record_emit: format-opaque record serialization via ConfigFormat

[briansrls]

Summary

Collapses 3 forked knob models (OutputFormat, FormatModel, RecordSyntax) into the SerializationKnobs residue after decomposing OutputFormat by re-homing each field: name → ConfigFormat.name, comment_prefix → CommentSyntax.line_prefix, indent_unit → LayoutProtocol.indent_unit. Adds serialize_record → Doc (recursive: ScalarValue | RecordValue) in a new std.serialize module. Migrates the runner manifest byte-identically to the new API. Proves format-opacity on the real projection via a JSON swap on the same manifest_host_fields.

Changes

std/languages.dag

• Deleted dead FormatModel (uninhabited, zero data instances, zero refs)
• Replaced RecordSyntax with SerializationKnobs { assign, entry_separator, open, close, quote_keys, value_quote }
• Added SerialField { key, value: SerialValue } and SerialValue = ScalarValue | RecordValue (mutual recursion — same pattern as YamlKeyValue ↔ YamlValue)
• ConfigFormat.record: SerializationKnobs? — all 5 format rows updated
• Added json_record_knobs data, plus value_quote_escape_dissolution_trigger (§5 honesty: value_quote is a wrap-char concat(q,t,q), NOT RFC-8259 escaping; current manifest values contain no quotes/newlines so no live bug; dissolution = real string-escape authority citing RFC 8259 §7 and TOML v1.0 §String)

std/serialize.dag (new module)

• serial_scalar, serial_field constructors
• serialize_field_doc, serialize_fields_doc (intersperse by entry_separator, no leading/trailing), serialize_record_doc (wrap with open/close) → all produce Doc; recursive via RecordValue → serialize_record_doc

std/render.dag

• Removed RecordSyntax import, removed serialize_config_record_entry
• Added output_format_dissolution_trigger (OutputFormat.name/comment_prefix/indent_unit re-home; one live consumer extdeps.git.gitignore → follow-on child)

gunbc/runner_deploy_emit.dag (real consumer — byte-identical)

• Added manifest_record_knobs: SerializationKnobs (assign="=", entry_separator=" ", no quoting)
• Replaced manifest_host_text → manifest_host_fields + manifest_host_doc; session_host_text → session_host_fields + session_host_doc; operating_row_text → operating_row_fields + operating_row_doc
• Added expected_runner_deploy_manifest_json() — renders ACTUAL host records via manifest_host_fields(h) through json_record_knobs (same business logic, knobs swapped)

test/claim/config_record_emit_test.dag — witnesses using new API, plus JSON swap:

• witness_manifest_knobs_space_separated, witness_json_knobs_produce_quoted_record, witness_same_fields_differ_across_knobs (discriminating: same List → different output under each knob)

test/claim/runner_placement_witness_test.dag — real-projection swap acid test:

• witness_real_manifest_fields_drive_both_formats: uses actual runner_deployment_plan() hosts; for each real host h, asserts manifest_host_doc(h) and serialize_record_doc(json_record_knobs, manifest_host_fields(h)) produce different text from the same fields, identity present in format-appropriate form in each
• Restored starts_with teeth in witness_sound_manifest_line_is_populated

Real swap output (verified on live deployment plan)

Same manifest_host_fields(h) projection — only the knobs value swapped:

text: runner-deploy host=srv1 runner_count=10 ... labels=self-hosted,linux,arm64 cpu_weight=100
json: runner-deploy {"host": "srv1", "runner_count": "10", ..., "labels": "self-hosted,linux,arm64", "cpu_weight": "100"}

Known boundary: expected_runner_deploy_manifest_json() keeps the per-line "runner-deploy " prefix → prefixed-NDJSON, not a consumable JSON document. That is correct for the swap demonstrator (proves record-spelling opacity). A real .json artifact dropping the prefix and rendering hosts as a JSON array is a follow-on C-series concern, not this PR.

Execution receipts

$ gunbc run --source-root dsl --source-root src/v2 --claim-run \
    --entry dsl/test/claim/config_record_emit_test.dag \
    --function config_record_emit_keystone_holds
running config_record_emit_keystone_holds()...
true

$ gunbc run --source-root dsl --source-root src/v2 --claim-run \
    --entry dsl/test/claim/runner_placement_witness_test.dag \
    --function runner_placement_holds
running runner_placement_holds()...
true

$ gunbc compile --source-root dsl --source-root src/v2 --target dag \
    --dependency-pool-index primary-precedence --dry-run
indexed 1510 modules from 2 source roots
resolved 684 sources
0 diagnostics

Independently verified green by parent session (clever-raven-585) on cd316ad.