docs(R2-Q0): motion-table research base + ambiguity pins

- r2-motiontable-decomp.md: 1,603-line verbatim extraction — full
  CMotionTable (GetObjectSequence all 4 class branches, get_link,
  is_allowed, re_modify, StopSequenceMotion, SetDefaultState, wrappers),
  the free functions (add/combine/subtract_motion, change_cycle_speed,
  same_sign), all 16 MotionTableManager members (pending_animations,
  add_to_queue, remove_redundant_links with the 0xb0000000/0x70000000
  block masks, truncate, AnimationDone vs CheckForCompletedMotions,
  PerformMovement with the 0x41000003 stop sentinel), MotionState's
  full modifier-stack/action-FIFO cast, verbatim struct layouts +
  constants table. BN mistypings identified (SurfInfo lookups are
  style_defaults/links hashes).
- r2-ace-motiontable.md: ACE cross-ref with the two-tracker headline
  (MotionTableManager UPSTREAM of MotionInterp — never merged) + 5
  flagged ACE oddities.
- r2-port-plan.md: 17 gaps (H1-H17), keep list, Q0-Q6 commit sequence,
  the MotionDone->R3 boundary contract.
- Q0-pins.md: A1/A2 pinned to ACE's reading (three corroborations;
  cdb confirmation folds into the next live session), A3 outTicks
  decode, A4 ACE-oddity adjudications (the Action-branch double-count
  is an ACE bug — do not copy), A5 Bitfield check at Q2.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docs/research/2026-07-02-r2-motiontable/Q0-pins.md

@@ -0,0 +1,43 @@
+# R2-Q0 — ambiguity pins and ACE-oddity adjudications
+
+The verbatim extraction is `r2-motiontable-decomp.md` (1,603 lines, line-anchored);
+the port plan with the full ambiguity table is `r2-port-plan.md` §0. This note
+records the PINNED resolutions the Q1–Q5 ports code against.
+
+## Pinned
+
+- **A1 — `get_link` branch predicate: PINNED to ACE's reading** ("EITHER speed
+  negative → swapped-key branch"). Three independent corroborations: ACE
+  `MotionTable.cs:395-426`; the working adapter's field-validated `GetLink`
+  (the reversed-key branch fixed the Ready→WalkBackward glitch); call-site arg
+  roles. The BN "both negative" reading is the same x87-flag-noise class as
+  `is_newer`'s garbled setcc and the R1 hook-direction swap. cdb confirmation
+  (bp `CMotionTable::get_link`, Ready→WalkBackward vs Ready→WalkForward)
+  folds into the next live retail session — non-blocking.
+- **A2 — Branch-2 `signedSpeed`: PINNED to ACE** (`SubstateMod < 0 &&
+  speedMod > 0 → -speedMod`, the single-direction flip) pending the same cdb
+  session (golden: a Walk(−)→Walk(+) flip).
+- **A3 — outTicks** = sum of each appended MotionData's `num_anims` (+ base
+  cycle in Branch 1/2) − 1. The `action_head` rendering in BN is the packed
+  `num_anims` byte (decomp's own note).
+- **A4 — ACE oddities adjudicated:** (1) Action-branch numAnims double-count =
+  ACE BUG, do not copy (retail sums outHop + actionLink [+ returnHop] only);
+  (2) `change_cycle_speed` old≈0 silent no-op = RETAIL (port verbatim,
+  including the gap); (3) `GetLinkData` 0xFFFF mask = ACE-only helper, not
+  ported; (4) `StopObjectCompletely` return = `finalStopOk ? 1 :
+  anyModifierStopOk`, port verbatim; (5) `re_modify` snapshot = deep-copied
+  MotionState used ONLY as the loop-termination bound — C# port deep-copies,
+  pops both, terminates on snapshot empty.
+- **A5 — `MotionData.Bitfield`** (bit1 = substate-gated for `is_allowed`,
+  bit0 = clear-modifiers-on-entry): confirm on DatReaderWriter
+  `Types.MotionData` with a one-line Humanoid-table test at Q2.
+
+## Q0 cdb capture (pending, non-blocking)
+
+One live session feeds all R2 goldens: bp GetObjectSequence / get_link /
+StopSequenceMotion / add_to_queue / remove_redundant_links /
+truncate_animation_list / AnimationDone / CheckForCompletedMotions with
+arg+ret logging (pattern `tools/cdb/l2g-observer.cdb`); protocol per
+`r2-port-plan.md` §0. Until then Q2/Q3 rest on dat fixtures + synthetic
+state tables + the archived 2026-05-03 walk→run trace golden (quoted in the
+old Fix B comment block).