This preprint develops a Quantum Measurement Units (QMU) research program for Aether displacement waves: longitudinal compression/rarefaction events of the Aether substrate that propagate at the Aether Physics Model (APM) velocity primitive and can couple into tightly organized magnetic structures. Core contributions. 1. Exact QMU dimensional closure for the displacement-field primitive.The displacement field unit is defined as $dfld := 1/(m_e\,F_q)$, so its QMU dimensional structure is $[dfld] = m_e^{-1}F_q^{-1}$. The paper records ledger identities linking $dfld$ to mass-inverse and volumetric receptivity primitives. 2. A displacement-wave observable aligned to longitudinal-wave bookkeeping.Using the mixed-derivative operator $S := \partial_t\partial_x$, we define the normalized displacement mixed-derivative observable $sclw_d^* := (1/F_q)\,\partial_t\partial_x\xi = \partial_{t^*}\partial_{x^*}\xi^*$, where $t^* = F_q t$ and $x^* = x/\lambda_C$. This provides a direct bridge from pulse-domain longitudinal technology to a displacement-wave channel. 3. A QMU-clean coupling mechanism for magnetic-loop destabilization (Gate D1).A leading-order interaction density between displacement and magnetic stress is specified in ledger form: $U_{\mathrm{int}} := pres\,\Gamma_d\,\xi^*\,p_B^*$, where $pres$ is the QMU pressure scale (energy density) $pres := energy/volume = m_e F_q^2/\lambda_C$, $\Gamma_d$ is a dimensionless coupling constant, and $p_B^*$ is a dimensionless magnetic-stress proxy. This yields a stress-gradient forcing proxy $f_{\parallel}=-(pres/\lambda_C)\,\partial_{x^*}(\Gamma_d\xi^*p_B^*)$. A mixed-derivative alternative, $\delta p_B^* = \Lambda_d\,sclw_d^*$, is also provided to make the predicted signature directly gate-computable. 4. Gate suite spanning laboratory and astrophysical tests.The paper states falsifiable gates for: (i) flare triggering via coherent, propagating mixed-derivative precursors (Gate D1), (ii) precursor multiplicity and timing conditioning for supernova/GRB initiation (Gate D2--D3), and (iii) laboratory Aether Displacement Transducer (ADT) tests under fixed per-pulse energy budgets with geometry-defined gradients and channel-suppression controls (Gate D4--D5). 5. SDO/AIA-ready proxy observable for Gate D1.For imaging time--distance tracks along a traced loop coordinate $s$, we define a mixed-derivative intensity proxy $S_{\lambda}(s^*,t^*) := \partial_{t^*}\partial_{s^*}\ln I_{\lambda}(s,t)$ with $s^* = s/\lambda_C$ as an observational analog of $sclw_d^*$. This enables direct searches for coherent propagating precursors prior to impulsive reconnection onset, using Solar Dynamics Observatory / Atmospheric Imaging Assembly (SDO/AIA) data products and standard event-detection pipelines. The paper is written to remain ledger-consistent and QMU-native throughout (no auxiliary base units are introduced). The objective is to provide a reproducible, quantitative path---via explicit observables and falsifiable gates---to test whether a distinct longitudinal displacement channel exists and whether it couples into magnetic instabilities in engineered fixtures and in stellar coronae.