Create commentary (including flowchart) about constitution

.github/CODEOWNERS

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 /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

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+# Constitution Commentary
+
+This document contains a non-normative, non-binding commentary on the constitution, explaining some subtleties.
+
+## SC Election and Removal procedure
+
+The state machine of the portions of the constitution that govern the composition of the SC (what seats are filled, who is in which seat) is especially complex.
+The following flow chart diagrams this state machine:
+
+```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 proposes 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
+```
+
+### Deferred versus immediate loss of members
+
+A no-confidence vote does not immediately dissolve the SC.
+It just triggers the election (which presumably cannot be cancelled) at which point all current SC members loose their seats (unless reelected).
+By contrast, removal for conduct does immediately remove an SC member.
+
+Voluntary resignations are a grey area.
+In the above diagram they are also diagrammed as immediately taking effect, but arguably they could also be deferred until the election when those seats are replaced.
+
+The important part of this distinction is who is a member voting in subsequent votes.
+Members removed for conduct do not vote choose the election type (in the no-confidence case) or whether to hold a special election (in the seats-vacated case).
+Members not resigning absolutely do vote in both those cases.
+Voluntarily-resigning members are a grey area.
+
+### When the SC drops before 4 members
+
+The most subtle part is what happens when the SC drops below 4 members due to "resignation or other less" or removal for conduct.
+
+The constitution states that when less than half of the seats are filled, a special election must occur.
+But, presumably, a vote of no-confidence, triggering a full reelection can occur at any time.
+Therefore, that can also occur instead at this point, leading indeed to a special election also, but a different sort of special election.
+
+If any SC member proposes a no-confidence vote, the vote will automatically win due to how vacant seats are counted for such votes.
+The vacant seats will also automatically cause special election, rather than initial election, to win the subsequent vote for the type of full reelection.
+However, vacant seats do not trigger votes, they only vote once a sitting member triggers a vote.
+Therefore at this point, no attempt to hold a no confidence vote will end in a special election of just the currently-vacant seats, while any attempt to hold a no-confidence vote will end in a special election for all seats.
+
+Note that both paths above lead to a special election.
+As a corollary, it is only possible to follow no-confidence with an initial election when more than half of the SC seats were full prior to the no-confidence vote.