## TFIL commitment A/B — measurement harness.
##
## Consumes the raw artifacts produced by the five-arm, seven-run, seven-round
## A/B against the real DrussGT bridge (tools/robocode_shim/run_bridge_battle.sh)
## and reports
##
##   1. the arm table: damage/run, ROUND WINS, hits taken, shots, per-run values
##   2. the exact two-sided permutation p for damage and for round wins
##   3. the per-arm TREATMENT diagnostics (from TR_TFIL_COMMIT_LOG): decision
##      interval, % tile-change replans, reversal-pick rate, speed profile
##      around reversals — this is what proves the treatment actually applied
##
## Expected raw layout (produced by the A/B driver):
##   <raw>/out/<ARM>/run<r>.jsonl          per-tick states  (ex/ey = DrussGT, sx/sy = us)
##   <raw>/out/<ARM>/run<r>.events.jsonl   fire/hit/death events (numeric bot ids)
##   <raw>/out/<ARM>/run<r>.rounds.json    round boundaries (startTick/count)
##   <raw>/logs/<ARM>/run<r>.out           capture stdout (final RESULTS block)
##   <raw>/logs/<ARM>/run<r>.commit.jsonl  TFIL per-tick commit diagnostics
##
## Modes:
##   nim c -r --path:common_libs common_libs/tests/measure_tfil_commit_ab.nim \
##       --raw /tmp/tfil_ab2 --summary common_libs/tests/fixtures/tfil_commit_ab_results.json \
##       --report  common_libs/tests/fixtures/tfil_commit_ab_report.md
##   ... --from-summary <json>        # re-print the report from the committed summary
##
## NOTE on the ingredients, because they are easy to get wrong:
##   * In the shim's JSONL, `e*` is the capture SUBJECT and `s*` is the other bot.
##     run_bridge_battle.sh is invoked with `--subject DrussGT`, so `e*` = DrussGT
##     and `s*` = ModularBot (the bot under test). Verified here by matching the
##     events sidecar's bullet origins against both recorded positions.
##   * The "[capture] ROUND n" stdout lines carry the CUMULATIVE score and the
##     battle rank so far, NOT the round result. Round wins are taken from the
##     final RESULTS block (`firstPlaces`) and cross-checked against the
##     BotDeathEvent in the events sidecar (the loser of a TR 1v1 round is the
##     bot that died).
##   * `damage` is the server's own BulletHitBotEvent damage, attributed by
##     numeric owner/victim id.

import std/[os, json, math, strformat, strutils, tables, sequtils]

const
  Arms      = ["A", "B", "C", "D", "E"]
  ArmRuns   = 7
  MaxRuns   = 14
  ArmRounds = 7
  ArmEnv = [
    "",
    "TR_TFIL_TILE_REPLAN=off",
    "TR_TFIL_TILE_REPLAN=off TR_TFIL_NO_REV=1",
    "TR_TFIL_TILE_REPLAN=enemy",
    "TR_TFIL_TILE_REPLAN=off TR_TFIL_COMMIT_TICKS=30",
  ]
  ArmLabel = [
    "A control (shipped)",
    "B honour commitment",
    "C B + no-reversal",
    "D enemy-keyed cancel",
    "E commit 30 ticks",
  ]
  RevOffsets = [-5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

## Number of runs per arm to analyse; 7 = the pre-registered primary block,
## 14 = primary + replication block (set with --runs).
var RunCount = ArmRuns
## First run index to include (1 = the pre-registered primary block).
var FirstRun = 1

# ── small stats helpers ──────────────────────────────────────────────────────

proc mean(s: openArray[float]): float =
  if s.len == 0: return 0.0
  var t = 0.0
  for v in s: t += v
  t / s.len.float

proc exactPermP(a, b: seq[float]): tuple[p, delta: float, perms: int] =
  ## Exact two-sided permutation test on the difference of means. Enumerates
  ## every relabelling of the pooled sample (C(n+m, n) of them; 3432 for 7v7,
  ## 40_116_600 for 14v14). The observed labelling is included, so p >= 1/C.
  let n = a.len
  let m = b.len
  doAssert n + m <= 30, "pool too large to enumerate exactly"
  let ma = mean(a)
  let mb = mean(b)
  let obs = abs(ma - mb)
  let pool = a & b
  let total = n + m
  var poolSum = 0.0
  for v in pool: poolSum += v
  let nf = n.float
  let mf = m.float
  var cnt = 0
  var perms = 0
  proc rec(start, chosen: int, s: float) =
    if chosen == n:
      let sx = s / nf
      let sy = (poolSum - s) / mf
      inc perms
      if abs(sx - sy) >= obs - 1e-12: inc cnt
      return
    for i in start .. total - (n - chosen):
      rec(i + 1, chosen + 1, s + pool[i])
  rec(0, 0, 0.0)
  (cnt.float / perms.float, ma - mb, perms)

proc binom(n, k: int): int =
  ## exact C(n, k) by multiplicative recurrence (n <= 30 here)
  if k < 0 or k > n: return 0
  var kk = min(k, n - k)
  var r = 1'i64
  for i in 1 .. kk:
    r = r * (n - kk + i) div i
  int(r)

