core/docs/adr/ADR-0083-transitive-chain-surface.md

ADR-0083 — Transitive Chain Surface (Bounded Multi-Hop Composition)

Status: Accepted Date: 2026-05-20 Author: Shay

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Context

ADR-0062 introduced depth-1 chain-of-chains composition (teaching_grounded_surface_composed): given a ratified chain (A, intent_A, conn_A, B) and a follow-up (B, intent_B, conn_B, C), emit a two-clause surface

A {conn_A} B (dB), which {conn_B} C (dC).

The composer is opt-in (RuntimeConfig.composed_surface=False), cycle-guarded, pack-residency-guarded, and degrades byte-identically to the single-chain surface when no follow-up exists. On the 21-chain saturation-v2 cognition corpus, follow-up resolution succeeds for ~12 chains.

What's still missing

ADR-0062 explicitly defers deeper composition:

v1 follows exactly one hop. Deeper compositions (A→B→C→D) are deferred to a future ADR.

Inspection of the holdout misses (memory: dev-holdout-generalization-2026-05-18, adr-0053-cognition-lane-closure) and the cognition saturation corpus shows several latent depth-2 paths that today's composer cannot reach:

Hop 1	Hop 2	Hop 3
inference requires evidence	evidence grounds knowledge	knowledge requires evidence (cycle — stops at hop 2)
thought reveals meaning	meaning grounds understanding	understanding requires knowledge
light reveals truth	truth grounds knowledge	knowledge requires evidence
definition grounds concept	concept requires definition (cycle — stops at hop 1)	—

Three of these would emit a three-clause surface today if the composer could follow a second hop with cycle tracking; the fourth demonstrates the cycle guard already does its job at depth 1 and must extend to depth N.

Why this is the next architectural step

The repo's φ separation probe (memory: phi separation falsified) made it explicit that semantic "stress" or "contradiction" cannot currently be encoded geometrically — the working semantic engine is pack-grounded chain composition over ratified teaching corpora. That engine is the cognition surface. Its depth ceiling is therefore the cognition surface's depth ceiling.

ADR-0083 raises that ceiling by one constant per release: depth-2 now, with the visited-set machinery to support depth-N later under the same flag.

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Decision

Add teaching_grounded_surface_transitive(subject, intent_tag, *, max_depth) to chat/teaching_grounding.py alongside the existing single-chain and composed (depth-1) composers. Route it via a new opt-in RuntimeConfig.transitive_surface: bool = False and a separate RuntimeConfig.transitive_max_depth: int = 2.

Surface format

"{A} — teaching-grounded ({corpus_id}): {dA1}; {dA2}.
 {A} {conn_A} {B} ({dB1}), which {conn_B} {C} ({dC1}), which {conn_C} {D} ({dD1}).
 No session evidence yet."

Each additional hop adds one ", which {conn_k} {X_k} ({dX_k1})" clause before the trailing period. The , which linker is reused from ADR-0062; no new template constants.

Follow-up resolution rules

Reuse ADR-0062's per-hop rules, applied iteratively:

1. Resolve the initial chain (subject, intent). If absent, return None.
2. For each hop k ∈ {1, ..., max_depth - 1}: a. Look up (X_k.object, "cause"); fall back to (X_k.object, "verification"). b. Visited-set guard. Maintain visited = {subject, X_1.object, ..., X_k.object}. Refuse a candidate whose object is in visited (closes the ADR-0062 cycle guard at every depth). c. Pack-residency guard. Refuse a candidate whose object is not pack-resident with semantic_domains in the candidate's resolving corpus's pack. d. Cross-corpus guard. v1 requires all hops to resolve in the same corpus (spec.corpus_id == initial.corpus_id). ADR-0064 cross-corpus chains exist, but transitive composition across corpora needs its own audit — deferred. e. If no candidate survives, stop and emit whatever depth has accumulated so far.
3. If no hop survived past the initial chain, degrade byte-identically to the ADR-0062 composed surface (which itself degrades to the single-chain surface).

Bounded depth

transitive_max_depth: int = 2 is the v1 default — equivalent to one additional hop beyond ADR-0062's composed surface. The config field is exposed so operators can characterise depth-3 / depth-4 on their workloads before any default change is proposed. The runtime clamps to max(1, transitive_max_depth) so a misconfigured 0 degrades gracefully to single-chain.

Opt-in flag

RuntimeConfig.transitive_surface: bool = False. Default preserves all pre-ADR-0083 behaviour byte-identically. Mirrors the ADR-0047/0058/0062 pattern: ship the capability behind a flag, characterise empirically, decide on default behaviour in a follow-up.

The flag composes with composed_surface:

composed_surface	transitive_surface	Behaviour
False	False	single-chain (pre-ADR-0062)
True	False	depth-1 composed (ADR-0062)
*	True	depth-N transitive (ADR-0083, overrides composed)

transitive_max_depth is the number of follow-up hops to append beyond the initial chain. At max_depth=0 transitive degrades byte-identically to single-chain; at max_depth=1 byte-identical to ADR-0062's composed surface; at max_depth=2 byte-identical to ADR-0062 when no second hop survives the guards, strict superset when one does.

