Create commentary (including flowchart) about constitution

As the complex flowchart hopefully makes clear, I think the constitution
is more complicated than it might first appear, especially after recent
changes.

This commentary is supposed to make all this explicit.

Author: Ericson2314

.github/CODEOWNERS

@@ -28,6 +28,7 @@
 /doc/values.md @NixOS/steering
 /doc/vault.md @Mic92 @mweinelt @zimbatm
 /doc/constitution.md @NixOS/steering
+/doc/constitution-commentary.md @NixOS/steering
 /doc/nixpkgs-core.md @NixOS/nixpkgs-core
 /doc/nixpkgs-committers.md @NickCao @jtojnar @winterqt @NixOS/nixpkgs-core
 /doc/calendar.md @edolstra @tomberek @fricklerhandwerk

doc/constitution-commentary.md

@@ -0,0 +1,76 @@
+# Constitution Commentary
+
+This document contains a non-normative, non-binding commentary on the constitution, explaining some subtleties.
+
+## SC Election, Removal, and Dissolution procedure
+
+The state machine of these portions of the constitution is especially complex.
+
+These interactions are of special note:
+
+- When less than half of the seats are filled, if any SC member proposes a no confidence vote, the vote will automatically win due to how vacant seats are counted for dissolution votes.
+  However if the SC does not hold such vote, and is thus unanimous in choosing to hold a special election for the currently-vacant seats only instead, such a special election will proceed.
+
+- It is only possible to follow a dissolution with an initial election when more than half of the SC seats were full prior to dissolution.
+
+- Vacant seats not triggering a dissolution vote makes it possible for the vacancy procedure for when less than half of the seats are filled to resolve the situation without dissolution.
+
+- After a removal has occurred, it is possible to hold a special election to fill the vacant seat.
+
+The following flow chart diagrams the procedure, hopfully making these interactions explicit:
+
+```mermaid
+flowchart TD
+    Start([Regular SC Governance])
+    End(["Regular SC Governance (with new members)"])
+
+    %% Note that order effects layout, at least informally.
+    %% Current layout chosen in part because graph renders planar (no edges cross).
+
+    %% Regular elections
+    RegularElec[Regular Election]
+
+    Start -->|some terms end| HalfVacation[[3-4 seats to be vacated]] --> RegularElec
+    RegularElec -->|seats filled for fresh 2-year terms| End
+
+    %% Special Elections
+    SpecialElec[Special Election]
+
+    Start -.->|optional, if <7 filled| SpecialElec
+    SpecialElec -->|winners serve remainder of terms| End
+
+    %% Single seat vacation
+    Removal[Vote for removal for conduct]
+    OneMoreVacation[[one additional seat vacated immediately]]
+    Required[Vote for Special Election or dissolution]
+    AllVacated0[[all seats to be vacated]]
+
+    Start -.->|optional| Removal
+    Start -.->|resignation or other loss| OneMoreVacation
+    Removal -->|succeeds by supermajority| OneMoreVacation
+    OneMoreVacation --> VacancyCheck
+    Removal -->|fails| Start
+    VacancyCheck{Vacancy count?}
+    VacancyCheck -->|≥4 filled| Start
+    VacancyCheck -->|<4 filled| Required
+    Required -->|all members propose special election| SpecialElec
+    Required -->|any member proposition dissolution| AllVacated0
+    AllVacated0 -->|special election wins via vacant seat votes| SpecialElec
+
+    %% Dissolution
+    Dissolution[Vote to dissolve the SC<br/>vacant seats vote yes]
+    AllVacated1[[all seats to be vacated]]
+    ElectionType[Vote between election types<br/>vacant seats vote special]
+
+    Start -.->|optional| Dissolution
+    Dissolution -->|succeeds by majority| AllVacated1
+    AllVacated1 --> ElectionType
+    Dissolution -->|fails| Start
+    ElectionType -->|initial wins| InitialElec
+    ElectionType -->|special wins| SpecialElec
+
+    %% Initial Elections
+    InitialElec[Initial Election]
+
+    InitialElec -->|Entirely new SC seated</br>top 4: 2yr terms<br/>bottom 3: 1yr terms| End
+```