SYSTEM: Education OS
HUB: Singapore Secondary Subject OS Directory
CITY/NATION: SGP-SIN / SGP
ZOOM LINK: Z5 (city) ↔ Z0 (student)
GATE PLUG-IN:
  - O-Level OS (Singapore)
  - (downstream) PSLE OS link (for foundation references)
REFERENCE: CivOS (P0–P3)
PRIMARY PURPOSE:
  Provide a standard executable directory for Sec 1–4 subjects:
    - mastery (P3)
    - top failure modes (GF*)
    - sensor pack (P-S* + subject sensors)
    - repair loops (GR*)
    - O-Level proofs (OL-S*)

SEC 1–4 SUBJECT OS SET (SGP):
  - SGP Secondary English OS (Sec 1–4)
  - SGP Secondary E-Math OS (Sec 1–4)
  - SGP Secondary A-Math OS (Sec 3–4)  [Sec2→3 jump protected]
  - SGP Secondary Science OS (Sec 1–2)
  - SGP O-Level Physics OS (Sec 3–4)
  - SGP O-Level Chemistry OS (Sec 3–4)
  - SGP O-Level Biology OS (Sec 3–4)

SUBJECT_ENTRY_SCHEMA:
  SUBJECT_ID: <SGP-SEC-...> (stable)
  SUBJECT_NAME: <string>
  YEARS: <Sec1–Sec4 or Sec3–Sec4>
  VERIFICATION GATE:
    - O-Level OS (Singapore)
  P3 MASTERY:
    - (retrieval, transfer, timed reliability, recovery)
  TOP FAILURE MODES:
    - 8–12 modes mapped to GF*
  SENSOR PACK:
    - P-S1..P-S5
    - subject-specific sensors
    - O-Level proof sensors (OL-S*)
  REPAIR LOOPS:
    - GR1, GR2, GR3, GR4, GR6, GR8
    - plus GR5/GR11/GR12 when applicable
  FAILURE TRACE + REPAIR TRACE:
    - required schematic chain
  PORTS:
    - O-Level OS, PSLE OS, GF library, GR library

PHASE SENSORS (SECONDARY STANDARD):
  P-S1 retrieval reliability
  P-S2 error histogram (concept/execution/attention)
  P-S3 time-to-solve distribution
  P-S4 transfer under wrapper variation
  P-S5 timed stability variance

O-LEVEL PROOF SENSORS (SECONDARY STANDARD):
  OL-S1 Sec2→Sec3 jump risk (for A-Math + abstraction-heavy subjects)
  OL-S2 multi-subject stability index
  OL-S3 timed vs untimed gap
  OL-S4 transfer gap under novelty
  OL-S5 error-repeat density
  OL-S6 repair latency vs exam horizon
  OL-S7 tuition masking factor (dependency vs competence)
  OL-S8 burnout risk proxy

SECONDARY DOMINANT GF CLUSTER (SGP):
  GF1 language drift (worded questions)
  GF2 practice without model
  GF3 compression without buffers
  GF5 transition shock amplification (Sec2→3)
  GF6 timed execution collapse
  GF7 late repair trap
  GF8 tuition masking
  GF9 transfer failure under novelty
  GF12 burnout tail

SECONDARY DOMINANT GR SET (SGP):
  GR8 early-warning thresholds
  GR1 buffer build (concept spine)
  GR3 transfer audits (wrapper robustness)
  GR4 time-pressure loop (timed stability)
  GR2 error-log closure (repeat elimination)
  GR6 continuity loop (coordination stabiliser)
  GR11 pressure-safety scheduling (burnout control)
  GR12 algebra readiness stabilisation (Sec2→Sec3 protection)
  GR5 language-base loop (when GF1 present)
  GR7 masking control (proof-based independence)

