* content: add delta-chain depth benchmark for #85 re-measurement

BenchmarkExpandOldestVersion expands the oldest version of a ~26 KB, 400-line file at 12/50/200 revisions, mirroring the table in #85. The chain is built through content.Deltify so the on-disk shape matches what content_deltify produces: newest version whole, each older version a delta against the one newer.

Reports ns/op plus B/op and allocs/op so the per-link allocation profile the issue is about is directly observable.

* content: straddle delta.Apply's 64 KiB cap in the chain-depth benchmark

BenchmarkExpandOldestVersion measured a ~26 KB file, which sits below delta.Apply's deltaInitialCap: for targets that small the output buffer is allocated at exactly targetLen and the capped/growOutputCap path is never entered, so the arm cannot observe #81/#82 at all.

Parameterise the chain builder on file size and add a ~206 KB arm above the cap, so the two arms isolate the threshold rather than leaving it inferred from reading delta.go. Also move the chain-depth metric after the loop -- ResetTimer deletes user-reported metrics, so the depth reported before it never reached the output.

Refs #85

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Co-authored-by: Dan Mestas <[email protected]> check-in: c3338c4d38 user: [email protected] tags: trunk

The clone command hardcoded a 10-minute context deadline with no way to raise or disable it, and the deadline did not reliably interrupt a slow clone.

- RepoCloneCmd gains a --timeout flag (default 10m, matching the old behavior; 0 disables the deadline for very large repositories). cloneContext branches away from context.WithTimeout for a non-positive timeout -- WithTimeout(parent, 0) yields an already-expired deadline, which would abort instantly the very clone the flag exists to unbound.

- The whole-repository crosslink sweep now observes context cancellation. It runs after the exchange-round loop, so it had no round boundary of its own at which the deadline could fire -- on a large repository it could run long past the deadline uninterrupted. manifest.CrosslinkContext checks the context every 256 candidates; manifest.Crosslink stays a background-context wrapper so its ~30 existing callers are unchanged. processResponse gains the same batched check so a large single-round batch is interruptible too, and the sync session's and the serve handler's post-convergence sweeps are wired to their contexts for the same reason.

Each cancellation point is pinned by a test that fails without it: the crosslink and processResponse tests drive a context that survives the first poll and dies before the second, so only the batched check can observe it; the crosslink-sweep test cancels after a zero-card final round, so nothing before the sweep is left to notice.

Also adds a clone -> serve -> reclone fidelity regression guard (#114), built with the canonical fossil binary rather than this library's Commit. Commit does not deltify, so a corpus built through it holds zero delta rows and never reaches the serve side's deltified-row expansion branch -- a green result from such a corpus proves nothing about #114. The guard now asserts the source holds delta rows before measuring anything, and compares the second-generation clone's tip, artifact count, blob-store size, delta-row count and checked-out tree content against the source.

Measured against that corpus (71 artifacts, 54 delta rows), #114 does not reproduce: gen1 and gen2 both hold the same 54 delta rows, the same tip and artifact count, a 1.009 store ratio, identical checked-out content, and pass fossil test-integrity. The receive path re-deltifies what the serve side expanded, via content.Deltify on the crosslink mlink path, so the expansion the serve side performs does not survive into the store. check-in: a02c9572da user: [email protected] tags: trunk

Adds a wire-efficiency regression guard the issue flagged as missing: correctness-only round-trip tests never asserted card type or wire cost, so the file-card-instead-of-cfile amplification #98 fixed could silently return. TestCloneServesCompressedNotExpandedContent serves a small compressible corpus, clones it over the real HTTP transport, and fails if the server emits any expanded file card or if served bytes exceed 3x the repository's stored size. Card type is the load-bearing signal: the reply container is compressed, so a raw-file-card regression on compressible content hides inside a byte ratio -- the 3x bound is only a coarse backstop.

