Two layers. The enabling layer is the Reglament de participació ciutadana approved by the Plenari del Consell Municipal on 27 May 2022, whose article 37 lets the Ajuntament convene the specific modality of participatory budgets and sets what a convening decree must contain; it permits rather than requires an edition. The operative layer is per edition: mayor Jaume Collboni Cuadrado convened the 2024-2027 process by Decret d'Alcaldia S1/D/2024-00466 of 4 October 2024 under article 13 of the Carta municipal de Barcelona, and the Comissió de Govern approved execution of the 76 voted projects by decree of 19 March 2026, published 27 March 2026. Bindingness is read as binding because the convening decree describes the process as direct democracy and commits in advance to an execution decree, and that decree approves execution in accordance with the citizen vote. The escape clauses matter: the execution decree conditions delivery on unforeseen circumstances not known at technical assessment, and sessions during execution may not change a project's main purpose, use, location or type. The first edition shows the limits in practice: of 76 projects, some were dropped or shrunk by district political decision (Pacifiquem el carrer Rosselló, the five ecoxamfrans on carrer d'Aragó), by law (carrer del Romaninar), by drought restrictions (Fem una Gràcia més verda) or by a new government reassigning a site to social housing (hort urbà al Clot). Scope is themed: only investment projects in three categories, within a district, passing a long list of technical requirements that cut 1,982 proposals to 823 in the first edition. The mandate is renewed edition by edition, so its sunset is the end of each mandate.