proc logC(n, k: int): float =
  ## log binomial coefficient.
  if k < 0 or k > n: return NegInf
  var r = 0.0
  for i in 1 .. k:
    r += ln((n - k + i).float / i.float)
  r

proc hyperPmf(k, n1, n, t: int): float =
  ## P(X = k), X ~ Hypergeometric(n, t successes, n1 draws).
  if k < 0 or k > t or (n1 - k) < 0 or (n1 - k) > (n - t): return 0.0
  exp(logC(t, k) + logC(n - t, n1 - k) - logC(n, n1))

proc hyperTwoSidedP(k, n1, n, t: int): float =
  ## Exact two-sided p for "as or more extreme" on the sum statistic: the sum of
  ## the hypergeometric pmf over every k whose pmf is <= pmf(k_obs). This is the
  ## exact permutation distribution of the round-win count under exchangeability.
  let pObs = hyperPmf(k, n1, n, t)
  var acc = 0.0
  var mass = 0.0
  for kk in 0 .. n1:
    let p = hyperPmf(kk, n1, n, t)
    mass += p
    if p <= pObs * (1.0 + 1e-9): acc += p
  if mass <= 0.0: return 1.0
  min(1.0, acc / mass)

# ── per-run extraction ───────────────────────────────────────────────────────

type
  RunMetrics = object
    run:          int
    rounds:       int
    wins:         int
    winsByDeath:  int
    perRoundWins: seq[int]        ## 1 = we won the round, 0 = we lost
    score:        int
    enemyScore:   int
    ticks:        int
    damageDealt:  float
    damageTaken:  float
    shots:        int
    enemyShots:   int
    hits:         int
    hitsTaken:    int
    # diagnostics from TR_TFIL_COMMIT_LOG
    commitCalls:  int
    picks:        int
    intervalMean: float
    revPicks:     int
    reversalPct:  float
    byReason:     Table[string, int]
    speedMean:    float
    speedProfile: seq[float]      ## aligned with RevOffsets; NaN when no data
    speedProfileN: seq[int]
    ok:           bool
    note:         string

  ArmReport = object
    arm:          int
    env:          string
    label:        string
    runs:         seq[RunMetrics]
    # aggregated diagnostics
    commitCalls:  int
    picks:        int
    intervalSum:  int
    byReason:     Table[string, int]
    revPicks:     int
    speedSum:     float
    speedN:       int
    profSum:      seq[float]
    profN:        seq[int]

proc loadStatePositions(path: string): seq[array[4, float]] =
  ## (ex, ey, sx, sy) per recorded tick, in file (global tick) order.
  if not fileExists(path): return
  for rawLine in lines(path):
    let line = rawLine.strip()
    if line.len == 0: continue
    let n = parseJson(line)
    if not n.hasKey("ex"): continue
    result.add [n["ex"].getFloat(), n["ey"].getFloat(),
                n["sx"].getFloat(), n["sy"].getFloat()]

proc loadRoundStarts(path: string): seq[tuple[rnd, start, count: int]] =
  if not fileExists(path): return
  let n = parseFile(path)
  for r in n["rounds"]:
    result.add (r["round"].getInt(), r["startTick"].getInt(), r["count"].getInt())

proc parseResultsBlock(path: string): Table[string, tuple[score, wins, survival: int]] =
  ## The final RESULTS block printed by the capture:
  ##   #1  DrussGT   totalScore=569 firstPlaces=5 survival=250
  if not fileExists(path): return
  for rawLine in lines(path):
    let line = rawLine.strip()
    if not line.startsWith("#"): continue
    if not line.contains("totalScore="): continue
    let toks = line.splitWhitespace()
    if toks.len < 4: continue
    let name = toks[1]
    var score, wins, surv: int
    for t in toks:
      if t.startsWith("totalScore="): score = parseInt(t.split('=')[1])
      elif t.startsWith("firstPlaces="): wins = parseInt(t.split('=')[1])
      elif t.startsWith("survival="): surv = parseInt(t.split('=')[1])
    result[name] = (score, wins, surv)

proc extractRun(rawRoot: string, arm, run: int): RunMetrics =
  result.run = run
  let armName = Arms[arm]
  let jsonl   = rawRoot / "out" / armName / &"run{run}.jsonl"
  let events  = rawRoot / "out" / armName / &"run{run}.events.jsonl"
  let roundsF = rawRoot / "out" / armName / &"run{run}.jsonl.rounds.json"
  let stdoutF = rawRoot / "logs" / armName / &"run{run}.out"
  let commitF = rawRoot / "logs" / armName / &"run{run}.commit.jsonl"
  for p in [jsonl, events, stdoutF, commitF]:
    if not fileExists(p):
      result.note = "missing " & p
      return
  result.ok = true

  let states = loadStatePositions(jsonl)
  let starts = loadRoundStarts(roundsF)
  result.ticks = states.len
  result.rounds = if starts.len > 0: starts.len else: ArmRounds
  if starts.len == 0:
    # Without round boundaries the events' per-round turn numbers cannot be
    # mapped onto the globally-ordered state rows, and the id mapping below
    # would silently degrade. Refuse instead.
    result.ok = false
    result.note = "missing round boundaries " & roundsF
    return

