks, with
- *                                 no brake in the structure: an arms race.
+ *                                  no brake in the structure: an arms race.
- *  11. Fixes that fail          — a fix drains the symptom Stock (B) while its side
+ *  11. Success to the successful — two equal rivals split one conserved prize (the field's
- *                                 effect refills it (R): the cure feeds the disease.
+ *                                  attention); a gap-driven Flow tilts it to whoever leads,
- *  12. Drift to low performance — a goal that erodes toward actual performance, so the
+ *                                  so a 51–49 near-tie locks in to ~100–0. Escalation's
- *                                 effort it drives never overcomes a steady decay: a
+ *                                  zero-sum twin — it concentrates instead of exploding.
- *                                 Reinforcing loop ratchets both downward.
+ *  12. Fixes that fail           — a fix drains the symptom Stock (B) while its side
+ *                                  effect refills it (R): the cure feeds the disease.
+ *  13. Drift to low performance  — a goal that erodes toward actual performance, so the
+ *                                  effort it drives never overcomes a steady decay: a
+ *                                  Reinforcing loop ratchets both downward.
  *
  * Next, the dynamic the book is named for, and the one the gallery has saved until a
  * reader knows every piece it needs:
  *
- *  13. Overshoot and collapse   — a Reinforcing harvester on a *renewable* Resource with
+ *  14. Overshoot and collapse   — a Reinforcing harvester on a *renewable* Resource with
  *                                 an extinction threshold (an Allee floor): a fleet
  *                                 overshoots the renewal rate and pushes the fishery past
  *                                 the point of no return. The dark twin of "Limits to
@@ -50,14 +54,14 @@
  * Last, the language pointed at a live debate — a classic trap (Shifting the burden to
  * the intervenor, ch. 5) wearing today's clothes:
  *
- *  14. AI deskilling spiral     — handing the burden of code quality to AI atrophies the
+ *  15. AI deskilling spiral     — handing the burden of code quality to AI atrophies the
  *                                 Expertise that holds quality up, so the team leans on AI
  *                                 harder and Technical debt spirals: addiction, not a fix.
  *
  * And a mechanical coda — the gallery's one *hard* ceiling, to contrast the emergent
  * ones (above all "Limits to growth"):
  *
- *  15. Bathtub with an overflow — the tap runs flat out (a Constant inflow that never
+ *  16. Bathtub with an overflow — the tap runs flat out (a Constant inflow that never
  *                                 reads the level) and a spillway carries whatever rises
  *                                 past the brim into a second Stock, the floor. The only
  *                                 model on the `overflow` rule — a one-sided Gap, the
@@ -67,7 +71,7 @@
  * Then one last trap, held back until the overflow rule existed to carry it — the
  * language pointed at the most-told cautionary tale in systems thinking:
  *
- *  16. The cobra effect         — a bounty on dead cobras (a Balancing fix) quietly funds a
+ *  17. The cobra effect         — a bounty on dead cobras (a Balancing fix) quietly funds a
  *                                 cobra *farm* (a Reinforcing engine); breeding outruns what
  *                                 the bounty can absorb, the farm gluts, and its now-worthless
  *                                 surplus spills through an `overflow` gate into the wild —
@@ -77,7 +81,7 @@
  *
  * And the capstone — every piece at once, at the scale the whole gallery points toward:
  *
- *  17. World on a warming planet — the Club of Rome's World3 (Meadows et al., *The Limits
+ *  18. World on a warming planet — the Club of Rome's World3 (Meadows et al., *The Limits
  *                                 to Growth*) in miniature, its pollution sector reframed
  *                                 as a climate channel: four coupled Stocks where two
  *                                 Reinforcing engines (capital, population) overshoot a
@@ -943,6 +947,82 @@ function escalation(): Model {
   )
 }
 
+/**
+ * Success to the successful — Donella Meadows' competitive-exclusion trap (Thinking
+ * in Systems, ch. 5), known in the sociology of science as the *Matthew effect*
+ * (Robert Merton, after Matthew 25:29: "unto every one that hath shall be given").
+ * Two researchers of equal ability compete for one finite thing — the field's
+ * attention — and the only difference between them is that A begins a single point
+ * ahead (Renown 51 vs 49 of a fixed 100).
+ *
+ * The community's attention is a *conserved* budget: a citation, an invitation, a
+ * grant that goes to one does not go to the other, so Renown A + Renown B never
+ * leaves 100. The marginal piece of it drifts to whoever is already better known —
+ * `attention = factor × (Renown A − Renown B)`, a single Stock→Stock Flow draining
+ * the lesser name into the greater. There are no clouds: nothing enters or leaves
+ * the system, it only *redistributes*. That one valve carries *two* Reinforcing
+ * loops — Renown A → [+] → attention → (fills A) → Renown A (more renown wins more
+ * attention), and Renown B → [−] → attention → (drains B) → Renown B (the falling
+ * name is forgotten ever faster). Neither loop has a surviving `−`, so both are
+ * Reinforcing: nothing brakes the gap, and it can only widen.
