max / pter

Pin the four counterexamples the amplified proptest cell found and lost astra runs this property at 100,000 cases nightly, in a materialized tree that is thrown away. So a counterexample it shrinks lives only in that run's log unless somebody copies the seed into this file, and nobody had: the cell went red on 2026-08-22, 08-25, 08-26 and 08-30 with four distinct shrunk inputs, and passed on 08-31 because the draws happened not to find one again. Three of the four are closed by the fix edge_cases.rs already carries. They stay because they cost nothing and they pin that fix. The fourth still fails, and it is why this file is worth having: <pre/><strong/><h1/><br> </br> -> ```\n**\n\n#\n\n\n**\n``` Empty inline and heading elements outside the fence still emit their own separators, so a triple newline reaches the output. Reproduces in 0.17s with these seeds against the 44,991 draws it took to find. The suite is red until that is fixed, which is the correct state -- the defect predates this commit and was merely invisible.