Also adds a WIRE_MEASURE-gated manual harness that re-measures serve-side amplification against a real fossil client through a byte-counting proxy, with a fossil-serving-fossil control. Current main: 2.06x stored end to end (server response bodies alone are 1.04x, matching the fossil control's 1.03x), down from the 17.9x this issue reported. check-in: 1a73119ed4 user: [email protected] tags: trunk

FossilEncode/FossilDecode implemented only 3 of the 8 escapes the artifact/sync format §4.3 mandates (\s, \n, \\). A field value carrying a real TAB, CR, VT, FF or NUL byte -- as canonical fossil writes it -- was mis-decoded and no longer re-marshalled to its source wire bytes, changing the artifact hash. Unrecognized escapes were also left literal instead of dropping the backslash per spec.

Add the remaining escapes (\t \r \v \f \0) to both directions and make an unrecognized escape drop its backslash, matching canonical fossil fossilize/defossilize (verified against fossil 2.28). Every caller -- A/C/H/L/J/F/T/U cards and the xfer cards -- shares these functions and gets the fix.

Closes #119 check-in: 1bfa6b2094 user: [email protected] tags: trunk

The test step runs `go test $(go list ./... | grep -v '/dst')`. When a package fails to compile, `go list` prints an error to stderr and omits that package from stdout, so it silently drops out of the test run rather than failing CI. `go build ./cmd/libfossil/` only covered the CLI binary's dependency closure, which missed internal/deck when it broke.

Add `go build ./...` ahead of the test step on both driver-tag legs (modernc and test_ncruces) so any package that fails to compile is a loud, fail-fast build error. This subsumes the narrower cmd/libfossil build, so that step is removed rather than kept alongside. check-in: fa558f254d user: [email protected] tags: trunk

The xfer HTTP server let net/http frame large clone/sync replies as Transfer-Encoding: chunked with no Content-Length. Release-tagged fossil <=2.23 reads the reply length only from Content-Length (src/http.c leaves iLength negative otherwise) and aborts with "server did not reply" on any chunked reply above ~256KB, so those clients could not clone a repository larger than that from a libfossil server.

writeXferResponse already materialises the whole response via Encode before the first write, so the exact body length is known for free. Set Content-Length explicitly; net/http then never falls back to chunked.

The fix is unconditional rather than negotiated. The triage proposed sniffing a client capability and keeping chunked for capable clients to avoid the buffering cost of Content-Length. That premise does not hold here: the server never streams -- Encode always returns a complete slice -- so chunked saves no memory over Content-Length, and #88's per-clone bound (DefaultCloneBatchBytes) still caps each reply either way. Content-Length is exactly what canonical fossil's own server emits, so it is strictly the more compatible framing for every client, including builds whose version banner cannot be trusted (#86).

Tests: a reconstructed <=2.23 client that requires a non-negative Content-Length and rejects chunked framing on a >256KB clone response (the discriminating test, since real fossil 2.28 tolerates chunked and cannot reproduce the failure), plus a modern-client no-regression clone of the same corpus. The existing real-fossil multi-batch clone interop test continues to pass unchanged.

Fixes #101 check-in: b3139353e1 user: [email protected] tags: trunk

* Wire manifest.AfterDephantomize into the phantom fill path

AfterDephantomize was a faithful, tested port of Fossil's after_dephantomize (content.c:389-456) that nothing in production ever called — it crosslinked correctly in isolation but sat disconnected from the real receive path.

storeResolvedContent fills a phantom row in place when the full content for a previously-unknown UUID arrives (matching canonical's content_put_ex filling a phantom at content.c:626), but stopped short of crosslinking it or any delta children waiting on it. Return the filled rid from storeResolvedContent and call AfterDephantomize on it from storeReceivedFile once the fill transaction has committed — outside the transaction, since AfterDephantomize opens its own connection via repo.Repo.DB() and calling it from inside the tx's closure would contend with the still-open write lock.

Added an end-to-end regression test that delivers a checkin manifest as a delta against a base that hasn't arrived yet, then delivers the base, and asserts the manifest is crosslinked (its event row exists) immediately — with no explicit call to manifest.Crosslink anywhere in the test. This proves AfterDephantomize fires on the real fill path, not only under its own unit tests.

