[SITE]
Domain: bukittimahtutor.com
Place:  SGP.SG.BT
Lane:   EDU.MATH.SEC12
Role:   Repair Router (Truncation + Stitching)
Zoom:   Z0–Z3
v:      v1.0

[NODE]
SGP.SG.BT×EDU.MATH.SEC12×Z3×V×LOCK×BTT.SEC12.PURPOSE×v1.0:
  txt: "Sec 1–2 Math is the symbol-and-structure gateway: algebra + number structure + representation. BTT prevents collapse by repairing decoding, representation, and error loops before speed."
[EDGE]
binds_to:
  SGP.SG.BT×EDU×Z3×R×PROTOCOL×BTT.REPAIR_ROUTING×v1.0
  SGP.SG.BT×EDU.MATH×Z3×S×PHASE×P0P3.MATH×v1.0

[NODE]
SGP.SG.BT×EDU.MATH.SEC12×Z0×L×PRIM×SEC12.SYMBOL_DECODING×v1.0:
  def: "read algebra correctly; interpret '='; interpret brackets; interpret indices; interpret fractions as structure"
[NODE]
SGP.SG.BT×EDU.MATH.SEC12×Z0×L×PRIM×SEC12.ALGEBRA_FOUNDATION×v1.0:
  def: "treat letters as variables; manipulate expressions legally; maintain equivalence"
[NODE]
SGP.SG.BT×EDU.MATH.SEC12×Z0×L×PRIM×SEC12.NUMBER_STRUCTURE×v1.0:
  def: "real numbers, integers, factors/multiples, rational structure; sign discipline"
[NODE]
SGP.SG.BT×EDU.MATH.SEC12×Z1×L×PRIM×SEC12.REPRESENTATION_MODELS×v1.0:
  def: "translate word problems into structure; bar models evolve into algebraic models"
[NODE]
SGP.SG.BT×EDU.MATH.SEC12×Z1×L×PRIM×SEC12.ERROR_LOOP×v1.0:
  def: "detect and localise errors independently in multi-step algebra"
[NODE]
SGP.SG.BT×EDU.MATH.SEC12×Z2×L×PRIM×SEC12.TRANSFER_STARTER×v1.0:
  def: "start unfamiliar problems using decomposition templates"

[NODE]
SGP.SG.BT×EDU.MATH.SEC12×Z3×S×PHASE×P0P3.SEC12×v1.0:
  P3:
    - "algebra is natural language"
    - "starts problems independently"
    - "self-corrects signs/steps"
    - "handles novel word problems"
  P2:
    - "can do standard forms"
    - "brittle under word problems / mixed topics"
  P1:
    - "procedural memory; frequent sign errors"
    - "slow; uncertain; depends on hints"
  P0:
    - "cannot start; avoidance; shutdown"

[NODE]
SGP.SG.BT×EDU.MATH.SEC12×Z3×R×TRACE×BTT.SEC12.FAILURE_MODE×v1.0:
  chain:
    - "Z0: weak decoding of symbols (brackets/fractions/indices/signs)"
    - "Z0: illegal algebra steps (equivalence broken)"
    - "Z1: representation fails (word problems not translated)"
    - "Z1: error loop externalised (needs teacher to locate mistakes)"
    - "Z2: mixed-topic transfer fails; student freezes"
  phase_drift:
    - "P2 primary illusion → P1 secondary fragility → P0 under exam speed"
  repair_route:
    - "truncate speed → rebuild decoding → rebuild equivalence → rebuild representation → restore error loop → restore transfer → add time last"

[NODE]
SGP.SG.BT×EDU.MATH.SEC12×Z0×R×TRACE×BTT.SEC12.CLUSTER.SIGN_STRUCTURE×v1.0:
  symptoms:
    - "sign flips incorrectly"
    - "negative distribution errors"
    - "fraction sign mistakes"
  root:
    - "number structure + symbol decoding weak"
  fix:
    - "sign discipline protocol + micro-drills + forced verbalisation of structure"

[NODE]
SGP.SG.BT×EDU.MATH.SEC12×Z0×R×TRACE×BTT.SEC12.CLUSTER.EQUIVALENCE_BREAK×v1.0:
  symptoms:
    - "cancels terms incorrectly"
    - "moves terms with wrong operation"
    - "changes expression meaning"
  root:
    - "equivalence concept missing"
  fix:
    - "equivalence guards: 'same value' checks; reverse-substitution verification"

[NODE]
SGP.SG.BT×EDU.MATH.SEC12×Z1×R×TRACE×BTT.SEC12.CLUSTER.WORD_FREEZE×v1.0:
  symptoms:
    - "cannot start"
    - "writes random equations"
  root:
    - "representation model missing"
  fix:
    - "decomposition templates: known/unknown/relations; convert language→structure"

[NODE]
SGP.SG.BT×EDU.MATH.SEC12×Z2×R×TRACE×BTT.SEC12.CLUSTER.MIXED_TRANSFER×v1.0:
  symptoms:
    - "works in chapter practice, fails mixed tests"
  root:
    - "transfer starter missing"
  fix:
    - "mixed-topic sorting protocol + method-selection cues"

[NODE]
SGP.SG.BT×EDU.MATH.SEC12×Z3×R×PROTOCOL×BTT.SEC12.REPAIR×v1.0:
  TRUNCATE:
    - "remove time pressure temporarily"
    - "stop long mixed worksheets until decoding stable"
  REBUILD_1 (S0 DECODING):
    - "notation reading"
    - "brackets/fractions/indices parsing"
    - "sign structure discipline"
  REBUILD_2 (EQUIVALENCE):
    - "what operations preserve equality"
    - "legal manipulation rules"
    - "verification habit (substitute/check)"
  REBUILD_3 (REPRESENTATION):
    - "word→structure templates"
    - "units/labels"
    - "diagram-to-equation conversion"
  REBUILD_4 (ERROR LOOP):
    - "error detection"
    - "error localisation"
    - "self-correction scripts"
  REBUILD_5 (TRANSFER STARTER):
    - "problem decomposition"
    - "mixed-topic method selection"
  TIME (ONLY AFTER STABLE):
    - "first-step speed"
    - "accuracy under mild time"
  SPEED LAST:
    - "increase velocity only when variance low"

[NODE]
SGP.SG.BT×EDU.MATH.SEC12×Z0×R×METRIC×BTT.SEC12.SENSOR.DECODE_ERROR×v1.0:
  def: "notation parsing error rate (brackets/fractions/indices/signs)"
[NODE]
SGP.SG.BT×EDU.MATH.SEC12×Z0×R×METRIC×BTT.SEC12.SENSOR.EQUIV_BREAK×v1.0:
  def: "illegal-step frequency (equivalence broken)"
[NODE]
SGP.SG.BT×EDU.MATH.SEC12×Z1×R×METRIC×BTT.SEC12.SENSOR.START_LATENCY×v1.0:
  def: "time to first meaningful equation/model on word problems"
[NODE]
SGP.SG.BT×EDU.MATH.SEC12×Z2×R×METRIC×BTT.SEC12.SENSOR.MIXED_TEST_DROP×v1.0:
  def: "drop rate from chapter practice to mixed test performance"

[LOCKBLOCK:BTT.SEC12_MATH.v1.0]
Sec 1–2 Math is the symbol gateway. Collapse usually starts at decoding + equivalence + representation.
BTT repairs in order: truncate → decode → equivalence → representation → error loop → transfer starter → time → speed last.
Target: P3 (independent start + self-correct + transfer), not P1 procedural cram.