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Verification

Required tests (new file: tests/test_transitive_surface.py)

• Pure function:
  • returns None when no chain / initial-only / depth-1 / depth-2;
  • emits an N-clause surface (N ≤ max_depth) when chains chain;
  • includes every intermediate object as a clause subject;
  • includes every intermediate semantic_domains head;
  • deterministic across two calls;
  • visited-set guard blocks a depth-N cycle at every depth from 2 to max_depth;
  • pack-residency guard blocks at any depth (not just depth-1);
  • cross-corpus guard refuses to traverse a cross-corpus follow-up.
• Runtime:
  • default keeps single-chain;
  • composed_surface=True, transitive_surface=False matches ADR-0062;
  • transitive_surface=True, max_depth=1 matches single-chain;
  • transitive_surface=True, max_depth=2 matches ADR-0062 when no second hop exists, strict superset when one does;
  • flags observable on frozen config.
• Null-drop invariant:
  • cognition-lane public + holdout metrics byte-identical transitive_surface OFF vs ON at max_depth=2. The composer is a strict-superset emitter (every token in the depth-1 surface is preserved; new tokens append) so expected_term and expected_surface_contains assertions must hold flag-on.

Lanes (regression check)

core test --suite smoke
core test --suite cognition
core test --suite teaching
core eval cognition

Live-prompt observable lift (expected)

composed_surface=True (ADR-0062):
  "Why does light exist?"
  → light — teaching-grounded (cognition_chains_v1):
    cognition.illumination; logos.core. light reveals truth
    (cognition.truth), which grounds knowledge (cognition.knowledge).
    No session evidence yet.

transitive_surface=True, max_depth=2 (ADR-0083):
  "Why does light exist?"
  → light — teaching-grounded (cognition_chains_v1):
    cognition.illumination; logos.core. light reveals truth
    (cognition.truth), which grounds knowledge (cognition.knowledge),
    which requires evidence (cognition.evidence). No session evidence yet.

The third clause is already in the ratified corpus (knowledge requires evidence). ADR-0083 doesn't introduce content; it surfaces content the realizer was silently dropping.

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Consequences

What changes

• core/config.py — RuntimeConfig.transitive_surface: bool = False, RuntimeConfig.transitive_max_depth: int = 2.
• chat/teaching_grounding.py — teaching_grounded_surface_transitive(subject, intent_tag, *, register, max_depth) sibling to the depth-1 composer; shared follow-up-resolution helper refactored out of ADR-0062's body so both composers consult one function (no behavioural change to the depth-1 path).
• chat/runtime.py — dispatch branch in _maybe_pack_grounded_surface for IntentTag.CAUSE / IntentTag.VERIFICATION picks transitive > composed > single based on the two flags.

What does not change

• The pack-grounded discipline: every visible token remains lemma, pack-domain, connective, or template constant. No LLM. No synthesis.
• ADR-0053's cold-start contract: empty session + no chain → universal disclosure.
• ADR-0062's null-drop invariant: still enforced; ADR-0083 adds its own equivalent at depth-2.
• Default runtime behaviour: byte-identical to pre-ADR-0083 main.
• The non-negotiable field invariant (versor_condition(F) < 1e-6) is unaffected — this ADR composes surface text from ratified chains; no algebra is touched.
• Trust-boundary labels: every emitted surface continues to carry the teaching:{corpus_id} tag.

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Scope limits

• Depth-2 default. v1 ships at max_depth=2. Depth-3 and beyond are reachable by raising the config field, but the default holds until a follow-up ADR characterises lift and readability.
• Single-corpus traversal. Cross-corpus transitive chains (e.g. cognition → relations) are deferred. ADR-0064 already allows cross-corpus single-chain emission; transitive cross-corpus adds an audit surface (teaching:{cognition_chains_v1, relations_chains_v1}) that needs its own ADR.
• No multi-claim aggregation. When a subject has multiple initial chains, the composer still picks one — same selection as ADR-0062.
• English path only. Linker , which and humanize_predicate connectives are English-specific. Anchor-lens lifts of transitive surfaces will need their own per-pack linkers — out of scope.
• Flag stays off by default. Operators must opt in. A follow-up ADR decides on default behaviour after measuring on holdout cases and on the cognition eval.

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Why now (and why not the alternatives)

The three other candidate next-steps:

1. A learned φ embedding (replace hash-derived φ with one trained on chain co-occurrence). Real research, could be wrong, lives in evals/lab/.
2. Greek/Hebrew content phase II (lift the cognition-tier grc/he packs from 9+3 lemmas to ~50+). Content grind, not architecture.
3. Teaching corpus epistemology v2 / kinship v2. Also content grind.

ADR-0083 is the only one that:

• exercises only existing primitives (PropositionGraph, chains, pack-grounded surfaces, the ADR-0062 composer pattern),
• ships behind the established opt-in-flag + null-drop-invariant pattern,
• has measurable lift on the existing holdout corpus without any new content,
• and lands inside one ADR.

It is the smallest design step that moves the substantive ceiling.

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Cross-References

• ADR-0062 — the depth-1 composer this ADR extends.
• ADR-0058 — the opt-in-default-False + null-lift-invariant pattern reused here.
• ADR-0053 — the cognition- lane closure that frames "term_capture is the next ceiling."
• ADR-0064 — defines the cross-corpus chain model that the cross-corpus-traversal scope limit defers to a future ADR.
• Memory: phi separation falsified — establishes that semantic capability lives in chain composition, not in φ geometry, framing why deepening the composer is the load-bearing next step.