diff --git a/corpus/construction-spine/identify-physical-carrier/index.md b/corpus/construction-spine/identify-physical-carrier/index.md
index ba6c2f925..4c51bd4ba 100644
--- a/corpus/construction-spine/identify-physical-carrier/index.md
+++ b/corpus/construction-spine/identify-physical-carrier/index.md
@@ -91,28 +91,141 @@ construction_step_id: "CS-04"
Status note. Build status reflects the current internal state of the Corpus. It does not imply external acceptance unless explicitly stated.
-## What this step is required to do
+## 1. What this step must build
-The program must locate a structure inside the kernel capable of carrying physical semantics: locality, globality, entities, observables, interactions, dynamics, and lawfulness.
+The program must locate a structure inside the kernel capable of carrying physical semantics — locality, globality, entities, observables, interactions, dynamics, and lawfulness — *without* yet making any empirical claim.
-## What the corpus built
+By the end of this step:
-The Corpus identifies the physical-carrier problem through the relevant self-enrichment and unitary construction layer.
+- The **4+1 sector template** must be derived (not assumed) from the kernel's five generators.
+- **Boundary functoriality (Langlands0)** must be shown to *induce* the sector decomposition.
+- The **spectral algebra** must be earned at E0 — the toolkit Books IV–V apply at E1.
+- The **Hinge Theorem** must establish that every result in Books IV–VII is a sector instantiation of Book III's enrichment structure.
+- The **No Knobs Principle** / **No Knobs Ledger** must establish that all inter-sector couplings are determined by `ι_τ` — no free parameters.
+- **Where physics lives**: local bulk projections must glue; the decompactification limit `τ³_R → ℝ³` must recover Euclidean space at human scales; the **3+1 spacetime signature** must be derived from the `τ¹ × T²` fibered product.
+- The **Eight Guarantees** — Spatial, Harmonic, Regular, Discrete, Legible, Codable, Coherent, Predictive — must be earned as the structural force names.
-## What this step builds
+What cannot yet be assumed: time, mass, energy, fields as physical primitives (CS-05); SI units (CS-06); life (CS-07).
-This step turns the Agenda question "where can physics live inside the kernel?" into a Corpus construction problem. It identifies the structural layer that can carry physical roles before measurements or empirical adequacy are discussed.
+## 2. The construction challenge
-## Why this step is required
+This step is hard for five interlocking reasons.
-Physics cannot be assumed as a finished external domain. The Corpus must first explain what kind of internal structure can support physical meaning at all.
+**2.1 Cannot assume spacetime, fields, particles, measurement, or physical law.** The kernel is mathematics (Books I–II). Physics must be *located* inside it without smuggling in physical primitives. The natural temptation — "let τ³ be a topological space" with all the implicit structure that brings — is exactly what must be avoided.
-## Key constructions
+**2.2 Must identify where locality and globality can live.** Local bulk projections must glue into a single, globally coherent three-dimensional space — but the gluing condition itself cannot be assumed; it must be derived as a theorem.
-- The carrier problem.
-- Locality and globality.
-- Entities, observables, and interactions.
-- Dynamics and lawfulness as internal roles.
+**2.3 Must not smuggle in physics as vocabulary.** Naming things "fields" or "particles" before the structure is in place is a category mistake. The 4+1 sector template must be a *consequence* of generator structure under boundary functoriality, not a label applied to a pre-conceived list.
+
+**2.4 Must distinguish carrier identification from physical content.** CS-04 identifies *where physics lives*. The actual physics — constants, laws, particles, cosmology — lives in CS-05 + CS-06. The boundary between "structural carrier" and "physical content" must be sharp; if it blurs, downstream empirical claims have nothing distinct to stand on.
+
+**2.5 Must earn the 3+1 spacetime signature.** The temporal/spatial split is normally postulated. It must be *derived* — from the `τ³ = τ¹ ×_f T²` fibered product structure inherited from Books I–II.
+
+## 3. What Panta Rhei builds
+
+The Corpus builds, at canonical scope, the structural physics layer E1 via four manuscript-grounded constructions: the 4+1 sector template, the spectral algebra, the Hinge Theorem, and the Global Cartesian Gluing of "Where Physics Lives".