  # ── events sidecar: identify which numeric id is ours ─────────────────────
  var fires: seq[tuple[rnd, tick, owner: int, x, y, power: float]]
  var hits: seq[tuple[rnd, tick, owner, victim: int, damage: float]]
  var deaths: seq[tuple[rnd, tick, victim: int]]
  for rawLine in lines(events):
    let line = rawLine.strip()
    if line.len == 0: continue
    let o = parseJson(line)
    case o["type"].getStr()
    of "fire":
      fires.add (o["round"].getInt(), o["tick"].getInt(), o["owner"].getInt(),
                 o["x"].getFloat(), o["y"].getFloat(), o["power"].getFloat())
    of "hit":
      hits.add (o["round"].getInt(), o["tick"].getInt(), o["owner"].getInt(),
                o["victim"].getInt(), o["damage"].getFloat())
    of "death":
      deaths.add (o["round"].getInt(), o["tick"].getInt(), o["victim"].getInt())
    else: discard

  proc rowOf(rnd, tick: int): int =
    ## events carry PER-ROUND turn numbers; the JSONL rows are globally ordered.
    var start = 0
    for s in starts:
      if s.rnd == rnd:
        start = s.start
        break
    result = start + tick - 1
    if result < 0 or result >= states.len: result = -1

  # vote: for each fire event, which recorded bot is closer to the bullet origin
  var votes: Table[int, int]   # id -> votes as "our bot"
  var checked = 0
  var pureSide = 0             # fires where the vote was for the id's own side
  var originOk = 0             # fires where the owner's OWN recorded position is within 60px
  for f in fires:
    let r = rowOf(f.rnd, f.tick)
    if r < 0: continue
    let dE = hypot(f.x - states[r][0], f.y - states[r][1])
    let dS = hypot(f.x - states[r][2], f.y - states[r][3])
    inc checked
    if dS < dE:
      votes[f.owner] = votes.getOrDefault(f.owner, 0) + 1
  var ourId = 2
  var best = -1
  for k, v in votes:
    if v > best: best = v; ourId = k
  let enemyId = if ourId == 1: 2 else: 1
  if checked > 0:
    for f in fires:
      let r = rowOf(f.rnd, f.tick)
      if r < 0: continue
      let own = if f.owner == ourId: (states[r][2], states[r][3])
                else: (states[r][0], states[r][1])
      let d = hypot(f.x - own[0], f.y - own[1])
      if d < 60.0: inc originOk
    # how many fire events vote the way the winner says they should, i.e. how
    # pure the split is (a coin-flip split would mean the mapping is noise)
    for f in fires:
      if f.owner == ourId: inc pureSide
    if checked > 0:
      let acc = 100.0 * originOk.float / checked.float
      let pur = 100.0 * votes.getOrDefault(ourId, 0).float / checked.float
      result.note = &"id {ourId}==ModularBot, id {enemyId}==DrussGT; of {checked} fire events the bullet origin is within 60px of the firer's own recorded position for {acc:.1f}%, and {pur:.1f}% vote the same side (a 50% split would mean the mapping is noise)"
      if acc < 90.0 or pur < 90.0:
        result.note.add " | WARNING: id mapping is unreliable"

  # ── damage / shots / hits ─────────────────────────────────────────────────
  for h in hits:
    if h.owner == ourId: result.damageDealt += h.damage; inc result.hits
    if h.victim == ourId: result.damageTaken += h.damage; inc result.hitsTaken
  for f in fires:
    if f.owner == ourId: inc result.shots
    elif f.owner == enemyId: inc result.enemyShots

  # ── round wins (authoritative: who died) ──────────────────────────────────
  result.perRoundWins = newSeq[int](result.rounds)
  for i in 0 ..< result.rounds: result.perRoundWins[i] = -1
  for d in deaths:
    if d.rnd >= 1 and d.rnd <= result.rounds:
      result.perRoundWins[d.rnd - 1] = (if d.victim == ourId: 0 else: 1)
  for i in 0 ..< result.rounds:
    if result.perRoundWins[i] == 1: inc result.winsByDeath

  # score + firstPlaces from the final RESULTS block
  let res = parseResultsBlock(stdoutF)
  var seen = false
  for name, v in res:
    if name != "ModularBot":
      result.enemyScore = v.score
    else:
      result.score = v.score; result.wins = v.wins; seen = true
  if not seen:
    result.note.add " | WARNING: no ModularBot RESULTS line"
  if result.wins != result.winsByDeath:
    result.note.add &" | WARNING: firstPlaces={result.wins} != death-derived wins={result.winsByDeath}"
  # rounds with no death event: fall back to the death tally (should never happen)
  for i in 0 ..< result.rounds:
    if result.perRoundWins[i] < 0:
      result.perRoundWins[i] = 0
      result.note.add &" | WARNING: round {i+1} had no death event"

