Sounds like you've nailed a solid setup there-DG + biochar is genius for those joints, and skipping the geotextile makes total sense on clay since it can wick moisture upward and create ice lenses in freeze cycles. I did something similar but tweaked for my zone 7b clay (also soggy winters), and here's what filled in some gaps for me.
On slope and runoff: That 1-2% pitch toward the rain garden is spot-on for permeability-I've got 1.5% and no pooling. Lateral moisture does wick under the pavers into adjacent beds if your clay isn't fully compacted (aim for 90-95% Proctor density max); I tested it with a soil probe and saw capillary rise up to 12" horizontally. To catch overflow without mulch dams, I cut 1/4" deep v-grooves along the high-edge pavers (using a diamond blade) and lined them with pea gravel-directs sheet flow right to the beds, zero clogging after two years.
Winter de-icers around edibles: Stick to calcium magnesium acetate (CMA) at 1-2 lbs per 1000 sq ft-it's acetate-based so breaks down to CO2 and water, no sodium chloride residue that kills soil microbes or stains pavers. Potassium acetate works too but ferments a bit in wet spots (smelly). Traction sand? It washes away fine in rain gardens but can compact joints if you're not vigilant-use angular granite dust instead, rinses clean and adds to your fines recipe. Never salt near veggies; it'll salinate the soil profile for seasons.
Ants and weeds eco-style: Polymeric cracks open to ant highways eventually anyway (UV and freeze/thaw degrade the binders). My go-to joint mix is 70% 1/8-1/4" crushed granite, 20% composted pine bark fines, 10% corn gluten meal as pre-emergent-stays permeable (tested at 100+ in/hr), ants hate the texture (no tunnels after year 1), and it feeds living joints. Reapply corn gluten in fall; weeds are 90% less without killing beneficials.
Living joints update: Scleranthus rigidus (New Zealand brass buttons) crushes elfin thyme for traffic tolerance-1/2" wide x 2" deep gaps, pre-plant with 1:1 sand/perlite plug mix, and top-dress monthly first summer. Survives chair legs if you shear it back quarterly; foot traffic compacts it tougher.
Oyster shell in joints? Tried it at 20% mix-boosts pH and calcium for slugs (they avoid the sharp edges better than copper tape, which tarnishes and loses charge fast in rain). Noticeable drop in slug trails on my lettuce beds, but source clean, steamed shell to avoid pathogens.
Tree roots/frost heave trick: For shallow ones, excavate a 4-6" "moat" around, fill with 50/50 gravel + expanded shale aggregate (holds air pockets for insulation), then bridge with 4" base layer-no suffocation, heave minimal since shale drains 10x faster than gravel alone. Monitored with stakes; zero shift in three winters.
Mowing strip win: Yes, 6" wide paver ledge cut splash-back 80% (less fungal splash on tomatoes), and slugs congregate there for easy diatomaceous earth patrol. Copper tape? Overhyped-needs perfect contact and oxidizes quick.
Maintenance scales to traffic: Low-use paths need topping every 18 months (1/4" sweep-in), high-traffic quarterly. Re-level with a plate tamper only if settling >1/4"-usually just vibratory plate on fresh fines.
Cross-section sketch if you can visualize: Subgrade (scarified clay) -> 4" 3/4" open gravel -> 2" 1/4" chip -> 1" coarse bedding sand -> pavers -> joints as above. Pics of my root moat DM'd to you-happy digging, and what's your paver size/shape for joint stability?
