* grab guide updates from approval-voting branch

* focus on control flow and behavior, not functions

* add approval voting preamble info

* tabs -> spaces

* Companion for #7997

https://github.com/paritytech/substrate/pull/7997



* rename slot_number to slot

* rename SlotNumber type in overseer docs

* "Update Substrate"

Co-authored-by: André Silva <andrerfosilva@gmail.com>
Co-authored-by: parity-processbot <>

* initial impl approval distribution

* initial tests and fixes

* batching seems difficult: different peers have different needs

* bridge: fix test after merge

* some guide updates

* only send assignments to peers who know about the block

* fix a test, add approvals test

* simplify

* do not send assignment to peers for finalized blocks

* guide: protocol input and output

* one more test

* more comments, logs, initial metrics

* fix a typo

* one more thing: early return when reimporting a thing locally

* skeleton

* skeleton aux-schema module

* start approval types

* start aux schema with aux store

* doc

* finish basic types

* start approval types

* doc

* finish basic types

* write out schema types

* add debug and codec impls to approval types

* add debug and codec impls to approval types

also add some key computation

* add debug and codec impls to approval types

* getters for block and candidate entries

* grumbles

* remove unused AssignmentId

* load_decode utility

* implement DB clearing

* function for adding new block entry to aux store

* start `canonicalize` implementation

* more skeleton

* finish implementing canonicalize

* tag TODO

* implement a test AuxStore

* add allow(unused)

* basic loading and deleting test

* block_entry test function

* add a test for `add_block_entry`

* ensure range is exclusive at end

* test clear()

* test that add_block sets children

* add a test for canonicalize

* Update node/core/approval-voting/src/aux_schema/mod.rs

Co-authored-by: Peter Goodspeed-Niklaus <coriolinus@users.noreply.github.com>

* Update node/core/approval-voting/src/aux_schema/tests.rs

Co-authored-by: Peter Goodspeed-Niklaus <coriolinus@users.noreply.github.com>

* Update node/core/approval-voting/src/aux_schema/mod.rs

Co-authored-by: Peter Goodspeed-Niklaus <coriolinus@users.noreply.github.com>

Co-authored-by: Peter Goodspeed-Niklaus <coriolinus@users.noreply.github.com>

* guide: merge backing and approval keys

* bump substrate master & update primitives

* use new SessionInfo struct in session_info

* session keys upgrade for Polkadot

* kusama & westend runtimes

* bump westend, kusama, and polkadot versions

* add session key to rococo & test-runtime

* update prepare-test-net to latest subkey

* update chain specs to support new para_assignment session key

* get cargo.lock from master

* formatting

* update kill_storage based on substrate master

* fix test-service

* assgn -> asgn

* use session info module for assignment session key

* expand description

* basics of availability recovery

* finish availability recovery

* fill out missing text

* Update roadmap/implementers-guide/src/node/availability/availability-recovery.md

Co-authored-by: Fedor Sakharov <fedor.sakharov@gmail.com>

* fix signal handling

Co-authored-by: Fedor Sakharov <fedor.sakharov@gmail.com>

* change approval voting counting procedure

* language

* Update roadmap/implementers-guide/src/node/approval/approval-voting.md

Co-authored-by: Peter Goodspeed-Niklaus <coriolinus@users.noreply.github.com>

* improve language

* time-shifting

* tweak time-shifting

* expand

* typo

* tweaks to ensure we always get woken up

* move timing check into `tranches_to_approve`

Co-authored-by: Peter Goodspeed-Niklaus <coriolinus@users.noreply.github.com>

* skeleton flow control

* tweaks & rename to approvals distribution

* Update roadmap/implementers-guide/src/node/approval/approval-distribution.md

Co-authored-by: Peter Goodspeed-Niklaus <coriolinus@users.noreply.github.com>

* Update roadmap/implementers-guide/src/node/approval/approval-distribution.md

Co-authored-by: Peter Goodspeed-Niklaus <coriolinus@users.noreply.github.com>

* add a `NewBlocks` message and dispatch

* new data format for approval distribution

* guide: update view to include finalized block number

* approvals: document view updating

* pruning when peers disconnect

* add remaining message types

* fix link

* network message type

* handle incoming assignments

* import_and_circulate_approval

* handle new blocks

* address review comments

* address review comments and use nifty VRFProof

Co-authored-by: Peter Goodspeed-Niklaus <coriolinus@users.noreply.github.com>

* elaborate on runtime API

* clarify what to do if the runtime API calls fail

* Update roadmap/implementers-guide/src/node/approval/approval-voting.md

Co-authored-by: Peter Goodspeed-Niklaus <coriolinus@users.noreply.github.com>

* Update roadmap/implementers-guide/src/node/approval/approval-voting.md

Co-authored-by: Peter Goodspeed-Niklaus <coriolinus@users.noreply.github.com>
Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* fix: ensure candidate validation gets code based on occupied core assumption

* guide: runtime API for historical validation code

* add historical runtime API

* integrate into runtime API subsystem

* remove blocked TODO

* fix service build: enable notifications protocol only under real overseer

* Update node/subsystem/src/messages.rs

Co-authored-by: Sergei Shulepov <sergei@parity.io>

* fix compilation

Co-authored-by: Robert Habermeier <robert@Roberts-MacBook-Pro.local>
Co-authored-by: Sergei Shulepov <sergei@parity.io>

* add storage for approvals module

* basics of approval logic

* fix links

* Session info module

* create an approvals_inherent module

* integrate approvals module with inclusion

* Remove approvals runtime

* tweak mentions of on-chain logic

* add note on finality-grandpa voting rule

* elaborate on node-side components

* stub for availability recovery

* add another note on voting rule

* Beginnings of approval subsystems

* flesh out approval voting now

* logic for checking assignment certs

* initial scheduler logic

* scheduler logic

* adjst tranche taking logic

* approval voting import

* approval work (voting side)

* amend some TODOs

* mark some TODOs

* describe `ApprovedAncestor`

* reference protocol-approval.md

* clarity on bitfield

* remove approvals_inherent

* tweak session_info module according to review

* formatting & nits

Co-authored-by: Robert Habermeier <robert@Roberts-MacBook-Pro.local>