SUBJECT_ID: SGP-SEC-EMATH
SUBJECT_NAME: Singapore Secondary E-Math OS
YEARS: Sec1–Sec4
VERIFICATION GATE: O-Level OS (Singapore)
P3 MASTERY:
  - retrieves methods without cues (P-S1)
  - transfers across worded/graphical/symbolic wrappers (P-S4)
  - executes under time with low volatility (P-S5)
  - sustains mixed-topic papers; recovers after mistakes
TOP FAILURE MODES:
  EM-F01 algebra base gaps (feeds Sec3 jump) (GF5 precursor)
  EM-F02 practice without model (GF2)
  EM-F03 word-problem wrapper collapse (GF1+GF9)
  EM-F04 timed collapse (GF6)
  EM-F05 topic partitioning (fails on mixed papers) (GF9)
  EM-F06 error-repeat density (no closure) (GF10 symptom)
  EM-F07 late repair trap (GF7)
  EM-F08 burnout tail (GF12)
SUBJECT SENSORS:
  EM-S1 algebra primitives integrity score
  EM-S2 method-selection accuracy on mixed sets
  EM-S3 worded-wrapper transfer score
  EM-S4 checking discipline rate
REPAIR LOOPS:
  {GR1, GR3, GR4, GR2, GR6, GR8} + {GR5 if worded drift} + {GR11 if overload}
PROOF (O-LEVEL READY hooks):
  - OL-S3 timed gap small
  - OL-S4 transfer holds across wrapper families
  - OL-S5 error-repeat density falling

SUBJECT_ID: SGP-SEC-AMATH
SUBJECT_NAME: Singapore Secondary A-Math OS
YEARS: Sec3–Sec4
VERIFICATION GATE: O-Level OS (Singapore)
P3 MASTERY:
  - stable algebra manipulation + functions without cues
  - transfers across unfamiliar forms and mixed synthesis
  - executes under time with low volatility
  - recovers after chain breaks
TOP FAILURE MODES:
  AM-F01 Sec2→Sec3 algebra/abstraction jump collapse (GF5 signature)
  AM-F02 weak algebra primitives (GR12 required) (GF5 precursor)
  AM-F03 practice without model (GF2)
  AM-F04 transfer collapse on novel forms (GF9)
  AM-F05 timed execution collapse (GF6)
  AM-F06 chain-break instability (multi-step collapse) (AL-S1 analog)
  AM-F07 late repair trap (GF7)
  AM-F08 burnout tail (GF12)
SUBJECT SENSORS:
  AM-S1 algebra readiness index (maps to OL-S1)
  AM-S2 chain-break map (where steps fail)
  AM-S3 novelty transfer score (form variation)
  AM-S4 timed volatility (P-S5 focused)
REPAIR LOOPS:
  GR12 (signature) + GR8 + GR1 + GR3 + GR4 + GR2 + GR6 + (GR11 if overload)
PROOF (O-LEVEL READY hooks):
  - OL-S1 Sec3 jump risk low
  - OL-S3 timed gap small
  - OL-S4 transfer holds across novel forms
  - OL-S5 repeats collapse

SUBJECT_ID: SGP-SEC-ENG
SUBJECT_NAME: Singapore Secondary English OS
YEARS: Sec1–Sec4
VERIFICATION GATE: O-Level OS (Singapore)
P3 MASTERY:
  - reads unseen texts accurately under time
  - answers by command-word compliance
  - writes coherent, structured responses with stable quality
  - transfers across genres/prompts without collapse
TOP FAILURE MODES:
  EN-F01 vocabulary/comprehension drift (GF1)
  EN-F02 writing structure instability under time (GF6)
  EN-F03 prompt-wrapper sensitivity (GF9)
  EN-F04 practice without model (templates only) (GF2→GF9)
  EN-F05 late repair trap (GF7)
  EN-F06 burnout tail (GF12)
SUBJECT SENSORS:
  EN-S1 command-word compliance rate
  EN-S2 comprehension accuracy under time
  EN-S3 output structure stability (paragraph logic)
  EN-S4 prompt transfer score
REPAIR LOOPS:
  GR5 + GR1 + GR3 + GR4 + GR2 + GR6 + GR8 + (GR11 if overload)
PROOF (O-LEVEL READY hooks):
  - OL-S3 timed gap reduced
  - OL-S4 transfer holds across unseen prompts
  - volatility low across papers

PORTS (HUB):
  - O-Level OS (Singapore)  [primary gate]
  - PSLE OS (Singapore)     [foundation reference]
  - Singapore City Education OS (SGP-SIN)
  - Singapore Nation Education OS (SGP)
  - W4 GF Library
  - W5 GR Library
  - Comparatives:
      London↔Singapore (Z5)
      UK↔SGP (Z6)