+
+Step 4 turns the Agenda question — *where can physics live inside the kernel?* — into a derivation, not a posit. The answer is that the same five generators that determine the τ-kernel determine, by functorial necessity at E1, both the sector decomposition and the spacetime signature. **E1 is not a model of physics — it IS the structural layer where physics becomes definable.**
+
+### The 4+1 Sector Template (Book III Part II)
+
+The five generators of τ — `α`, `π`, `γ`, `η`, `ω` — induce **four primitive sectors plus one mixed sector** (the ω-coupling). The decomposition is *not chosen*: **Langlands0 (boundary functoriality) induces it as a theorem**. The functor from boundary characters to interior holomorphic data preserves sector structure, so the 4+1 form is a functorial consequence.
+
+At enrichment level E1, the template instantiates as:
+
+| Generator | Sector at E₁ |
+|---|---|
+| `α` | Gravity (D-sector) |
+| `π` | Weak (A-sector) |
+| `γ` | Strong / computational |
+| `η` | Electromagnetic |
+| `ω` | Higgs / mass coupling |
+
+Two structural commitments accompany the template:
+
+- **Parity Bridge Theorem** — identifies the **weak sector** as the canonical carrier for the *computational bootstrap* that bridges to Book VI's life recovery.
+- **No Knobs Principle** — establishes that **all sector couplings are determined by `ι_τ`**, not as free parameters.
+
+### Spectral Algebra at E₀ (Book III Part III)
+
+The algebraic vocabulary for everything that follows is earned at E0 — the same algebraic substrate as Books I–II. The spectral toolkit comprises:
+
+- **CRT Decomposition Theorem** — a τ-native Chinese Remainder Theorem via modular Bézout, *without signed arithmetic* — earned-language discipline in action.
+- **Hensel lifting** — performed constructively in residue carriers (III.T11, III.D21).
+- **Primorial ladder** `Prim(k) = p₁ · p₂ ⋯ p_k` — the canonical cofinal filtration unifying finite-level verification across all Millennium Problems.
+- **Spectral trichotomy III.T14** — every boundary character decomposes uniquely into B-supported, C-supported, and X-mixing components.
+- **Computable classifier `Label_n` (III.D23)** — replaces informal lobe language with computable predicates.
+
+### The Hinge Theorem (Book III Part VII)
+
+Part VII assembles the **Complete Dependency Chain** showing the full derivation path:
+
+> five generators → seven axioms → four orbits → ABCD coordinates → boundary ring → Central Theorem (Book II) → enrichment ladder (E0 ⊊ E1 ⊊ E2 ⊊ E3) → 4+1 sector template → spectral algebra → Millennium clusters → enriched bi-square → computational collapse → Hinge.
+
+**Every link is earned; no postulates, no free parameters.**
+
+The **Hinge Theorem (III.T20)** itself states:
+
+> Every result in Books IV–VII is a sector instantiation of Book III's enrichment structure.
+
+The seven-book architecture is **derived, not postulated**. Export contracts to all four downstream books are formalized in Book III Chapter 62. The **No Knobs Ledger** (Book III Chapter 63) exhibits that every inter-sector coupling is canonically determined by `ι_τ`.
+
+### Where Physics Lives — Global Cartesian Gluing (Book III Part VIII)
+
+Local bulk projections glue (III.T21). The **decompactification limit** `τ³_R → ℝ³` recovers Euclidean space at human scales, and the Minkowski extension from the base `τ¹` provides 3+1-dimensional spacetime with the **correct signature**.
+
+The **Eight Guarantees Earned** revisit the gluing requirements with a theorem number and a structural force name attached to each:
+
+- **Spatial** — bulk projections glue locally
+- **Harmonic** — frequency / mode decomposition is internal
+- **Regular** — analytic discipline (τ-holomorphy)
+- **Discrete** — countable address structure
+- **Legible** — `Label_n` classifier is computable
+- **Codable** — sector-level encoding is well-defined
+- **Coherent** — boundary-character coherence holds
+- **Predictive** — closed-form prediction discipline (forward to CS-06)
+
+The **Temporal-Spatial Decomposition** unpacks the base `τ¹` direction as the temporal axis and the fiber `T²` directions as spatial — completing the 3+1 signature derivation.
+
+### E₁ Complete
+
+Book III Chapter 76 synthesizes: **`E_1` is not a model of physics — it IS the structural layer where physics becomes definable**. Export contracts to Books IV–V are formalized; the transition to E2 (life layer, Book VI) is previewed. Book III closes the foundational arc; the τ-effective scope is honoured throughout.
