Timeline

The horizon draft re-pinned to zit horizon-rfc 24457c7dd6, the batch agreed with zit's author: the list-form merge-base query (at most two secondaries; silence when a named check-in is unknown), must-ask when either ancestry crosses the horizon, deepen refusing without a common ancestor, boundary labels over every held manifest, the seed's date and label, the structural fallback dropping the seed, and cursors voided when the leaves rule's held set grows below them. check-in: c216f38b6a user: [email protected] tags: feat/horizon-cones, trunk

Record what the re-pin changed in behavior: the list-form merge-base query and when a merge asks it, the seed's U label, the deepen refusal's remedy, and the cursor voided by a leaves-rule fork. check-in: bb5fc8ebff user: [email protected] tags: feat/horizon-cones, trunk

The re-pinned draft makes the parents of a held baseline below C boundary hashes (5.3, 6.2.2) and states the structural store's fallback for a pull or sync (6.2.5, 6.3). go-libfossil already met both; these cases check them against the final text.

A case on the delta-baseline fixture (c3 and c4 delta manifests on c2, C = c3) checks that c1, the baseline's parent, is labelled no later than the reply delivering c2 and is held as an elided phantom the clone never asks for. An interop test runs the fallback with zit both ways: zit's structural store pulls from go-libfossil serving as a horizon-ignorant peer, and go-libfossil's pulls from a zit that cannot place C; each falls back to the content horizon, discards its seed and fetches the manifests below C. The recording origin gains an ignorant mode for it. check-in: a553cc1e11 user: [email protected] tags: feat/horizon-cones, trunk

Under the leaves rule a new childless check-in forked below C can move the meeting point of its ancestry with C's deeper, and older check-ins join K together with their blobs. Those sit below every cursor the origin had handed out, so a client holding one was never told of them: the origin recorded a reclassification only when a phantom was filled (6.2.6 requires recording any change of the classification).

The origin now also voids a cursor when K holds a check-in at or below it that the held set computed over the check-ins it held through that cursor lacked (horizon.Graph.JoinedAfter, a walk bounded by rid). Like the slot walk's void it is a function of the store, so the memo and a fresh classification agree: TestHorizonMemoEqualsFresh compares them at every cursor and now requires some world to void this way, and a cursor conformance case pulls under the leaves rule across such a fork, the stale cursor answered as if absent once and the next one honoured. check-in: 2c0329ede4 user: [email protected] tags: feat/horizon-cones, trunk

The re-pinned draft's 5.8 has a deepen that finds no common ancestor of C and its target, here or at the origin, refuse and name the remedy, a fresh clone with an earlier horizon, and never move C to a check-in that is not its ancestor. Deepen already refused with ErrNoDeepenPoint and left C and the seed in place, but its message named no remedy; it now does. A conformance case covers both refusals (the origin answers -, and the origin does not answer) and checks that C, the seed and the derived state stay as they were. check-in: 7a2c0b3bc3 user: [email protected] tags: feat/horizon-cones, trunk

The re-pinned draft's 6.2.4 query is a primary and one or two secondaries, `pragma horizon-mergebase <primary> <secondary>...`, and the answer repeats the query in order and appends Fossil's pivot over the set. A two-hash query was answered as the base of a pair, so a merge into a checkout with a merge already pending could be told a base Fossil's merge would not choose. The origin now takes the list (sync.MergeBaseQuery), answers nothing when it lacks any named check-in or is asked more secondaries than a six-token card can repeat, and the client takes only an answer that repeats its query.

5.5 now has the clone ask whenever either side's ancestry crosses the horizon, not only when its own walk does: over part of the graph the common ancestor found need not be the nearest. MergeContext, given a peer, checks the ancestry of the merged-in version, the checkout and its pending plain merges (content.AncestryCrosses), asks the pivot of the merged-in version over the checkout and those merges, and merges over the answer, falling back to Merge when the origin does not answer, as zit's merge does. With two merges already pending the query cannot carry them, and asking without them would name another base, so the merge is refused before anything changes.

The deepen point's query names the target over C, as zit asks it. check-in: 78483726d9 user: [email protected] tags: feat/horizon-cones, trunk

The re-pinned draft (5.2.2) makes a seed's U card the origin's own label for the minting implementation, as zit writes zit-serve, never a user's login: a seed is a tag application no user made. The origin wrote the role name "origin"; it now writes "go-libfossil".

The seed-date case is restated to the final text: D is the latest summarized tag event rounded up to a whole second and written with no fraction, checked with an event a quarter second past the second, and the dropped clause (D strictly later than the seed replaced) is no longer asserted. The structural fallback case moves to the new 6.3 row for a store already at the structural horizon. check-in: fe7d47778e user: [email protected] tags: feat/horizon-cones, trunk

zit's horizon-rfc check-in 24457c7dd6 revises the horizon draft; the other six drafts are byte-identical at it and at 3a2df62515. Each change has its own Appendix C bullet: the seed's D card is the latest summarized tag event rounded up to a whole second with no fraction, its U card the origin's label for the minting implementation, and the strictly-later clause is dropped (5.2.2); a merge asks the origin whenever either side's ancestry crosses the horizon (5.5); a deepen with no known common ancestor of C and the target is refused naming the remedy (5.8); the merge-base query takes a list of secondaries (6.2.4); a boundary hash is a parent of any held manifest, a baseline below C included (5.3, 6.2.2); and a store already at the structural horizon falls back to the content horizon, discarding its seed, when its replies lack horizon-served structural (6.3). The 3.4 cost note changes no rule.