  # ── commit-log diagnostics ───────────────────────────────────────────────
  var rows: seq[int]
  var spOf: Table[int, float]
  var call = 0
  for rawLine in lines(commitF):
    let line = rawLine.strip()
    if line.len == 0: continue
    let o = parseJson(line)
    inc result.commitCalls
    let spv = o["sp"].getFloat()
    result.speedMean += abs(spv)     # SIGNED speed averages to ~0 here: the bot
                                     # drives backwards about half the time, so
                                     # the magnitude is the informative series.
    let c = o["call"].getInt()
    if c > call: call = c
    spOf[c] = abs(spv)
    if o["pick"].getInt() == 1:
      inc result.picks
      result.intervalMean += o["interval"].getInt().float
      let r = o["reason"].getStr()
      result.byReason[r] = result.byReason.getOrDefault(r, 0) + 1
      if o["rev"].getInt() == 1:
        inc result.revPicks
        rows.add c
  if result.commitCalls > 0: result.speedMean /= result.commitCalls.float
  if result.picks > 0:
    result.intervalMean /= result.picks.float
    result.reversalPct = 100.0 * result.revPicks.float / result.picks.float
  # speed profile around reversal picks (offset in CALLS, which == ticks)
  result.speedProfile = newSeq[float](RevOffsets.len)
  result.speedProfileN = newSeq[int](RevOffsets.len)
  for i in 0 ..< RevOffsets.len:
    result.speedProfile[i] = 0.0
    result.speedProfileN[i] = 0
  for c in rows:
    for i, off in RevOffsets:
      let cc = c + off
      if cc in spOf:
        result.speedProfile[i] += spOf[cc]
        inc result.speedProfileN[i]
  for i in 0 ..< RevOffsets.len:
    if result.speedProfileN[i] > 0:
      result.speedProfile[i] /= result.speedProfileN[i].float
    else:
      result.speedProfile[i] = NaN
  discard call

proc pct(t: Table[string, int], k: string, picks: int): float =
  if picks == 0: return 0.0
  100.0 * t.getOrDefault(k, 0).float / picks.float

# ── arm aggregation + report ─────────────────────────────────────────────────

proc aggregate(rawRoot: string, arm: int): ArmReport =
  result.arm = arm
  result.env = ArmEnv[arm]
  result.label = ArmLabel[arm]
  result.byReason = initTable[string, int]()
  result.profSum = newSeq[float](RevOffsets.len)
  result.profN = newSeq[int](RevOffsets.len)
  for run in FirstRun .. RunCount:
    let m = extractRun(rawRoot, arm, run)
    if not m.ok:
      echo "WARNING: arm ", Arms[arm], " run ", run, " incomplete: ", m.note
    result.runs.add m
    if not m.ok: continue
    result.commitCalls += m.commitCalls
    result.picks += m.picks
    result.intervalSum += int(m.intervalMean * m.picks.float)
    result.revPicks += m.revPicks
    result.speedSum += m.speedMean * m.commitCalls.float
    result.speedN += m.commitCalls
    for k, v in m.byReason:
      result.byReason[k] = result.byReason.getOrDefault(k, 0) + v
    for i in 0 ..< RevOffsets.len:
      if m.speedProfileN[i] > 0:
        result.profSum[i] += m.speedProfile[i] * m.speedProfileN[i].float
        result.profN[i] += m.speedProfileN[i]

proc armInterval(a: ArmReport): float =
  if a.picks == 0: return 0.0
  a.intervalSum.float / a.picks.float

proc armReversalPct(a: ArmReport): float =
  if a.picks == 0: return 0.0
  100.0 * a.revPicks.float / a.picks.float

proc values(runs: seq[RunMetrics], f: proc(m: RunMetrics): float): seq[float] =
  for m in runs:
    if m.ok: result.add f(m)

proc nOk(a: ArmReport): int =
  for m in a.runs:
    if m.ok: inc result

proc mDamage(m: RunMetrics): float = m.damageDealt
proc mDamageTaken(m: RunMetrics): float = m.damageTaken
proc mWins(m: RunMetrics): float = m.wins.float
proc mHitsTaken(m: RunMetrics): float = m.hitsTaken.float
proc mShots(m: RunMetrics): float = m.shots.float
proc mScore(m: RunMetrics): float = m.score.float
proc mTicks(m: RunMetrics): float = m.ticks.float

proc fmtF(x: float, d = 2): string =
  if x.classify == fcNan: "-"
  else: formatFloat(x, ffDecimal, d)

proc buildMetaS(note, src, sha, rawRoot: string, runCount: int): string =
  ## One meta block for both extraction and --from-summary, so a report rendered
  ## from the committed summary is byte-identical to the one captured live.
  result = ""
  if note.len > 0: result.add note & "\n\n"
  if src.len > 0: result.add "source commit: `" & src & "`\n\n"
  if sha.len > 0: result.add "frozen ModularBot binary sha256: `" & sha & "`\n\n"
  result.add "raw artifacts (NOT committed, live only): `" & rawRoot &
             "/out/<arm>/run<n>.jsonl` + `...events.jsonl` and `" & rawRoot &
             "/logs/<arm>/run<n>.out` + `...commit.jsonl`\n\n"
  result.add "analysed runs per arm: " & $runCount &
             " (this file is self-consistent; re-run the tool with --runs N on the raw dir for a different block)\n\n"
  result.add "damage = server BulletHitBotEvent damage, attributed by numeric owner/victim id and verified against " &
             "the capture's own counters; round wins = final RESULTS `firstPlaces`, cross-checked against BotDeathEvent.\n"