+
+## 4. Why this matches the required answer-shape
+
+Step 4 identifies the physical carrier as a τ-internal derivation, not a presumption. Its admissibility is evaluated against the obligation to locate physics inside the kernel without importing physical primitives.
+
+**Gluing to previous steps.** CS-04 inherits CS-01's kernel + boundary algebra + holomorphy + τ-topos; CS-02's recovered mathematics; CS-03's enrichment ladder + Central Theorem + Categoricity. The 4+1 sector template is the structural reading of the five generators (CS-01 K1) under the Central Theorem's holographic principle (CS-03 II.T40). The spectral algebra at E0 uses the boundary ring + CRT machinery already earned in Book I.
+
+**No-externalities discipline.**
+
+- **No assumed spacetime.** Spacetime emerges from the `τ¹ × T²` fibered product; the 3+1 signature is derived (III.T21).
+- **No assumed fields or particles.** Sectors are functorial consequences; particles, generations, and the constants ledger are CS-05 territory.
+- **No free parameters.** No Knobs Principle / Ledger commits all inter-sector couplings to `ι_τ`.
+- **No imported physics vocabulary.** "Sectors" is the structural vocabulary; "EM/weak/strong/gravity" are *instantiations* at E1, not primitives.
+
+**Earned language.** Every sector is a theorem (III.T03 — Langlands0 induces decomposition). The carrier identification is *earned* via the Eight Guarantees. The 3+1 signature is *derived*.
+
+**Internal standpoint.** The carrier identification is τ-internal. E1 is enriched-over-τ; "physics-as-structural-layer" is a τ-categorical claim, not a meta-physical assertion.
+
+**Step gluing — what later steps does it enable.**
+
+- **CS-05 Recover Internal Physical Grammar** instantiates the 4+1 template at E1: τ-time, τ-mass, τ-fields, τ-laws are defined inside the carrier.
+- **CS-06 Measurement Bridges** uses the No Knobs Ledger to calibrate every dimensionless ratio via `ι_τ` and the neutron-mass anchor `m_n`.
+- **CS-07 Recover Life** uses the **Parity Bridge Theorem**'s computational-bootstrap carrier as the route from physics to life recovery.
+- **CS-08 / CS-09 / CS-10** inherit E1 as the layer above which higher enrichments (E2 life, E3 metaphysics) are constructed.
+
+**Bridge status.** CS-04 is *carrier identification*, not measurement. Bridges to standard physics begin at CS-05 (internal grammar) and consolidate at CS-06 (measurement / SI / prediction). Empirical claims have no place in CS-04 — that boundary is sharp and load-bearing.
+
+**Unresolved boundaries.** CS-04 does not by itself settle:
+
+- Specific physical content — constants, laws, particle content (CS-05 + Book IV).
+- Cosmological structure (CS-05 + Book V).
+- Empirical adequacy of any sector instantiation (CS-06).
+
+These are explicit handoffs, not concealed gaps.
+
+**This is an internal construction claim, not external acceptance.** Step 4 derives the physical carrier under τ-discipline; reviewer scrutiny is invited via Book III's full dependency chain, the No Knobs Ledger, the registry, and the TauLib formalization.
## Registry spine
diff --git a/corpus/construction-spine/measurement-empirical-bridges/index.md b/corpus/construction-spine/measurement-empirical-bridges/index.md
index 4e2374956..0af36d104 100644
--- a/corpus/construction-spine/measurement-empirical-bridges/index.md
+++ b/corpus/construction-spine/measurement-empirical-bridges/index.md
@@ -100,27 +100,115 @@ construction_step_id: "CS-06"
Status note. Build status reflects the current internal state of the Corpus. It does not imply external acceptance unless explicitly stated.
-## What this step is required to do
+## 1. What this step must build
-The program must distinguish what is calibrated, what is predicted, what is dimensionful, what is dimensionless, and what would falsify or pressure the framework.
+The program must build the bridge from internal τ-physics to observed reality. By the end:
-## What the corpus built
+- **Dimensionful constants** must be calibrated via SI translation through `ι_τ` and the **neutron-mass anchor `m_n`**.
+- The full **constants ledger** must surface as rational functions of `ι_τ` — every dimensionless coupling closed-form.
+- **Predictions** must be separated from **fits**: in τ³ there is no renormalization group flow, so constants are *read out*, not *run*.
+- **Falsification paths** must be explicit — named experiments with stated outcomes that would refute specific claims.