Restate the rows whose text changed (5.2.1, 5.2.2, 5.3, 5.6, 6.2.2, 6.2.3, 6.2.4, 6.3) and add rows for the new statements (5.3, 5.5, 5.8, 6.2.4, 6.3), so each is checked against the final text. check-in: 9a0f07fe70 user: [email protected] tags: feat/horizon-cones, trunk

The horizon draft re-pinned to zit horizon-rfc 3a2df62515, and its new rule: under either horizon a path cone elides the sub-manifest nodes no in-cone slot reaches, and an origin withholds them. Interoperates with zit at 3a2df62515 both ways. check-in: 113123abae user: [email protected] tags: feat/horizon-cones, trunk

Under either horizon with path members an origin now sends only the sub-manifest nodes on paths into the cone of the trees its horizon keeps (every check-in's at the content depth, K's at the structural one), announces none of the rest and answers no gimme for them; a request without path members still receives every node (draft-fossil-horizon-00 §6.2 at zit 3a2df62515).

The walk is zit's walkSlots (src/sparse.zig): only slots that may hold an in-cone path are descended, a last slot takes its parent's bound, and a node is walked again only under a wider bound. It runs over the classification's facts, never the store, and the origin's memo keeps it by cone so a later request walks only the roots appended since, falling back to a fresh walk when a root arrives below the ones walked. A clone round sends nodes by the per-check-in tree walk it already uses without a horizon, walking a check-in outside the held set for its nodes alone.

Each kept node records the lowest root that keeps it, so a cursor is void (§6.2.6) exactly when some node at or below it is kept only by a root above it: stateless, and the same for a fresh classification and the memo, where zit voids every cursor below the store count at the moment its sidecar sees the change.

The memo returned a cone's earlier classification whenever no fact list grew, keeping that store's names, so an artifact appended or filled without becoming a record read as unnamed; it now carries the current facts. Found by the memo equivalence test, which now covers path cones under both horizons, the slot walk, cursor voiding and a tree form that widens a node's bound. check-in: 0de31d6f8e user: [email protected] tags: feat/horizon-cones, trunk

draft-fossil-horizon-00 at zit 3a2df62515 has a path cone elide sub-manifest nodes under either horizon, as the sparse store does (§3.2, §4.1). A content-horizon store held every node of every age, so classification kept a phantom node no in-cone slot reaches as transit and the store kept asking for it. Such a node is now elided, below the horizon too; a node on a path into the cone stays wanted at every age, and a horizon without path members still wants every node.

With nodes elided, a check-in's tree is read by the sparse readiness check before its spine is linked, and that check waited on every covered file. Under a horizon a covered file may lie below it, and which do is placed over the very check-ins the check gates, so a check-in below the horizon was never linked and the derivation lost it. Under a horizon the check no longer waits on files: the spine it publishes reads none, and the classification at rest tells an elided file from a transit one. check-in: 63d67666cd user: [email protected] tags: feat/horizon-cones, trunk

zit's horizon-rfc check-in 3a2df62515 changes one rule of the horizon draft: a path cone now elides sub-manifest nodes under either horizon, as the sparse store does. Of the trees the horizon keeps (every check-in's under a content horizon) only the nodes on paths into the cone are held, an origin withholds the rest, its walk is bounded and kept like the classification, and a cursor is voided when an appended tree makes an older withheld node kept. The other six drafts are byte-identical at both check-ins.

Restate the rows whose text changed (3.2, 4.1, 5.1, 6.2.6), add rows for the new statements (4.1, 4.3, 6.2), and mark the restated rows the code does not meet yet rather than leave them claiming coverage. check-in: bd80910304 user: [email protected] tags: feat/horizon-cones, trunk

A structural clone holds the manifests of the held set and everything they reach through B and S cards (draft-fossil-horizon-00 §5.1), so a delta manifest's baseline below C is held. Its parents were labelled by nobody: boundaryOf took the parents of K's check-ins only. The clone then classified such a parent as transit and requested it, and the origin, which withholds manifests below C, never sent it; the clone stalled with one phantom outstanding. zit's origin has the same gap (sparse.zig 758-783), and zit's author agreed the draft will define a boundary hash as an unheld parent of any manifest the clone holds. boundaryOf now labels the parents of K and of every check-in the reach holds.

The regression is the HZ-3.1-4 case for a delta manifest in K whose baseline lies below C: the clone completes, the baseline is held but not a leaf, and K's check-ins derive the dense repository's tags. check-in: f0354673e2 user: [email protected] tags: feat/horizon-cones, trunk

The origin's classification memo (draft-fossil-horizon-00 §6.2): the reference graph and each cone's classification kept per store prefix and extended by appended artifacts, recomputed in full only when an arrival was already cited. A pull after a one-artifact push on fossil-scm.org's repository answers in about 0.25 s instead of 2.7 to 4.5 s. check-in: 7dec3e4fb3 user: [email protected] tags: feat/horizon-cones, trunk

HZ-3.1-2: the leaves rule's cost is stated where it is chosen. HZ-3.4-2: a horizon reaches the wire only as a full hash and a rule name. check-in: c79a113e0c user: [email protected] tags: feat/horizon-cones, trunk