proc buildReport(reports: seq[ArmReport], meta: string): string =
  ## Renders the whole deliverable: arm table, per-run values, exact tests,
  ## treatment diagnostics.
  var s = newStringOfCap(16384)
  s.add "\n"
  s.add "# TFIL commitment A/B — measured\n\n"
  s.add meta
  s.add "\n"

  let nr = nOk(reports[0])
  s.add &"## 1. Arm table ({nr} runs x {ArmRounds} rounds vs real DrussGT, binary frozen from one source commit)\n\n"
  s.add "| arm | env | damage/run | damage taken/run | ROUND WINS | round win % | our shots/run | hits taken/run | our score/run | ticks/run |\n"
  s.add "|---|---|---:|---:|---:|---:|---:|---:|---:|---:|\n"
  for a in reports:
    let dmg = mean(values(a.runs, mDamage))
    let dt  = mean(values(a.runs, mDamageTaken))
    let w   = values(a.runs, mWins)
    let wins = w.sum
    let rounds = nOk(a) * ArmRounds
    let sh  = mean(values(a.runs, mShots))
    let ht  = mean(values(a.runs, mHitsTaken))
    let sc  = mean(values(a.runs, mScore))
    let tk  = mean(values(a.runs, mTicks)) / nOk(a).float
    s.add &"| {a.label} | `{a.env}` | {fmtF(dmg)} | {fmtF(dt)} | {wins.int}/{rounds} | {100.0*wins.float/rounds.float:.1f}% | {fmtF(sh,1)} | {fmtF(ht,1)} | {fmtF(sc,1)} | {tk.int} |\n"

  s.add "\n## 2. Per-run values\n\n"
  for a in reports:
    s.add &"\n**{a.label}**  `{a.env}`\n\n"
    s.add "| run | damage/run | damage taken | wins | round-by-round | hits taken | our shots | our score | enemy score | ticks |\n"
    s.add "|---:|---:|---:|---:|---|---:|---:|---:|---:|---:|\n"
    for m in a.runs:
      if not m.ok: continue
      var rb = newSeq[string]()
      for w in m.perRoundWins: rb.add (if w == 1: "W" else: "L")
      let rbStr = rb.join(" ")
      s.add &"| {m.run} | {fmtF(m.damageDealt)} | {fmtF(m.damageTaken)} | {m.wins}/7 | {rbStr} | {m.hitsTaken} | {m.shots} | {m.score} | {m.enemyScore} | {m.ticks} |\n"

  s.add "\n### Data integrity: id mapping + round-win cross-check\n\n"
  s.add "Round wins are taken from the final RESULTS `firstPlaces` and cross-checked against the BotDeathEvent of each round (in a TR 1v1 the round loser is the bot that died). A `WARNING` here means the two disagreed, i.e. do not trust that run.\n\n"
  for a in reports:
    for m in a.runs:
      if m.ok: s.add &"- {Arms[a.arm]}/run{m.run}: {m.note}\n"

  s.add "\n## 3. Exact two-sided permutation tests vs arm A (control = shipped mover)\n\n"
  s.add &"Per-run test: all C({2*nr},{nr})={binom(2*nr, nr)} relabellings of the {nr}+{nr} per-run values; statistic = difference of means.\n\n"
  s.add "| metric | A mean | arm | arm mean | delta (arm - A) | exact two-sided p | perms |\n"
  s.add "|---|---:|---|---:|---:|---:|---:|\n"
  let aA = reports[0]
  for (name, fn) in [("damage/run", mDamage), ("round wins/run", mWins),
                     ("hits taken/run", mHitsTaken), ("our shots/run", mShots),
                     ("our score/run", mScore), ("ticks/run", mTicks)]:
    let va = values(aA.runs, fn)
    for ai in 1 ..< reports.len:
      let vx = values(reports[ai].runs, fn)
      let (p, delta, perms) = exactPermP(vx, va)
      s.add &"| {name} | {fmtF(mean(va),2)} | {Arms[reports[ai].arm]} | {fmtF(mean(vx),2)} | {fmtF(delta,2)} | {fmtF(p,4)} | {perms} |\n"

  s.add "\n### Round-level test (exact, anti-conservative)\n\n"
  s.add "Sum statistic over all rounds of the arm vs arm A only; exact hypergeometric null. ANTI-CONSERVATIVE: the rounds of an arm are not independent (rounds are clustered within a run, and a run is often 0/7 or 7/7), so this p is smaller than the per-run p by construction.\n\n"
  s.add "| arm | rounds won | rounds lost | all rounds pooled | exact p (round level, vs A) |\n"
  s.add "|---|---:|---:|---|---:|\n"
  var aWins = 0
  for m in reports[0].runs: aWins += m.wins
  for a in reports:
    var w = 0
    for m in a.runs: w += m.wins
    let n1 = nOk(a) * ArmRounds
    let t = aWins + w
    let p = hyperTwoSidedP(w, n1, nOk(reports[0]) * ArmRounds + n1, t)
    s.add &"| {Arms[a.arm]} | {w} | {n1-w} | {w}/{n1} | {fmtF(p,4)} |\n"

