% Provenance: corrected synthesis of stages 18--20; stage numbers occur only in this comment. \section[Opposite Twists and Endpoint Chambers] {Opposite Twists, Polynomial Endpoints, and Chamber Approximants} \label{p4:retained:ch:opposite-endpoints} The generic longitude twist has infinite columns in the Newton basis, so it is not an endomorphism of the algebraic direct sum. It nevertheless has row-finite triangular coordinates, an exact generic inverse, polynomial source and target endpoint bases, and integral Hopf-contracted kernels after explicit separable clearing. These facts produce an arbitrary-genus chamber system for standard handles without pretending that one non-Laurent primal lattice is invariant under both twist signs. The one-holed-torus basis and twist conventions are matched to \cite{GilmerMasbaum}, with the graphical normalization fixed by \cite{Costantino}. \subsection{Positive and negative longitude matrices} Retain \[ \Lambda=\mathbb Z[A],\qquad q=A^2,\qquad \FA=\mathbb Q(A), \qquad J_h=q^h(q;q)_h. \] For boundary color $2c$, set \[ Q_n^{\prime(c)}=\frac{Q_n^{(c)}}{\{n\}!},\qquad \{j\}=(-A)^j-(-A)^{-j}. \] The positive and negative Kirby multipliers have coefficients \[ \gamma_k^+= \frac{(-A)^{(k^2+5k)/2}} {\prod_{j=1}^k(A^{2j+1}-1)}, \qquad \gamma_k^-=A^{-3k}\gamma_k^+. \] With \[ C^l_{a,b}=(-1)^l \frac{\{a\}!\{b\}!\{a+b+1\}!} {\{a-l\}!\{b-l\}!\{a+b+1-l\}!\{l\}!}, \] define, for $n\geq m$ and $k=l+n-m$, \[ b_{n,m,l}^{\pm(c)}= C^l_{k,m+c}\frac{\gamma_k^\pm}{\{k\}!} \frac{\{n\}!}{\{m\}!}, \qquad b_{n,m}^{\pm(c)}=\sum_{l=0}^{m+c}b_{n,m,l}^{\pm(c)}. \] Then \[ t_\pm^\star Q_m^{\prime(c)} =\sum_{n=m}^{\infty}b_{n,m}^{\pm(c)}Q_n^{\prime(c)}, \] and the diagonal entries are \[ b_{m,m}^{+(c)}=\mu_{c+m},\qquad b_{m,m}^{-(c)}=\mu_{c+m}^{-1},\qquad \mu_j=(-1)^jA^{j(j+2)}. \] Each coefficient $b_{n,m}^{\pm(c)}$ is a finite sum, but a fixed column has infinitely many rows. These formulas therefore define formal lower-triangular matrices; the next proposition asserts an entrywise inverse identity, not an endomorphism of the algebraic direct sum. \begin{proposition}[Formal inverse identity] \label{p4:retained:prop:c12-inverse} The two infinite lower-triangular matrices $B^+$ and $B^-$ are formal inverses: every matrix-product entry is a finite sum and equals $\delta_{nm}$ in $\FA$. \end{proposition} \begin{proof} The inverse statement is checked entry by entry, rather than by multiplying infinite operators on the direct sum. For fixed source and target indices the triangular shape leaves only finitely many intermediate colors. Root-level inverse twists identify that finite rational expression at infinitely many admissible specializations, which forces the generic identity. For fixed $(n,m)$ the product uses only $m\leq k\leq n$. At every sufficiently large admissible odd level, the chosen lifts are inverse geometric twists, so this finite rational function of $A$ equals $\delta_{nm}$. Equality at infinitely many values of $A$ proves the generic identity. \end{proof} \subsection{Endpoint-local products} The following general lemma explains why row-finite triangular operators act on product completions even when their columns are infinite. \begin{theorem}[Two-sided triangular endpoint products] \label{p4:retained:thm:c12-formal-products} Let $V=\bigoplus_{h\geq0}V_h$, with every $V_h$ finite dimensional, and let $T_{hk}=0$ for $h1$ is odd, write $a=kj+r$ and $b=tj+s$; the remaining residue contribution is \[ k+\left\lfloor\frac{r+s+(j+1)/2}{j}\right\rfloor -\left\lfloor\frac{2r}{j}\right\rfloor -\mathbf1_{r=(j-1)/2}\geq0. \] If $j=2h>2$, write $a=kh+r$ and $b=2ht+s$; the residue contribution is \[ k+\left\lfloor\frac{2r+s+1+h}{2h}\right\rfloor -\left\lfloor\frac{2r}{h}\right\rfloor -\mathbf1_{h\ {\rm odd},\,r=(h-1)/2}\geq0. \] In each case the numerator floor cancels the only possible subtraction when the residue crosses the midpoint; the remaining $k$ is nonnegative. For $j=1,2$ the exponent is exactly $a$. Thus the quotient is a polynomial, its constant coefficient is one, and its $(1-q)$-order is $a$. \end{proof} The theorem cancels every divided local spectator factorial. The remaining possible denominators lie in the trunk factor, the active quantum-dimension factor, and the doubled-tree graph gauge; they are finite in each fixed spectator sector. Let $S\subset\{1,\dots,g\}$ be nonempty, let $\theta$ collect all complementary labels, and unprime the active Newton factors: \[ V^S_{\theta,\mathbf n}= \left(\prod_{i\in S}\{n_i\}!