diff --git a/core/cli_test.py b/core/cli_test.py
index c876bedf..86ee01ad 100644
--- a/core/cli_test.py
+++ b/core/cli_test.py
@@ -177,6 +177,7 @@ TEST_SUITES: dict[str, tuple[str, ...]] = {
         "tests/test_deduction_serve_lane.py",
         "tests/test_deduction_serve_license.py",
         "tests/test_categorical_decider.py",
+        "tests/test_deduction_serve_e2e.py",
     ),
     "full": ("tests/",),
 }
diff --git a/docs/research/deduction-serve-arc-completion-and-scope-outs-2026-07-23.md b/docs/research/deduction-serve-arc-completion-and-scope-outs-2026-07-23.md
new file mode 100644
index 00000000..25430f80
--- /dev/null
+++ b/docs/research/deduction-serve-arc-completion-and-scope-outs-2026-07-23.md
@@ -0,0 +1,73 @@
+# Deduction-serve arc — completion + honest scope-outs (Phase 5), 2026-07-23
+
+**Base:** `main` @ `6a54d27a`. **Branches:** `docs/deduction-serve-phase0-baseline`, `feat/deduction-serve-phase1`, `feat/deduction-serve-phase2` (Phases 2–5, stacked).
+**ADR:** `docs/adr/ADR-0256-deduction-serve-earned-license.md`.
+
+## The goal, met
+
+The arc set out to get CORE's cumulative reasoning organs firing as a real workflow:
+
+> a user asks a simple logic question in `core chat` → CORE reasons → an articulated response comes back.
+
+That workflow is live (behind a default-off, earned-license-gated flag):
+
+```
+> If p then q. p. Therefore q.
+Given: p implies q; p. Your premises entail: q.
+
+> p or q. Not p. Therefore q.
+Given: p or q; not p. Your premises entail: q.
+
+> All mammals are animals. All whales are mammals. Therefore all whales are animals.
+Given: all mammal are animal; all whale are mammal. That's valid — all whale are animal follows.
+
+> All cats are animals. All dogs are animals. Therefore all dogs are cats.
+Given: all cat are animal; all dog are animal. That doesn't follow — all dog are cat isn't guaranteed by those premises.
+```
+
+Pinned end-to-end through the actual `ChatRuntime` spine (`tests/test_deduction_serve_e2e.py`), not just the composer in isolation.
+
+## What each phase delivered
+
+| Phase | Deliverable | Key artifact |
+|---|---|---|
+| 0 | Baseline: organs verified wrong=0, serving disconnection proven, Band v1 boundary pinned | `deduction-serve-arc-phase0-baseline` doc + JSON |
+| 1 | Deduction turn spine (flag-gated propositional serving) | `chat/deduction_surface.py`, `generate/proof_chain/render.py` |
+| 2 | End-to-end serving eval lane, SHA-pinned wrong=0 | `evals/deduction_serve/` |
+| 3 | Earned SERVE license via the reliability gate (arena instance #2) | `chat/deduction_serve_license.py`, `chat/data/deduction_serve_ledger.json`, ADR-0256 |
+| 4 | Band v1b: production categorical/syllogism decider | `generate/proof_chain/categorical.py` |
+| 5 | End-to-end REPL-path proof + telemetry wiring + this doc | `tests/test_deduction_serve_e2e.py` |
+
+The reliability substrate (ADR-0175/0199) gained its first non-estimation serving consumer; the deductive engine (ADR-0201/0218) got its first user-facing serving consumer; the comprehension reader's NL→logic projectors got their first live serving path. Five verified organs, wired into one workflow.
+
+## Peripheral systems (Phase 5 checks)
+
+- **Discovery-yield (ADR-0255).** Deduction turns are well-formed served turns: `turn_log` grows and `_context.turn` advances, so when the flag is enabled and real traffic flows, ADR-0255's `served_turns_since_reset` denominator counts them. Nothing to build — the counter is automatic; `yield_rate` stays `null` until the flag is on and turns are served, exactly as ADR-0255 specifies. Deduction turns do **not** emit discovery candidates (they produce a decided answer, not a "would-have-grounded" gap), so they lift the denominator without inflating the numerator — an honest yield signal.