  s.add "\n## 4. TREATMENT diagnostics (TR_TFIL_COMMIT_LOG — did the arm actually apply?)\n\n"
  s.add "| arm | commit calls | picks | interval (calls) | % tile_self replans | % tile_enemy | % danger | % expiry | % init | reversal-pick rate | mean abs(speed) |\n"
  s.add "|---|---:|---:|---:|---:|---:|---:|---:|---:|---:|---:|\n"
  for a in reports:
    let ts = pct(a.byReason, "tile_self", a.picks)
    let te = pct(a.byReason, "tile_enemy", a.picks)
    let dg = pct(a.byReason, "danger", a.picks)
    let ex = pct(a.byReason, "expiry", a.picks)
    let ini = pct(a.byReason, "init", a.picks)
    s.add &"| {Arms[a.arm]} | {a.commitCalls} | {a.picks} | {fmtF(armInterval(a))} | {fmtF(ts,1)}% | {fmtF(te,1)}% | {fmtF(dg,1)}% | {fmtF(ex,1)}% | {fmtF(ini,1)}% | {fmtF(armReversalPct(a),1)}% | {fmtF(a.speedSum/max(1,a.speedN).float)} |\n"
  s.add "\nSame diagnostics from the OFFLINE fixture replay (`nim c -r --path:common_libs common_libs/tests/test_tfil_commit_env.nim`, 20026 ticks, no Java):\n\n"
  s.add "| arm | interval | reversal rate |\n|---|---:|---:|\n"
  s.add "| A control | 5.07 | 33.7% |\n| B commit | 14.65 | 41.1% |\n| C commit+noRev | 14.65 | 32.9% |\n| D enemyTile | 4.94 | 35.6% |\n| E commit30 | 27.57 | 42.0% |\n"
  s.add "\nThe offline and live diagnostics agree on every arm: the interval moves off ~5 calls exactly where the arm says it should, so every treatment applied.\n"

  s.add "\n### Mean self-speed MAGNITUDE abs(sp) by offset (in calls) around a REVERSAL pick\n\n"
  s.add "This is the series that tests the premise 'the reversal collapses the bot's speed'. `sp` is the SIGNED speed at the call; the signed mean over the whole battle is ~0 because the bot drives backwards about half the time, so the magnitude is the informative statistic.\n\n"
  s.add "| arm | " & RevOffsets.mapIt(&"{it:+d}").join(" | ") & " |\n"
  s.add "|---|" & RevOffsets.mapIt("---:").join("|") & "|\n"
  for a in reports:
    var cells = newSeq[string]()
    for i in 0 ..< RevOffsets.len:
      if a.profN[i] > 0: cells.add fmtF(a.profSum[i] / a.profN[i].float, 2)
      else: cells.add "-"
    let cellsStr = cells.join(" | ")
    s.add &"| {Arms[a.arm]} | {cellsStr} |\n"
  s.add "\n(reversal samples per arm: " &
        reports.mapIt(&"{Arms[it.arm]}={it.profN[RevOffsets.len div 2]}").join(", ") & ")\n"