+- The numerical physics ledger must be auditable — every entry traceable from `ι_τ + m_n` back to its kernel-internal derivation.
+- Observational support status for cosmological claims must be clearly distinguished from empirically-pending material.
-The Corpus and Verify surfaces expose unit bridge, calibration, constants, dimensionless ratios, predictions, falsification paths, and observational comparison.
+What cannot yet be assumed: life (CS-07); reflection (CS-08); self-hosting (CS-09); ontic closure (CS-10).
-## What this step builds
+## 2. The construction challenge
-This step connects internal tau-physics to measurement, calibration, numerical predictions, observational comparison, and falsification pressure.
+This step is hard for five interlocking reasons.
-## Why this step is required
+**2.1 Dimensionful constants need calibration.** Pure τ-physics has no SI units. To compare with observation, dimensionful quantities (mass, length, time, charge) need a calibration anchor — and that anchor cannot itself be a posit.
-An internally coherent physics can still fail to describe measured reality. The bridge must therefore be inspectable rather than silently assumed.
+**2.2 SI units cannot be primitive.** SI is a measurement convention, not a τ-internal structure. The bridge from τ to SI must be a *theorem*, not a definition. The construction must derive when and why specific SI quantities appear.
-## Key constructions
+**2.3 Predictions must be separated from fits.** Most "successful" constants ledgers in physics are partially fitted. The τ-framework's commitment is **zero free parameters** — every dimensionless ratio is a closed-form function of `ι_τ`. This claim must be auditable, not just asserted.
-- Unit and SI bridge.
-- Calibration and measured constants.
-- Dimensionful and dimensionless prediction surfaces.
+**2.4 Falsification paths must be explicit.** A research program is only as good as its falsification surface. CS-06 must surface named experiments with stated outcomes that would *refute* specific framework claims — not just abstract "could be tested by" gestures.
+
+**2.5 Empirical alignment must not be overclaimed.** Some cosmological claims (Hubble parameter, dark sector) are within current observational uncertainty; others are predictive. The page must not blur the distinction between "matched to within current measurement precision" and "predicted in advance, awaiting future experiment."
+
+## 3. What Panta Rhei builds
+
+The Corpus and Verify surfaces together expose the unit bridge, calibration, constants, dimensionless ratios, predictions, falsification paths, and observational comparison. Step 6 connects internal τ-physics — earned in CS-05 — to measurement, calibration, numerical predictions, and falsification pressure.
+
+The framework's commitment is structural: **one dimensional anchor (`m_n`), one dimensionless constant (`ι_τ`), zero free parameters**, every other entry of the constants ledger derivable in closed form.
+
+### The Constants Ledger and Complexity Summit (Book IV Part VIII)
+
+The book's grand synthesis. Seven chapters draw together every constant, every derivation, every structural theorem developed throughout Book IV:
+
+- **Complete coupling ledger** (Ch65) — ten inter-sector couplings tabulated as **rational functions of a single number `ι_τ`**.
+- **Ontological layer stack** (Ch66) — strict hierarchy: geometry first, spectral theory second, calibration third.
+- **Running-vs-readout distinction** (Ch67) — `τ³` has *no renormalization group flow*. **Constants are read out, not run.** This is the structural reason behind the zero-free-parameter claim.
+- **10-link mass ratio chain** (Ch68) — `R = m_n / m_e` derived from `ι_τ` alone, matching CODATA to **sub-ppm precision**.
+- **Neutron lifetime** (Ch69) — the crown of the calibration cascade; the most complex derived quantity, depending on every earlier derivation.
+- **Laws as structure** (Ch70) — physical laws are not external prescriptions; they are **diagram-level tautologies within τ³**.
+- **The self-describing universe finale** (Ch71) — *One dimensional parameter. Zero free dimensionless constants. The entire microcosm.*
+
+### Cosmic Stack API (Book V Part I, Chapters 8–10)
+
+The cosmological observation interface. Converts τ-internal cosmological structure (refinement-progression epochs; Σ_now hypersurface; orbit-depth Hubble parameter) into observation-ready quantities — distance ladder, boundary data, redshift, large-scale structure. The Cosmic Stack API is the bridge layer between Book V's internal cosmology and observation.
+
+### Astrophysical and Cosmological Readouts (Book V Parts IV–VI)
+
+- **Collective Dynamics** (Part IV) — galaxy rotation curves, gravitational lensing, large-scale structure as collective readouts of the τ-Einstein equation.