* Log crosslink failures during AfterDephantomize instead of swallowing them

A crosslink error while filling a phantom blob (or one of its orphan/delta dependents) previously vanished silently, leaving storeReceivedFile report success with the artifact filled but un-crosslinked. Surface it via slog.Warn so real corruption on the fill path is at least visible, matching the non-blocking nit from review. check-in: 94919ca357 user: [email protected] tags: trunk

* fix: select xfer framing by Content-Type (#106); bound clone rounds by the client's decode limit (#109)

seeing which parsed, which made a decompression failure indistinguishable from "wrong framing" (the root of #104). Select framing from the §4 Content-Type instead: application/x-fossil is the §4.1 compressed container, every other type (including application/x-fossil-uncompressed, used by clone-v3 replies) is plain card text — the same rule canonical fossil applies. Verified against fossil 2.28: pull replies arrive as the prefixed container, clone replies as plain text, and no reply is ever an unprefixed raw zlib stream. The former unprefixed-zlib framing, checked first on the unverified belief that fossil emits it, was removed along with the length-prefix/zlib-header aliasing guard that only existed to disambiguate the two compressed framings trial-dispatch conflated. A compressed body that fails to inflate is now reported as the fault it is, never re-fed to the card parser. xfer.Decode takes the Content-Type; byte-oriented callers with no header pass the compressed type explicitly.

crossing one whole, so a round carried budget + one whole artifact. When sub-budget filler preceded a large artifact, that sum exceeded what the client could decode (xfer.MaxDecompressedBytes) and the clone failed with a spurious "declared container length exceeds" error whose threshold depended on incidental filler size. The server now flushes the round and sends an over-bound artifact alone when adding it would cross the client's decode bound, so clonability is a property of the artifact alone. The 2*budget compile-time guard now certifies what it appears to.

* fix: reject unrecognized xfer Content-Type with 415 (#106)

A POST whose Content-Type was absent or unrecognized fell through to the plaintext card decoder, which is exactly the #104 failure shape: possibly- compressed binary fed to the card parser. Request bodies come from untrusted peers, so a body carrying no framing signal is rejected rather than guessed at. Real fossil always sets the header; no conforming peer is affected.

xfer.KnownContentType shares the media-type parsing with the framing check, so the server and Decode agree on what a type means.

Also runs the #109 filler subtests in parallel — serially they pushed internal/sync past the 120s per-package timeout CI uses. check-in: f1236bd031 user: [email protected] tags: trunk

Issue #60's triage was stale: the live truncation bug it describes was already closed on main by 11967ff (#62), which added millisecond rounding to timeToJulian. What remained was a coverage gap, not a defect.

An earlier attempt on this branch also normalized the float64 branch onto the millisecond grid, on the theory that a driver-independent helper is strictly better. That was wrong, and this commit does not do it. A scanned float64 IS the value stored in the row, so snapping it can only move it away from what the row holds. Timeline's pagination cursor depends on the opposite property: its predicate `e.mtime < ? OR (e.mtime = ? AND b.rid < ?)` requires the cursor to compare exactly equal to the row it came from. SQLite's own julianday() computes iJD/86400000.0, a different expression from TimeToJulian's julianEpoch + ms/86400000.0, and the two land one ulp apart on a real fraction of instants — so normalizing alters mtimes written by upstream Fossil, the library's primary real-world input. Raised, the cursor row repeats as the next page's first row; lowered, rows are skipped. Both are silent wrong answers.

The float64 branch therefore stays verbatim, and its doc comment now records why that exactness is load-bearing rather than incidental. The same reasoning applies to tag propagation's `tagxref.mtime < ?`, where SQLite compares the bound value against raw stored floats: an exact bound is the correct one there too, so no normalized variant is introduced for it either.