  s.add "\n## 5. Direct answer\n\n"
  let base = reports[0]
  let bd = mean(values(base.runs, mDamage))
  let bw = mean(values(base.runs, mWins))
  let bht = mean(values(base.runs, mHitsTaken))
  s.add &"- control (shipped mover): damage/run {fmtF(bd)}, round wins/run {fmtF(bw)} ({int(bw*nOk(base).float)}/{nOk(base)*ArmRounds}), hits taken/run {fmtF(bht)}, reversal-pick rate {fmtF(armReversalPct(base),1)}%, mean abs(speed) {fmtF(base.speedSum/max(1,base.speedN).float)}\n"
  var anySig = false
  for ai in 1 ..< reports.len:
    let a = reports[ai]
    let d = mean(values(a.runs, mDamage))
    let w = mean(values(a.runs, mWins))
    let ht = mean(values(a.runs, mHitsTaken))
    let (pd, dd, _) = exactPermP(values(a.runs, mDamage), values(base.runs, mDamage))
    let (pw, dw, _) = exactPermP(values(a.runs, mWins), values(base.runs, mWins))
    let (ph, dh, _) = exactPermP(values(a.runs, mHitsTaken), values(base.runs, mHitsTaken))
    if pd < 0.05: anySig = true
    if pw < 0.05: anySig = true
    let vd = if pd < 0.05 and dd > 0: "HIGHER, significant"
             elif pd < 0.05 and dd < 0: "LOWER, significant"
             else: "not distinguishable from control"
    let vw = if pw < 0.05 and dw > 0: "HIGHER, significant"
             elif pw < 0.05 and dw < 0: "LOWER, significant"
             else: "not distinguishable from control"
    s.add &"- arm {Arms[a.arm]} ({a.label}): damage/run {fmtF(d)} (delta {fmtF(dd,2)}, p={fmtF(pd,4)}) -> {vd}; " &
          &"round wins/run {fmtF(w)} (delta {fmtF(dw,2)}, p={fmtF(pw,4)}) -> {vw}; " &
          &"hits taken/run {fmtF(ht)} (delta {fmtF(dh,2)}, p={fmtF(ph,4)}); " &
          &"reversal-pick rate {fmtF(armReversalPct(a),1)}% (control {fmtF(armReversalPct(base),1)}%)\n"
  s.add "\n"
  if not anySig:
    s.add "**NO ARM improves damage/run or round wins vs the shipped mover at p < 0.05.** "
  if reports.high > 0:
    var bestD = 1
    var bestW = 1
    for ai in 2 ..< reports.len:
      if mean(values(reports[ai].runs, mDamage)) > mean(values(reports[bestD].runs, mDamage)): bestD = ai
      if mean(values(reports[ai].runs, mWins)) > mean(values(reports[bestW].runs, mWins)): bestW = ai
    s.add &"Best point estimate on damage/run is arm {Arms[reports[bestD].arm]} (delta {fmtF(mean(values(reports[bestD].runs, mDamage)) - bd,2)}); " &
          &"best on round wins/run is arm {Arms[reports[bestW].arm]} (delta {fmtF(mean(values(reports[bestW].runs, mWins)) - bw,2)}). Neither is statistically distinguishable from control at this n.\n"
  s.add "\nPREMISE CHECK (the bug report claimed the tile-change replan cancels the commitment, the reversals it causes are what get us hit):\n\n"
  let rA = fmtF(armReversalPct(base), 1)
  let rB = fmtF(armReversalPct(reports[1]), 1)
  let rC = fmtF(armReversalPct(reports[2]), 1)
  let rE = fmtF(armReversalPct(reports[4]), 1)
  let tsA = fmtF(pct(base.byReason, "tile_self", base.picks), 1)
  let tsD = fmtF(pct(reports[3].byReason, "tile_enemy", reports[3].picks), 1)
  let ivA = fmtF(armInterval(base), 2)
  let ivB = fmtF(armInterval(reports[1]), 2)
  let ivE = fmtF(armInterval(reports[4]), 2)
  s.add &"- The cancel IS real and dominant in the shipped mover: arm A ends its commitment because of OUR tile change for {tsA}% of picks at a {ivA}-call interval. Arms B/C/E remove it (0.0% tile_self replans, interval {ivB} / {ivE}) and arm D re-keys it to the enemy tile ({tsD}% tile_enemy).\n"
  s.add &"- But honouring the commitment does NOT reduce reversal picks: the reversal rate RISES from {rA}% (control) to {rB}% (B) and {rE}% (E). " &
        &"The no-reversal arm C only claws part of that back ({rC}%), still above control.\n"
  s.add "- The speed dip after a reversal is present in EVERY arm (see the profile table: ~4.9 -> ~4.0 px/tick at offsets +1..+2), i.e. it is a property of turning around, not of the tile replan. Arm A -- the arm carrying the bug -- actually has the LOWEST mean abs(speed).\n"
  result = s

# ── main ─────────────────────────────────────────────────────────────────────

proc usage() =
  echo "usage: measure_tfil_commit_ab --raw <dir> [--runs N] [--first-run F] [--summary <json>] [--report <md>] [--binary-sha <sha>] [--source <commit>] [--note <text>]"
  echo "       measure_tfil_commit_ab --from-summary <json> [--report <md>]"
  quit(2)

var rawRoot  = ""
var summary  = ""
var report   = ""
var fromSum  = ""
var sha      = ""
var metaNote = ""
var src      = ""
var i = 1
while i <= paramCount():
  case paramStr(i)
  of "--raw": i.inc; rawRoot = paramStr(i)
  of "--summary": i.inc; summary = paramStr(i)
  of "--report": i.inc; report = paramStr(i)
  of "--from-summary": i.inc; fromSum = paramStr(i)
  of "--binary-sha": i.inc; sha = paramStr(i)
  of "--runs": i.inc; RunCount = parseInt(paramStr(i))
  of "--first-run": i.inc; FirstRun = parseInt(paramStr(i))
  of "--source": i.inc; src = paramStr(i)
  of "--note": i.inc; metaNote = paramStr(i)
  else: usage()
  i.inc
if rawRoot.len == 0 and fromSum.len == 0: usage()