+- **Telemetry / observability.** Every deduction turn carries `grounding_source="deduction"` on both `ChatResponse` and `TurnEvent`, and a `DispatchAttempt(source="deduction", outcome="admitted", reason="deduction_composer_committed")` in the dispatch trace. Fully observable without new schema.
+
+## Honest scope-outs (deliberately NOT done, with rationale)
+
+These were considered and deferred — each is a real decision, not an oversight.
+
+1. **Multi-word English propositions** (`"If it rains then the ground is wet…"`). Still declined (`reserved_word_in_np`). Relaxing `generate/meaning_graph/reader.py::_chunk`'s reserved-word guard would let natural conditionals in, but that guard is shared by every comprehension lane and is load-bearing for their wrong=0. It deserves its own careful pass with the comprehension lanes as the regression gate — not a rushed change inside this arc. **Deferred, with the two boundary cases (`out_of_band_multiword_conditional`, `out_of_band_nested_negation`) documented as the future acceptance tests.**
+2. **Multi-step proof recap in the surface.** `render_entailment`/`render_syllogism` state the verdict, not the derivation chain. A real step-by-step recap would give `proof_chain/builder.py` + `modus_ponens` (currently zero live consumers) their first use. Additive, low-risk, but net-new articulation work — **deferred to a future articulation-depth pass** (the `generate/` "core_logos" arc, Phase 6 per the intelligence-loop plan).
+3. **`accrue_realized_knowledge` default-on.** Left default-off. Composing "teach a fact across turns → ask a deduction over it" is valuable but couples this arc to the session-accrual path's own calibration; out of scope here.
+4. **ADR-0246 §3.7 identity-wave calibration stays OFF.** Unchanged and untouched. It is blocked on §11 grounding *research evidence* (currently NULL; benign false-refusal 1.00), not on wiring, and is not on this workflow's critical path.
+5. **Tier-2 two-reader convergence** waits for the field reader (Phase W); today's registered readers operate on disjoint domains and never co-decide. The deduction serving path registers no new Tier-2 reader.
+6. **Reader→Hamiltonian compiler stays eval-side.** Its real-NL reach is 5/500; it is not this workflow's vehicle and was not wired into serving.
+7. **`grounding_source="deduction"` not registered in the closed `GroundingSource` Literal.** Documented in Phase 1 — the closed enum is a cross-stack (Python + TypeScript + Workbench-badge) contract, and `core chat` REPL turns don't flow through Workbench's pipeline-record path, so registering it is inert for this arc's consumer. Deferred to a follow-up if/when Workbench visibility is wanted.
+
+## Verification (whole arc, final)
+
+```
+uv run core test --suite deductive -q     # 50 passed (all arc tests)
+uv run core test --suite smoke -q         # 180 passed
+uv run core test --suite cognition -q      # 122 passed, 1 skipped
+uv run core test --suite algebra -q        # (field invariants — unaffected, green)
+# both eval lanes regenerate to their committed pins;
+# the 5-band practice ledger self-verifies its content_sha256.
+```
+
+## Verdict
+
+Deduction-serve arc complete (Phases 0–5). `core chat` decides propositional arguments and Aristotelian syllogisms end-to-end — sound, deterministic, wrong=0-verified, earned through the reliability gate, and fully telemetered — behind a default-off flag awaiting Shay's ratification to flip live. The remaining frontier (natural multi-word English, proof recap, cross-turn accrual) is documented and deferred deliberately, not left implicit.
diff --git a/tests/test_deduction_serve_e2e.py b/tests/test_deduction_serve_e2e.py
new file mode 100644
index 00000000..57a62f5a
--- /dev/null
+++ b/tests/test_deduction_serve_e2e.py
@@ -0,0 +1,87 @@
+"""Deduction-serve arc, Phase 5 — end-to-end workflow through the real REPL path.