+- **Global Structure** (Part V) — cosmic microwave background, primordial power spectrum, tensor-to-scalar ratio.
+- **Eternal Dynamics** (Part VI) — long-time / endgame cosmology; thermal death; asymptotic structure; post-temporal epoch readouts.
+
+### The Decisive Falsification — CMB-S4
+
+The single most leverageable falsification surface: the framework predicts the **CMB-S4 tensor-to-scalar ratio**
+
+> r ≈ ιτ⁴ ≈ **0.0136**
+
+CMB-S4 — the next-generation cosmic-microwave-background experiment, operational around 2030 — will measure r at a precision that **distinguishes this prediction from competing inflationary models**. The framework is committed in advance: if the measured value is materially different, the framework is in serious trouble.
+
+This is what scientific accountability looks like when a program treats falsifiability as a structural feature rather than a defensive afterthought. The full prediction-timing ledger ({% include release-metric.html id="falsifications.records" %} falsification paths through ~2035) lives at [`/verify/predictions-and-falsification/`]({{ '/verify/predictions-and-falsification/' | relative_url }}).
+
+### Falsification ledger — the verify-lane partner
+
+Every prediction is paired with at least one named experiment with a stated refutation outcome. Sample classes:
+
+- **Decisive cosmology** — CMB-S4 r ≈ 0.0136 (~2030).
+- **Particle physics** — masses, mixing angles, fine-structure α to ppm precision.
+- **Gravitational** — Mercury perihelion, light deflection, gravitational waves; gravitational closing identity α_G = α¹⁸·√3·(1−(3/π)α).
+- **Atomic / molecular** — Rydberg, hydrogen spectrum, atomic transitions.
+
+The falsification ledger lives in `/verify/predictions-and-falsification/`; CS-06 is the construction-side surface that makes the ledger possible.
+
+## 4. Why this matches the required answer-shape
+
+Step 6 builds the bridge from τ-internal physics to measured reality. Its admissibility is evaluated against the obligation to make empirical accountability *distinct from* internal semantic physics — sharp boundary, not blurred.
+
+**Gluing.** CS-06 inherits CS-04's No Knobs Ledger (every coupling determined by ι_τ) + CS-05's closed-form constants (α, G, …) + the neutron-mass anchor `m_n` from CS-05's Joint Core. The Cosmic Stack API uses CS-05's time-from-τ¹ and gravity-earned constructions.
+
+**No-externalities.**
+
+- **No SI primitive.** SI is a measurement convention; the bridge is a theorem (Cosmic Stack API; mass-ratio chain), not a definition.
+- **No fitted constants.** The running-vs-readout distinction makes the zero-parameter claim *auditable*, not just asserted.
+- **No hidden empirical fudge.** Every empirical comparison cites the predicted value alongside the measured value. The falsification ledger publishes outcomes that would *refute* specific claims.
+
+**Earned language.** Every constants-ledger entry is *derived* from `ι_τ + m_n`. The 10-link mass ratio chain (`R = m_n/m_e` to sub-ppm) is a closed-form derivation, not a fit.
+
+**Internal standpoint with explicit bridge layer.** The ledger is τ-internal *content*; the SI translation is the *bridge layer*, surfaced explicitly. This separation is what allows reviewers to inspect the construction and the calibration as distinct surfaces.
+
+**Step gluing — what later steps does it enable.**
+
+- **CS-07 Recover Life** uses the calibration discipline as a template: life biomarkers will be calibrated similarly (m_n analogue at the life layer; structural readouts; closed-form ratios where derivable).
+- **CS-08 Reflective Structure** uses the running-vs-readout distinction as the precondition for treating cognition as structural readout, not free phenomenon.
+- **CS-09 / CS-10** inherit the structure-vs-content distinction sharpened here.
+
+**Bridge status — empirical accountability is distinct from internal semantic physics.** This is the briefing's stated admissibility focus for CS-06, and the page honours it: the Cosmic Stack API, the constants ledger, and the falsification ledger together constitute the bridge surface; nothing in CS-04 or CS-05 was claiming empirical adequacy.
+
+**Unresolved boundaries.** CS-06 does not by itself settle:
+
+- **Empirical adequacy** of every prediction — that depends on future experiments (CMB-S4 ~2030; particle-physics tests; cosmological surveys).
+- **Life recovery** (CS-07) — the calibration discipline transfers, but the life layer's content is the next step's burden.