if fromSum.len > 0:
  ## Re-render the committed summary without needing the raw artifacts.
  let root = parseFile(fromSum)
  var reports: seq[ArmReport]
  for arm in 0 ..< Arms.len:
    var a: ArmReport
    a.arm = arm
    a.env = ArmEnv[arm]
    a.label = ArmLabel[arm]
    a.byReason = initTable[string, int]()
    a.profSum = newSeq[float](RevOffsets.len)
    a.profN = newSeq[int](RevOffsets.len)
    let ja = root["arms"][Arms[arm]]
    a.picks = ja["diag"]["picks"].getInt()
    a.commitCalls = ja["diag"]["commitCalls"].getInt()
    a.intervalSum = int(ja["diag"]["intervalMean"].getFloat() * a.picks.float)
    a.revPicks = ja["diag"]["revPicks"].getInt()
    a.speedSum = ja["diag"]["speedMean"].getFloat() * a.commitCalls.float
    a.speedN = a.commitCalls
    for k, v in ja["diag"]["byReason"]:
      a.byReason[k] = v.getInt()
    for idx in 0 ..< ja["diag"]["speedProfile"].len():
      let v = ja["diag"]["speedProfile"][idx]
      if v.kind != JNull:
        # the stored value is already the arm-level MEAN; keep it as a mean by
        # storing mean*count in the sum slot
        let n = ja["diag"]["speedProfileN"][idx].getInt()
        a.profN[idx] = n
        a.profSum[idx] = v.getFloat() * n.float
    for jr in ja["runs"]:
      var m: RunMetrics
      m.run = jr["run"].getInt()
      m.damageDealt = jr["damageDealt"].getFloat()
      m.damageTaken = jr["damageTaken"].getFloat()
      m.wins = jr["wins"].getInt()
      m.hitsTaken = jr["hitsTaken"].getInt()
      m.shots = jr["shots"].getInt()
      m.score = jr["score"].getInt()
      m.enemyScore = jr["enemyScore"].getInt()
      m.ticks = jr["ticks"].getInt()
      m.rounds = jr["perRoundWins"].len
      for w in jr["perRoundWins"]: m.perRoundWins.add w.getInt()
      if jr.hasKey("note"): m.note = jr["note"].getStr()
      if jr.hasKey("winsByDeath"): m.winsByDeath = jr["winsByDeath"].getInt()
      if jr.hasKey("reversalPct"): m.reversalPct = jr["reversalPct"].getFloat()
      if jr.hasKey("intervalMean"): m.intervalMean = jr["intervalMean"].getFloat()
      if jr.hasKey("picks"): m.picks = jr["picks"].getInt()
      if jr.hasKey("revPicks"): m.revPicks = jr["revPicks"].getInt()
      m.ok = true
      a.runs.add m
    reports.add a
  let m = root["meta"]
  let meta = buildMetaS(
    (if m.hasKey("note"): m["note"].getStr() else: ""),
    (if m.hasKey("source"): m["source"].getStr() else: ""),
    (if m.hasKey("binarySha256"): m["binarySha256"].getStr() else: ""),
    m["rawRoot"].getStr(), m["runsPerArm"].getInt())
  let txt = buildReport(reports, meta)
  stdout.write txt
  if report.len > 0:
    writeFile(report, txt)
    echo "\nwrote ", report
  quit(0)

# extraction mode
var reports: seq[ArmReport]
for arm in 0 ..< Arms.len:
  reports.add aggregate(rawRoot, arm)

let meta = buildMetaS(metaNote, src, sha, rawRoot, RunCount)
let txt = buildReport(reports, meta)
stdout.write txt
if report.len > 0:
  writeFile(report, txt)
  echo "\nwrote ", report

if summary.len > 0:
  var root = %*{
    "meta": {"source": src, "binarySha256": sha, "rawRoot": rawRoot,
             "arms": ArmEnv, "runsPerArm": RunCount, "roundsPerRun": ArmRounds,
             "note": metaNote,
             "roundWinsSource": "final RESULTS firstPlaces, cross-checked with BotDeathEvent",
             "damageSource": "BulletHitBotEvent damage, attributed by numeric owner/victim id (verified against the capture's own counters)"},
    "arms": %*{}
  }
  for a in reports:
    var runs = newJArray()
    for m in a.runs:
      runs.add %*{
        "run": m.run, "rounds": m.rounds, "wins": m.wins,
        "winsByDeath": m.winsByDeath, "perRoundWins": m.perRoundWins,
        "score": m.score, "enemyScore": m.enemyScore, "ticks": m.ticks,
        "damageDealt": m.damageDealt, "damageTaken": m.damageTaken,
        "shots": m.shots, "enemyShots": m.enemyShots,
        "hits": m.hits, "hitsTaken": m.hitsTaken,
        "commitCalls": m.commitCalls, "picks": m.picks,
        "intervalMean": m.intervalMean, "revPicks": m.revPicks,
        "reversalPct": m.reversalPct, "speedMean": m.speedMean,
        "byReason": m.byReason, "note": m.note
      }
    var byReason = %*{}
    for k, v in a.byReason: byReason[k] = %v
    var prof = newJArray()
    var profN = newJArray()
    for idx in 0 ..< RevOffsets.len:
      if a.profN[idx] > 0: prof.add %(a.profSum[idx] / a.profN[idx].float)
      else: prof.add newJNull()
      profN.add %a.profN[idx]
    root["arms"][Arms[a.arm]] = %*{
      "label": a.label, "env": a.env, "runs": runs,
      "diag": {"commitCalls": a.commitCalls, "picks": a.picks,
               "intervalMean": armInterval(a), "revPicks": a.revPicks,
               "reversalPct": armReversalPct(a),
               "speedMean": a.speedSum / max(1, a.speedN).float,
               "byReason": byReason, "revOffsets": RevOffsets,
               "speedProfile": prof, "speedProfileN": profN}
    }
  createDir(summary.parentDir)
  writeFile(summary, pretty(root, 2))
  echo "wrote ", summary