The one genuine transform stays where it belongs, in the time.Time branch, which must round because ncruces hands back DATETIME columns carrying its own sub-millisecond conversion noise. Its comment now also records the limit of that recovery: an mtime written at finer than millisecond resolution cannot be reproduced through a time.Time at all, and rounding the float64 branch to match would discard precision on both drivers rather than recover any.

Non-functional cleanup: millisPerDay and julianDayFromMillis replace two open-coded copies of the same expression.

Coverage added (no build tag; these run under both drivers): - db: TestScanJulianDayFloatBranchIsBitExact sweeps julianday()-computed mtimes and asserts each scans back bit-for-bit, with a guard that fails the test if the sweep ever stops containing divergent values. Verified to fail against the normalizing version and pass against this one. - db: TestScanJulianDayIsDriverIndependent proves the float64 and time.Time representations of one millisecond-aligned write converge, with noise in both directions. TestScanJulianDaySentinelZero pins the "no mtime" sentinel that bisect's `mtime != 0` guard depends on. - tag: TestPropagateAllOrderingAdjacentMillisecond drives the `tagxref.mtime < ?` decision through ScanJulianDay with adjacent-millisecond mtimes; it fails under a truncating conversion and passes under the rounding one, and passes under modernc regardless — the reason this class went unnoticed twice.

Consumer classification (ScanJulianDay): - manifest/timeline.go NewCursor: ordering/equality, requires exactness - tag/propagate.go PropagateAll -> `tagxref.mtime < ?`: ordering (now covered) - tag/propagate.go childMtime -> mtimeQueue.Less: ordering, traversal-order only (visited set makes it result-neutral) - manifest/log.go, bisect/bisect.go: display-only

Known limitation, left alone deliberately: julianToTime truncates where timeToJulian rounds, so the two are not inverses at sub-millisecond resolution. Pre-existing, now documented; ScanTime's consumers are display paths with no ordering boundary. This commit does not widen the gap. check-in: 78a793dd83 user: [email protected] tags: trunk

* fix: return error when clone stalls with phantoms outstanding

Clone's convergence loop broke out of its round loop as soon as the phantom count stopped decreasing and returned success, even when the phantom table was still non-empty. That leaves the caller holding a repository missing content with no error and exit code 0.

Stopping on a stall is still correct — spinning forever would be worse — but reporting it as success is not. checkStop now returns a PhantomStallError when the loop halts with phantoms remaining, giving the caller a programmatically-reachable count plus a sample of the missing UUIDs for diagnosis. A clean clone still returns nil with an empty phantom table.

Fixes #64.

* fix: preserve partial CloneResult when Clone returns an error

Clone's named result return was never assigned on the error paths — cs.run's cloneResult stayed in a local variable, so a caller catching a PhantomStallError (or a crosslink failure) got a nil result even though a partial one, with the round/blob counts collected so far, was sitting right there. Assign it before returning on both paths.

* fix: make phantom stall error sample deterministic

newPhantomStallError previously took an arbitrary 10 entries from map iteration order before sorting, so the sample was nondeterministic across runs when more than 10 phantoms were outstanding. Sort all UUIDs first, then take the lexicographically-smallest 10, matching what the doc comment already implied.

Addresses a non-blocking nit from review on #64. check-in: e5be6a9199 user: [email protected] tags: trunk

* fix: zero-length file commit panic and stale missing-file carry-forward

Two related bugs in the checkin path:

#68 - Committing a zero-length file panicked in blob.Store, which treated an empty artifact (a normal, well-known Fossil blob) as invalid input. Worse, manifest.Checkin's postcondition defer fired unconditionally during the panic's stack unwind and re-panicked with its own unrelated "manifestRid must be positive" message, masking the real cause. Fixed both: blob.Store now accepts zero-length (and nil) content, and Checkin's defer re-panics with the original panic value instead of asserting a postcondition that was never going to hold mid-unwind. Fixing the panic surfaced a second bug in the same family: buildCommitFiles used len(Content) > 0 to detect "already loaded from disk," which can't distinguish a genuinely empty file from one not yet loaded, so a newly added empty file failed with "no RID for unchanged file." Replaced the length sentinel with an explicit loaded-set.