+ *
+ * A tie is therefore an *unstable* equilibrium — the knife-edge this trap balances
+ * on. A's one-point lead is enough: attention tilts to A, the gap grows, attention
+ * tilts harder, and the field locks in. Renown A climbs 51 → 100 and Renown B fades
+ * 49 → 0 by t≈42 — a near-total monopoly of acclaim, though the two were equally
+ * able. The cruel lesson Meadows draws: where the prize for winning is more power to
+ * win, it is *initial conditions*, not merit, that decide the outcome.
+ *
+ * Contrast "Escalation", the gallery's other two-Stock all-Reinforcing trap: there
+ * the cross-loop has no minus and *both* arsenals blow up together (positive-sum,
+ * unbounded); here the single loop is zero-sum — A rises only as fast as B is drained
+ * — so the same Reinforcing structure *concentrates* instead of exploding. (The cure
+ * Meadows prescribes is to break the coupling — level the field, diversify the prize,
+ * or handicap the leader — none of which the structure here contains: that is the trap.)
+ */
+function successToTheSuccessful(): Model {
+  // Two Stocks on one line, the lone attention valve nudged above their midpoint so
+  // the pipe (Renown B → attention → Renown A) and the two info links (each Stock
+  // into the valve) read apart instead of overlapping. Hand-placed, not at midpoint.
+  const renownB = makeStock({ x: -260, y: 80 }, "Renown B")
+  renownB.initialValue = 49
+  renownB.description =
+    "Researcher B's standing — equal in ability to A, and a single point behind at the start. The lesser name the attention drains away from, fading to nothing though B never did anything wrong."
+  const renownA = makeStock({ x: 260, y: 80 }, "Renown A")
+  renownA.initialValue = 51
+  renownA.description =
+    "Researcher A's standing — one point ahead at the start, and that hair's lead is all it takes. Attention concentrates here until A holds nearly the whole field's acclaim."
+  // attention = factor × (Renown A − Renown B): a Gap whose `+` level is A and `−`
+  // target is B. Source B, target A, so a positive rate drains the lesser name into
+  // the greater — and since draining B only widens the gap, the rate never reverses.
+  const attention = makeFlow({ x: 0, y: -120 }, "attention", renownB.id, renownA.id)
+  attention.rule = { kind: "gap", factor: 0.05 }
+  attention.description =
+    "The field's finite attention drifting to the better-known name, ∝ the lead (Renown A − Renown B). A conserved transfer: what A gains, B loses — the one valve through which both Reinforcing loops run."
+  return model(
+    "Success to the successful",
+    [renownB, renownA, attention],
+    [
+      link(
+        renownA,
+        attention,
+        "+",
+        "Renown A is the level in the gap: the further ahead A is, the faster attention flows its way. With the inflow it fills, this closes A's Reinforcing loop — the rich getting richer.",
+      ),
+      link(
+        renownB,
+        attention,
+        "-",
+        "Renown B is the target the gap is measured against (the − input). As B fades the gap only widens, so it is drained faster still — a second Reinforcing loop, the same minus on both the link and the outflow.",
+      ),
+    ],
+    // From a 51–49 near-tie the gap runs away: Renown A climbs 51 → ~100 and Renown B
+    // fades 49 → ~0 by t≈42, then both hold — a near-total monopoly of acclaim won on a
+    // one-point head start. The unstable 50–50 knife-edge a hair's difference tips.
+    { start: 0, stop: 50, dt: 1 },
+  )
+}
+
 /**
  * Fixes that fail — the archetype where a quick fix relieves a symptom but feeds it
  * through a side effect, so the symptom returns and the fix is reapplied for ever.
@@ -1485,23 +1565,23 @@ function bathtubOverflow(): Model {
  * is a Stock the reward built, the brake is the overflow gate, and the damage is permanent.
  */
 function cobraEffect(): Model {
-  // The policy lever (bounty) sits up top, centre, wired into three flows at once: the
+  // Laid out left→right: the farm engine on the left (a Source breeds Farmed cobras,
-  // intended cull of Wild cobras on the left, and on the right the farm's breeding and
+  // harvest draining up to a Sink), the release bridge in the centre spilling the glut
-  // cash-out. The release bridge dips below, carrying the farm's glut back across to the
+  // rightward into Wild cobras, and the bounty-driven cull running off to the right. The
-  // wild, with glut hanging beneath it. Valves are hand-placed, not at midpoints, so
+  // policy lever (bounty) sits up top, wired down into all three flows — cull, breeding,
-  // every Information Link lands in open space.
+  // cash-out — with glut beneath the bridge it gates. Hand-placed valves keep links clear.
