kernel: delete the kernel call log; the per-call chain is the mcp plane's chained kind (row 156)

[MattJackson]

Closes /status row 156: "D4 residue: calllog move to the mcp plane".

Governing lines

• BUSBAR-1.6.0.md Part 3 §4, SUPERSEDED 2026-09-28: "A plane's journal writes are on_piece record writes; a chained record kind keeps its declared framing (§5), now a per-record-kind declaration in the plane's tail, so deployed chains still verify."
• Appendix B.10: "a per-record-kind chain framing list in the tail ... so the host reproduces Part 3 §5's three framings".
• host_chains.rs header, OWNER RULING RULE-CHECK 2026-09-30: "the call log MOVES to the mcp plane over the generic journal append".

State on predev: the mcp plane already writes its call log as a chained record kind (door.rs RECORD_CHAINS: LengthPrefixed, scope in the digest). The host's generic journal appends and resumes it (host_chains). Nothing in production called the kernel's own call log.

What changes

• Deleted:
  • busbar-kernel/src/calllog.rs, plane/calllog.rs and tests/calllog_tests.rs.
  • PlaneBootCtx::register_call_stream / restore_call_log and RestoredSummary, plus the empty impls in the legacy a2a and voice test doubles.
  • The engine kit's four call-log hooks.
  • The plane_host journal helpers only the call log used.
• The frozen per-call boot golden is kept. It now restores the frozen bytes through the generic journal under the mcp plane's declared framing, which is the path the live chain resumes through, and it passes byte-identically.
• BUSBAR-2042, 2045, 7092 and 7093 are retired with their numbers kept and the docs regenerated. A chained kind that does not verify from its tail reports BUSBAR-2048.
• qa/one-memory-abi.toml drops the deleted file's finding.

Behaviour: identical. The deleted code had no production caller.

Measured

• Lines: +114 / -2980.
• D2 files (row-82 filter with plane/): 38 on predev, 37 here.
• abi/hot and abi/cold: unchanged (row 84).
• On the M3 VM: cargo clippy --workspace --all-targets -D warnings passes. cargo test -p busbar-kernel --lib audit:: residual_log host_chains diagnostics plane::: 234 passed, including per_call_chain_boot_verifies_from_frozen_bytes. Catalogue docs were regenerated: 4 passed.

Conflicts: this touches diagnostics/mod.rs, docs/diagnostics.* and qa/one-memory-abi.toml, as #798 (row 157) does. Whichever lands second gets rebased and its docs regenerated.

[github-actions]

promote into predev: all green @e06b815a2

Already red on predev, not this PR's: 16

gate	row	detail
test:xtask-selftest	::xtask selftest kind-isolation
test:xtask-selftest	::xtask selftest teller-steps
test:xtask-selftest	::xtask selftest plane-purity
test:xtask-selftest	::xtask selftest no-deferral-strict-done
test:xtask-selftest	::xtask selftest plane-purity-strict
test:xtask-selftest	::xtask selftest unconstructed
test:xtask-selftest	::xtask selftest structure-lint
test:xtask-selftest	::xtask selftest plane-transport-neutrality
construction	one-pick-site	3 production call site(s) of 'pick_among(' (ceiling 2): crates/busbar-kernel-egress/src/walk.rs:358; crates/busbar-llm/src/engine/exhaustion/fallback.rs:120; crates/busbar-llm/src/engine/pipeline.rs:8
kind-isolation	kind-isolation:deps	3 finding(s), 93 shipped edge instance(s) over 30 class(es), 93 declaration(s); 56 '[[dep]]' row(s), 0 question(s): unlisted-dep-edge legacy -> plane busbar-llm -> busbar-plane-llm is a shipped edge w
kind-isolation-ship	kind-isolation:deps	9 finding(s) over 93 shipped edge(s): ship-edge kernel -> hooks busbar-kernel -> busbar-hook-ranking is 'not-allowed': the architecture grants no kernel -> hooks edge, and the ship criterion is the ar
kind-isolation-ship	kind-isolation:test-deps	5 finding(s) over 31 test edge(s): ship-edge cleanliness -> export busbar-core-admin -> busbar-export-prometheus is 'not-allowed': the architecture grants no cleanliness -> export edge, and the ship c
kind-isolation-ship	kind-isolation:faces	2 finding(s) over 40 crate(s): foreign-entry crates/busbar busbar is kind 'root' and implements 'Transport' 1 time(s) in shipped source — the entry face of kind 'transport'. A trait implementation is
kind-isolation-ship	kind-isolation:legacy-drain	3 finding(s): transitional-live qa/kind-isolation.toml 'busbar-a2a -> busbar-core-admin' (legacy drain: the retiring A2A engine's tests drive the admin surface that drained into the cleanliness tier)
ship-ready	ship-ready:ship-twin	'kind-isolation-ship' is not green: kind-isolation:deps (a dependency the architecture does not grant is still in the graph); kind-isolation:test-deps (a dependency the architecture does not grant is
structure-lint	structure-lint:plane-dup:unledgered	22 finding(s): PLANE-DUPLICATE (module): 'config.rs' — a2a:crates/busbar-a2a/src/a2a/config.rs decisions:crates/busbar-plane-decisions/src/config.rs voice:crates/busbar-voice/src/config.rs (the ledger

tests passed: 19041, failed: 0. Run: https://github.com/GetBusbar/busbar/actions/runs/38346014073 . Artifact verdict-e06b815a288abf82f0a2f1ecd8a6ec17add8c08c (failures.json, junit.xml, raw.log; 90 days).