+- **Reflection / self-hosting / ontic closure** (CS-08, CS-09, CS-10).
+
+These are explicit handoffs. The empirical-pending status of falsification claims is published, not concealed.
+
+**This is an internal construction claim, not external acceptance.** Step 6 builds the bridge layer between τ-internal physics and measurement; reviewer scrutiny is invited via the Numerical Physics Ledger, the Falsification Pack, the prediction-timing surface, and the registry. The construction is claimed to be admissible relative to the required answer-shape; empirical adequacy is a separate accountability question, owned by the experiments named in the falsification ledger.
- Falsification paths.
- Observational comparison.
diff --git a/corpus/construction-spine/recover-internal-physical-grammar/index.md b/corpus/construction-spine/recover-internal-physical-grammar/index.md
index 27cbf1364..58473e922 100644
--- a/corpus/construction-spine/recover-internal-physical-grammar/index.md
+++ b/corpus/construction-spine/recover-internal-physical-grammar/index.md
@@ -95,27 +95,151 @@ construction_step_id: "CS-05"
Status note. Build status reflects the current internal state of the Corpus. It does not imply external acceptance unless explicitly stated.
-## What this step is required to do
+## 1. What this step must build
-The program must recover tau-time, tau-space, tau-mass, tau-energy, fields, observables, dynamical laws, and physical regimes as internal structures.
+The program must recover τ-time, τ-space, τ-mass, τ-energy, τ-fields, τ-observables, τ-laws, and physical regimes as **internal structures** before any empirical calibration.
-## What the corpus built
+By the end of this step:
-The Corpus organizes internal physics as a semantic grammar carried by the kernel, distinct from measurement bridge and external empirical validation.
+- Each physical primitive — time, mass, energy, field, law, particle, observable — must be defined as a τ-internal object with τ-internal proofs.
+- **Dimensional and semantic consistency** must hold throughout; every quantity carries a τ-native unit derived from the kernel.
+- Internal physics must be **distinguished from empirical bridge** — a sharp boundary between τ-grammar (CS-05) and SI translation (CS-06).
+- The fiber/microcosm (`T²`, Book IV) and base/macrocosm (`τ¹`, Book V) must each be developed as halves of the same E1 physics, united by the **Hermetic Principle**.
-## What this step builds
+What cannot yet be assumed: SI units, dimensionful constants, measurement, observation, life.
-The fifth step develops internal physical grammar: time, space, mass, energy, fields, observables, laws, and regimes as structures inside the framework.
+## 2. The construction challenge
-## Why this step is required
+This step is hard for five interlocking reasons.
-After the physical carrier is identified, the Corpus must show that the carrier can support something recognizable as physics without merely borrowing standard physical equations as external givens.
+**2.1 Define every physical primitive internally.** Time, mass, energy, field, law, particle, observable each must be a τ-object — not a borrowed concept. The natural temptation is to treat the kernel as "where physics happens" and bring in classical primitives. CS-05 must invert that: the primitives must be earned.
-## Key constructions
+**2.2 Preserve dimensional and semantic consistency.** Every quantity must carry a τ-native unit; no implicit SI assumption. Energy must not be defined in joules, time must not be defined in seconds, until CS-06 makes those bridges explicit.
-- Tau-time and tau-space.
-- Tau-mass and tau-energy.
-- Fields and observables.
+**2.3 Distinguish internal physics from empirical bridge.** The boundary between τ-grammar (CS-05) and SI translation (CS-06) must be sharp. If it blurs, downstream empirical claims have nothing distinct to stand on.
+
+**2.4 Recover physical grammar without SI units.** Internal constants are *structural readouts* of `ι_τ` and the carrier; numerical projection is deferred to CS-06. The fine-structure constant must be derived as `α = (121/225)·ι_τ⁴` *before* it is numerically compared to CODATA.
+
+**2.5 Separate fiber/microcosm from base/macrocosm.** Book IV (microcosm; fiber `T²`) and Book V (macrocosm; base `τ¹`) are distinct halves of the same E1 physics. CS-05 must surface both — and the **Hermetic Principle** must declare their union complete.
+
+## 3. What Panta Rhei builds
+
+The Corpus organizes internal physics as a **semantic grammar carried by the kernel**, distinct from measurement bridge and external empirical validation. Step 5 instantiates the 4+1 sector template at E1 and earns each physical primitive — time, gravity, particles, atoms, thermodynamics — as a τ-internal object.