\right)\widetilde b_\lambda. \] For a signed square-free product $T_{S,\delta}=\prod_{i\in S}t_{\delta_i,i}^\star$, higher-genus orthogonality gives \[ B_G(T_{S,\delta}V^S_{\theta,\mathbf m}, V^S_{\vartheta,\mathbf n}) =\delta_{\theta\vartheta}\rho_\theta^S \prod_{i\in S}\mathcal K_{n_i,m_i}^{\delta_i,(a_i)}. \] Here $\rho_\theta^S\in \FA^\times$ is independent of the active indices. Write $\rho_\theta^S=N_\theta^S/Q_\theta^S$ in lowest terms. A \emph{spectator denominator-clearing factor} is a nonzero $D_\theta^S\in\Lambda$ such that $D_\theta^S\rho_\theta^S\in\Lambda$. \begin{proposition}[Lattice of denominator-clearing factors] Every denominator-clearing factor is a multiple of $Q_\theta^S$, and every nonzero multiple is a denominator-clearing factor. Modulo signs, gcd and lcm give a directed distributive lattice with minimum $Q_\theta^S$. Taking the coordinatewise product over sectors preserves these properties. \end{proposition} \begin{proof} The denominator-clearing factor statement is a divisibility calculation in the coefficient UFD. Writing the spectator factor in lowest terms isolates the exact denominator; coprimality forces every denominator-clearing factor to contain it, and multiplication by any extra factor preserves clearing. The gcd/lcm operations and the coordinatewise sector product then give the stated directed lattice. In the UFD $\mathbb Z[A]$, $Q\mid DN$ and $(N,Q)=1$ imply $Q\mid D$. The converse is immediate, and the gcd/lcm claims follow in a UFD. \end{proof} Set \[ \widehat V^{S,D}_{\theta,\mathbf n} =D_\theta^SA^{\sum_{i\in S}R_{a_i}(n_i)} V^S_{\theta,\mathbf n}. \] \begin{theorem}[Integral square-free scalar chamber] \label{p4:retained:thm:c12-scalar} For every sign choice and $\mathbf m\leq\mathbf n$, \[ B_G(T_{S,\delta}\widehat V^{S,D}_{\theta,\mathbf m}, \widehat V^{S,D}_{\theta,\mathbf n}) =D_\theta^S(D_\theta^S\rho_\theta^S) \prod_{i\in S} \left[A^{R_{a_i}(n_i)+R_{a_i}(m_i)} \mathcal K_{n_i,m_i}^{\delta_i,(a_i)}\right] \in\Lambda. \] \end{theorem} \begin{proof} The scalar chamber proof separates spectator denominators from active twist orders. The sector denominator-clearing factor first makes the spectator factor integral, while the uniform local shift makes each active Hopf-contracted kernel polynomial; the product formula then assembles those independent factors over the selected handles. This is a square-free chamber construction, not a claim that one diagonal chart is stable under arbitrary twist powers. The first two factors are polynomial by the definition of a denominator-clearing factor, and each bracketed local factor is polynomial by Corollary~\ref{p4:retained:cor:c12-separable}. \end{proof} For polynomial coefficient families define, on a finite lower ideal $C$, \[ \mathsf G_C= \sum_{(\theta,\mathbf n)\in C} \sum_{\mathbf m\leq\mathbf n} x_{\theta,\mathbf n}y_{\theta,\mathbf m} J_{H_G(\theta,\mathbf n)} B_G(T_{S,\delta}\widehat V_{\theta,\mathbf m}, \widehat V_{\theta,\mathbf n}). \] \begin{theorem}[Arbitrary-genus common scalar approximants] \label{p4:retained:thm:c12-common-net} If $C\subset C'$ and $\nu(C)=\min_{\lambda\notin C}H_G(\lambda)$, then \[ \mathsf G_{C'}-\mathsf G_C\in J_{\nu(C)}\Lambda. \] In particular, the height sequence has increments in $J_N\Lambda$, so the same finite polynomials converge in the disk and cyclotomic branches. \end{theorem} \begin{proof} The common-net estimate is finite before it is completed. A larger lower ideal adds only finitely many outputs and finitely many lower sources, and the height of every new output supplies the corresponding $J$-factor. Consequently the same scalar finite sums are Cauchy in the disk and cyclotomic branches; the conclusion belongs to the common chamber because the construction retains both filtrations. There are finitely many outputs in $C'$, and each has finitely many lower sources. Every newly added output has height at least $\nu(C)$; the exact quotient $J_h/J_{\nu(C)}\in\Lambda$ supplies the divisibility. \end{proof} This scalar chamber and the polynomial endpoint cube are distinct charts. The additional scalar shift satisfies \[ R_c(m)-R_c(n)<0\qquad(n>m), \] and destroys the sharp two-sided endpoint inequality.\newline An endpoint-valuation bridge, not a diagonal identification, is needed to combine them.