-  const bounty = makeConverter({ x: 0, y: -300 }, "bounty")
+  const bounty = makeConverter({ x: -80, y: -340 }, "bounty")
   bounty.rule = { kind: "constant", value: 1 }
   bounty.description =
     "The reward paid per dead cobra — held at 1, a normalised policy lever, so every rate here scales with it (a bigger bounty would only run the whole story faster). One lever wired into three flows: the cull, the breeding, and the cash-out."
 
   // The intended fix: a bounty-driven cull empties the streets of wild cobras.
-  const wild = makeStock({ x: -360, y: -40 }, "Wild cobras")
+  const wild = makeStock({ x: 380, y: -40 }, "Wild cobras")
   wild.initialValue = 100
   wild.description =
     "The actual problem the bounty targets — hunted down at first, then overrun once the farm's surplus is loosed on it. It has no inflow of its own, so any rebound can only be the farm's doing."
-  const cullSink = makeCloud({ x: -680, y: -40 })
+  const cullSink = makeCloud({ x: 920, y: -40 })
-  const culling = makeFlow({ x: -520, y: -40 }, "culling", wild.id, cullSink.id)
+  const culling = makeFlow({ x: 660, y: -40 }, "culling", wild.id, cullSink.id)
   // culling = 0.16 × Wild × bounty: the Balancing drain, ∝ the stock. Fast enough to
   // crash the wild population by t≈20 — the policy's whole visible success.
   culling.rule = { kind: "proportional", factor: 0.16 }
@@ -1509,19 +1589,19 @@ function cobraEffect(): Model {
     "Wild cobras killed for the bounty, ∝ Wild cobras × bounty — the intended Balancing fix that empties the streets at first."
 
   // The perverse stock: a farm bred to cash in on the bounty.
-  const farm = makeStock({ x: 360, y: -40 }, "Farmed cobras")
+  const farm = makeStock({ x: -520, y: -40 }, "Farmed cobras")
   farm.initialValue = 5
   farm.description =
     "Cobras bred to cash in on the bounty — the Stock the reward calls into being. It compounds unseen while the streets look clear, then spills its surplus into the wild."
-  const breedSrc = makeCloud({ x: 680, y: -40 })
+  const breedSrc = makeCloud({ x: -980, y: -200 })
-  const breeding = makeFlow({ x: 520, y: -40 }, "breeding", breedSrc.id, farm.id)
+  const breeding = makeFlow({ x: -760, y: -200 }, "breeding", breedSrc.id, farm.id)
   // breeding = 0.31 × Farm × bounty: Farm → breeding → Farm, no `−` → the Reinforcing
   // engine the bounty funds without meaning to.
   breeding.rule = { kind: "proportional", factor: 0.31 }
   breeding.description =
     "The farm breeding more cobras, ∝ Farmed cobras × bounty — the Reinforcing engine the bounty funds without intending to: more breeding stock, more bred."
-  const harvestSink = makeCloud({ x: 360, y: -260 })
+  const harvestSink = makeCloud({ x: 600, y: -220 })
-  const harvest = makeFlow({ x: 360, y: -140 }, "harvest", farm.id, harvestSink.id)
+  const harvest = makeFlow({ x: 400, y: -220 }, "harvest", farm.id, harvestSink.id)
   // harvest = 0.10 × Farm × bounty: farmed cobras killed and turned in — the rule beating,
   // and a Balancing drain on the farm.
   harvest.rule = { kind: "proportional", factor: 0.1 }
@@ -1531,11 +1611,11 @@ function cobraEffect(): Model {
   // The backfire bridge: once the farm gluts, its worthless surplus is dumped into the
   // wild. A one-sided overflow gate (shut below the glut) — no scripted policy reversal
   // needed; the release falls out of the farm outgrowing its own worth.
-  const glut = makeConverter({ x: 0, y: 300 }, "glut")
+  const glut = makeConverter({ x: -260, y: 260 }, "glut")
   glut.rule = { kind: "constant", value: 200 }
   glut.description =
     "The farm size past which cobras lose their worth (a fixed 200) — the threshold the spill opens above. A structural stand-in for the day the bounty was scrapped and the snakes became worthless."
-  const releases = makeFlow({ x: 0, y: 120 }, "releases", farm.id, wild.id)
+  const releases = makeFlow({ x: -40, y: 60 }, "releases", farm.id, wild.id)
   // releases = max(0, 0.6 × (Farm − glut)): shut while the farm is worth keeping, then it
   // carries off the surplus. The overflow that overruns the wild — and, draining the farm
   // above the glut, the Balancing brake that caps it.
@@ -1908,6 +1988,12 @@ export const SAMPLES: Sample[] = [
     blurb: "An arms race: one Reinforcing loop spanning two Stocks.",
     build: escalation,
   },
+  {
+    title: "Success to the successful",
+    blurb:
+      "Two equal researchers, one a hair ahead: the field's attention locks onto the leader and the rival fades — a winner-take-all trap.",
+    build: successToTheSuccessful,
+  },
   {
     title: "Fixes that fail",
     blurb: "Road building eases congestion (B) but induces the traffic that refills it (R).",