+
+Two arcs traverse this physics:
+
+- The **Complexity Arc** (Book IV; fiber `T²`) climbs from the neutron through atoms, chemistry, fluids, and computation.
+- The **Force Arc** (Book V; base `τ¹`) descends from gravity through gauge forces and cosmology.
+
+Both arcs share a common root — the Joint Core of Book IV Part I — and both are powered by a single constant: `ι_τ = 2/(π+e)`.
+
+### The Joint Core — vacuum to hydrogen (Book IV Part I)
+
+Ten chapters shared between Books IV and V — the prerequisite for both arcs. Starting from the τ³ arena and the defect-bundle formalism, the Joint Core establishes:
+
+- **Photon** as null transport.
+- **Neutron** as the **minimal stable defect bundle**.
+- **β-decay** produces proton + electron + antineutrino.
+- All five sectors are displayed in concert.
+- **Fine-structure constant** is derived: `α = (121/225) · ι_τ⁴` at **9.8 ppm** precision.
+- **Neutron mass anchors calibration** (structurally identified here; numerical anchor is CS-06 territory).
+- **Hydrogen** closes the sequence as the first composite atom.
+
+The **ontic sequence** is:
+
+> vacuum → neutron → (β⁻) → proton + electron + antineutrino → hydrogen.
+
+Every subsequent chapter in Books IV and V builds on this foundation.
+
+### Quantum Mechanics as Address Obstruction (Book IV Part II)
+
+Quantum mechanics is *not* a separate physical theory imported into τ. It arises as **address obstruction** inside the kernel: the inability to resolve certain compositions to a single canonical address forces the wave-function structure. The τ-framework's QM is therefore τ-internal — derived, not bolted on.
+
+### The four sector arcs at E₁ (Book IV Parts III–VII)
+
+Each sector is a τ-internal *grammar*, not yet calibrated to SI:
+
+- **Electroweak Arc** (Part III) — EM/weak unification as sector readout.
+- **Strong Sector + Confinement** (Part IV) — strong force as the γ-sector arithmetic-mirror reading; the τ-internal QCD analogue.
+- **Particles, Generations, Nuclear** (Part V) — three generations of fermions emerge from sector geometry; nuclear physics readouts.
+- **Atoms, Chemistry, Molecular** (Part VI) — atomic physics as carrier readout.
+- **Condensed Matter + Fluid Dynamics** (Part VII) — bulk matter physics as readout structure.
+
+### Time from τ¹ (Book V Part I)
+
+The base circle `τ¹` carries two generators (`α` Gravity, `π` Weak) and is the source of macroscopic time. Constructions:
+
+- **Proto-time** = ρ-iteration depth (IV.D05); the structural arrow of time (IV.T01).
+- **Proper time** = geodesic arc length along τ¹ (Chapter 4 *Proto-Chronos*).
+- **Time arrow** = α-orbit direction.
+- **Causality** = orbit ordering.
+- **Bounded physical time** = the base circle is compact; time has finite extent at each level.
+- **Three epochs** = pre-temporal, temporal, post-temporal; the **ignition condition** at which proper-time readout becomes well-defined.
+- **Σ_now hypersurface** = structural, not conventional.
+- **Cosmological redshift** = refinement drift.
+- **Hubble parameter** = orbit-depth readout.
+
+When Book V Part I is complete, time, distance, causality, and the initial conditions of the universe have been **derived**, not postulated, from the base τ¹.
+
+### Gravity Earned (Book V Part II)
+
+Gravity is **not** a force that happens to exist; it is the **fourth primitive holonomy sector** of the boundary algebra `H_∂[ω]`, canonically determined by the generator `α` through the Generator–Sector Correspondence.
+
+- **The gravitational constant** `G = (c³/ℏ) · ι_τ²` is **not** a fitted parameter — it is a coherence conversion invariant derived from the torus vacuum shape ratio `r/R = ι_τ`.
+- **The τ-Einstein equation** is **not** a partial differential equation on a background manifold. It is a **boundary-character identity** `R^H = κ_τ · T` expressing curvature and matter as ω-germs in the *same* holonomy algebra.
+- **Lorentz Without Minkowski** (V.T14) — Lorentz covariance is derived as a *theorem about readouts*, not postulated as an axiom about spacetime.