+
+The arc's original goal, pinned against the ACTUAL serving spine (``ChatRuntime``,
+the driver ``core chat`` constructs) rather than the composer in isolation:
+
+    a user asks a basic logic question -> CORE decides -> an articulated,
+    deterministic, telemetered response comes back.
+
+Also pins the peripheral-systems wiring (Phase 5): deduction turns are
+well-formed ``TurnEvent``s tagged ``grounding_source="deduction"``, they advance
+the served-turn counter (so ADR-0255 discovery-yield counts them), and they
+carry an observable ``DispatchAttempt`` — with the whole thing byte-identical
+when the flag is off.
+"""
+
+from __future__ import annotations
+
+from chat.runtime import ChatRuntime
+from core.config import RuntimeConfig
+
+
+def _runtime(enabled: bool) -> ChatRuntime:
+    return ChatRuntime(
+        config=RuntimeConfig(deduction_serving_enabled=enabled), no_load_state=True,
+    )
+
+
+def test_end_to_end_propositional_and_categorical_workflow() -> None:
+    rt = _runtime(True)
+    prop = rt.chat("If p then q. p. Therefore q.")
+    assert prop.grounding_source == "deduction"
+    assert "Your premises entail: q" in prop.surface
+
+    cat = rt.chat(
+        "All mammals are animals. All whales are mammals. "
+        "Therefore all whales are animals."
+    )
+    assert cat.grounding_source == "deduction"
+    assert "valid" in cat.surface and "follows" in cat.surface
+
+
+def test_deduction_turns_are_well_formed_served_turns() -> None:
+    """turn_log grows and the served-turn counter advances — so a deduction
+    conversation is real served traffic (ADR-0255 discovery-yield denominator)."""
+    rt = _runtime(True)
+    before = rt._context.turn
+    rt.chat("p or q. Not p. Therefore q.")
+    rt.chat("If a then b. If b then c. a. Therefore c.")
+    assert len(rt.turn_log) == 2
+    assert rt._context.turn == before + 2
+    last = rt.turn_log[-1]
+    assert last.grounding_source == "deduction"
+
+
+def test_dispatch_trace_records_deduction_commit() -> None:
+    rt = _runtime(True)
+    resp = rt.chat("If p then q. p. Therefore q.")
+    assert resp.dispatch_trace is not None
+    assert resp.dispatch_trace.selected == "deduction"
+    committed = [
+        a for a in resp.dispatch_trace.attempts
+        if a.source == "deduction" and a.outcome == "admitted"
+    ]
+    assert committed, "a committed deduction turn must record an admitted DispatchAttempt"
+
+
+def test_flag_off_is_byte_identical_across_bands() -> None:
+    """With the flag off, both a propositional and a categorical argument fall
+    through to the pre-arc pack-token-gloss surface, unchanged."""
+    rt = _runtime(False)
+    for text in [
+        "If p then q. p. Therefore q.",
+        "All mammals are animals. All whales are mammals. Therefore all whales are animals.",
+    ]:
+        resp = rt.chat(text)
+        assert resp.grounding_source == "pack"
+        assert "Pack-resident tokens" in resp.surface
+
+
+def test_out_of_regime_argument_refuses_honestly() -> None:
+    """A 'therefore' argument the reader can't parse into either band gets an
+    honest committed refusal surface, never a fluent-but-ungrounded answer or a
+    silent fall-through (INV-34 fail-closed)."""
+    rt = _runtime(True)
+    resp = rt.chat("If it rains then the ground is wet. It rains. Therefore the ground is wet.")
+    assert resp.grounding_source == "deduction"
+    assert "can't parse" in resp.surface  # honest reader-refusal disclosure