build/20260612 062318/0050 json helper consolidation

[cahenesy]

• test(failing): json.sh canonical escaper/array/field-reader unit eval (TDD 0050 step 1; Verification §1/§3/§6)
• step(1): create scripts/lib/json.sh — canonical C0-safe escaper, compact array builders, quote-aware field reader (TDD 0050 §1; FR-27, FR-69)
• test(failing): A11/A3 strict-parse + A10/A5 quote-roundtrip regressions against state.sh's escaper and primary reader (TDD 0050 step 2; Verification §2/§6)
• step(2): wire state.sh through json.sh — json_escape delegates (A11), 4 inline array builders -> tl_json_array, _read_fragment_field -> tl_json_field (A10/A5) (TDD 0050 §2; FR-27, FR-39)
• test(failing): markers.sh delegation observables — json.sh bound on source, compact _tl_csv_to_json_array (TDD 0050 step 3; Verification §4)
• step(3): wire markers.sh through json.sh — _tl_json_escape + _tl_csv_to_json_array delegate; compact-array pin updated in lifecycle-helpers eval (TDD 0050 §3)
• test(failing): learnings.sh delegation — json.sh bound on standalone source, _json_str_array via tl_json_array_ws, C0-safe A3 path (TDD 0050 step 4; Verification §4)
• step(4): wire learnings.sh through json.sh — _json_str_array delegates to tl_json_array_ws; candidate-learnings writes ride the C0-safe escaper (A3) (TDD 0050 §4; FR-72)
• test(failing): drafts.sh third escaper (_tl_json_escape_full) deleted; canonical tl_json_escape bound (TDD 0050 step 5; Verification §5)
• step(5): drafts.sh drops _tl_json_escape_full — callers use the canonical tl_json_escape; stale C0-gap comments synced (TDD 0050 §5; FR-46)
• test(failing): gates.sh binds json.sh on standalone source; _step_block_entry pattern_tags pinned through the canonical builder (TDD 0050 step 6; Verification §4)
• step(6): wire gates.sh through json.sh — _step_block_entry pattern_tags via tl_json_array; consumer owns its source line (TDD 0050 §6; FR-72)
• test(failing): §4 context matrix, §5 single-source grep, §W aggregator wire-in dogfood (TDD 0050 step 7; TDD 0038 §3 wire-in rule)
• step(7): register json-helper eval in the ci-checks aggregator (JSH AND-chain term); bump plugin 3.35.0 -> 3.36.0 (TDD 0050 §7; FR-69)
• tdd(0050): reconcile Expected diff size + Touched files to measured build churn (numstat adds+dels; replaced bodies count twice)
• mark 0050-json-helper-consolidation implemented (verified + reviewed)

[cahenesy]

Per-requirement coverage map (FR-78 — reported, advisory): see the ## Per-requirement coverage section in this run's report at /home/chris/hogv/open-source/throughline/docs/tdd/.implement-logs/20260612-062318/report.md. An unverified-gap there is a finding for the human reviewer, not an automatic block.