+- The classical `G_μν = (8πG/c⁴) · T_μν` is recovered as the **chart shadow** of the τ-Einstein identity.
+- **Earned linear regime** — Mercury's perihelion, light deflection, gravitational redshift, gravitational waves — all derived as linear readouts of the τ-Einstein identity.
+- **Gravitational closing identity** — `α_G = α¹⁸ · √3 · (1 − (3/π)·α)` ties the gravitational coupling structurally to the fine-structure constant.
+
+When Book V Part II is complete, gravitational dynamics has been **earned**, not postulated, from the base τ¹ and the master constant ι_τ.
+
+### Thermodynamic Inversion (Book V Part III)
+
+What propagates: thermodynamic structure is derived from the base τ¹ rather than postulated. The arrow of time (CS-05 §Time) and the carrier's analytic discipline (CS-04 Eight Guarantees / Harmonic) jointly determine thermodynamic flow.
+
+### The Hermetic Principle
+
+> Fiber `T²` + base `τ¹` together exhaust τ³, and therefore exhaust all E1 physics. When Book V is complete, **nothing physical remains unaccounted for** at the structural carrier layer.
+
+The Hermetic Principle is the closure statement of CS-05's grammar work: the two arcs union to the complete E1 physics layer.
+
+## 4. Why this matches the required answer-shape
+
+Step 5 develops internal physical grammar at the carrier identified in CS-04. Its admissibility is evaluated against the obligation to construct meaningful τ-physics *before* any empirical claim.
+
+**Gluing.** CS-05 inherits CS-04's E1 carrier + 4+1 sector template + spectral algebra + Hinge Theorem + Eight Guarantees. The defect-bundle formalism (Book IV Part I) is the ω-germ machinery (CS-01) instantiated at E1. Time-from-τ¹ uses the base circle of the `τ³ = τ¹ × T²` fibered product (CS-04 Global Cartesian Gluing).
+
+**No-externalities.**
+
+- **No SI primitive.** Internal constants are structural readouts; numerical projection deferred to CS-06.
+- **No imported QM.** QM is τ-internal address obstruction (Book IV Part II).
+- **No imported gravity.** Gravity is the fourth primitive holonomy sector of `H_∂[ω]` (V.T11).
+- **No imported Lorentz.** Lorentz covariance is a readout theorem (V.T14), not an axiom.
+- **No fitted constants.** `α = (121/225)·ι_τ⁴`; `G = (c³/ℏ)·ι_τ²`; `α_G = α¹⁸·√3·(1−(3/π)α)` — all closed-form derivations.
+
+**Earned language.** Every primitive (time, mass, energy, gravity, …) is earned, not borrowed. The τ-Einstein equation is a boundary-character identity, not a postulate.
+
+**Internal standpoint.** All physics-grammar claims are τ-internal. Empirical adequacy is CS-06 territory; CS-05 stops at the carrier-internal level.
+
+**Step gluing — what later steps does it enable.**
+
+- **CS-06 Measurement Bridges** uses the closed-form constants ledger (every dimensionless ratio as a rational function of `ι_τ`); calibrates via the neutron-mass anchor `m_n`; surfaces the running-vs-readout distinction (constants are read out, not run).
+- **CS-07 Recover Life** uses the Joint Core's chemistry/molecular substrate (Book IV Part VI) and the Parity Bridge's computational bootstrap.
+- **CS-09 Self-Host Formal Systems** uses the proof-theoretic mirror over the now-fully-physical E1.
+
+**Bridge status.** CS-05 is *grammar*, not measurement. The classical results (Mercury, light deflection, gravitational waves) are recovered as *chart shadows* of τ-internal identities. Empirical comparison with measured values is CS-06.
+
+**Unresolved boundaries.** CS-05 does not by itself settle:
+
+- SI translation of internal constants (CS-06).
+- Empirical adequacy of any specific physical claim (CS-06).
+- Life recovery (CS-07).
+- Self-hosting or reflection (CS-08, CS-09).
+
+These are explicit handoffs, not concealed gaps.
+
+**This is an internal construction claim, not external acceptance.** Step 5 develops τ-physics as a closed-form internal grammar; reviewer scrutiny is invited via Books IV–V manuscripts, the Joint Core's α derivation, the gravitational closing identity, and the No Knobs Ledger from CS-04. The construction is claimed to be admissible relative to the required answer-shape; it is not claimed to be externally settled.
- Dynamical lawfulness.
- Internal physical regimes.