#79 - A tracked file deleted from disk without Unmanage/Remove was silently carried forward into the new manifest with its last-committed content, rather than being detected. Verified against fossil 2.28: canonical fails a commit when a missing tracked file is in scope (either the implicit "commit everything" case, or explicitly named), but leaves an out-of-scope missing file alone. buildCommitFiles now stats every in-scope tracked file before treating it as unchanged and errors clearly, naming the file, when it's gone; a file outside the commit's scope (relevant only to an explicit Enqueue) is left untouched exactly as before. Updated the two existing tests that had documented the old silent-carry-forward behavior as deliberately deferred to this issue.

* fix: add CHANGELOG entry and unwrap-safe stat checks for #68/#79

Adds the CHANGELOG entries the #79 acceptance criteria required for a user-visible behavior change (missing tracked file now hard-fails a commit instead of silently carrying stale content forward) and for the #68 zero-length-file panic fix.

Also switches checkin.go's two os.IsNotExist(err) checks to errors.Is(err, os.ErrNotExist), which correctly unwraps the %w-wrapped os.ErrNotExist that MemStorage.Stat returns. Production was already correct (OSStorage.Stat returns a raw *PathError), but the tests were only exercising a generic fallback error branch instead of the intended "tracked file missing from disk" message. check-in: 0351167ae5 user: [email protected] tags: trunk

* fix: clone emits cfile with stored content per sec7.2, not expanded file

Our clone server was building xfer.FileCard from cache.Expand(...) -- every artifact fully decompressed, and every delta materialized into full content -- where sec7.2 requires cfile cards carrying the repository's stored compressed content retransmitted verbatim. On real repositories this ran 80-220x more bytes on the wire than the protocol intends, and was the real blocker behind #88's clone-batching fix being unable to bound repositories much past libfossil's own size.

emitCloneBatch now reads blob.Load's stored bytes directly (full content for a whole artifact, delta bytes against DeltaSource for a deltified one) and emits xfer.CFileCard instead of xfer.FileCard, with DeltaSrc and USize (the full reconstructed size, from blob.size) populated correctly for delta rows. content.DeltaSource is exported so this and other callers outside internal/content can ask whether a rid is stored as a delta without duplicating the query.

No client changes were needed: session.go already routes CFileCard through the same handleFileCard path as FileCard, and storeDeltaContent already stores a received delta exactly as given via a create-phantom-if-missing lookup on its source, resolving delta-before-base arrival the way #53's phantom storage model was built for.

DefaultCloneBatchBytes is left at its current value rather than retuned toward canonical's 5,000,000 -- that constant's tuning is #109's territory now that bytesSent tracks stored bytes instead of expanded ones, and retuning it here risks colliding with that work.

* fix: expand deltified rows during clone instead of sending delta cfile

Code review reproduced a real interop regression: emitCloneBatch sends cards in ascending-rid order, but content.Deltify always deltifies the older artifact against the newer one, so a delta's DeltaSource almost always names a rid greater than the delta card's own rid. That means a delta cfile routinely reaches the client before the very source card it names. libfossil's own client tolerates the forward reference (storeDeltaContent phantoms the unseen source and resolves it later), but real fossil 2.28 does not -- the source stays a genuine, unfilled phantom, and content_get() on it during the client's post-clone rebuild pass returns without initializing its output blob, tripping an assertion in blob_copy (blob.c:397) and aborting the client mid-rebuild. Verified independently against a real fossil 2.28 binary cloning a libfossil server holding a delta chain.

emitCloneBatch now expands a deltified row to full content before sending it as a plain (non-delta) cfile, rather than forwarding the stored delta bytes with DeltaSrc set. The card is still zlib-compressed, so the wire-size win over the old FileCard/Expand path survives for every row; only the additional delta-retransmission savings are given up, and only for deltified rows. Re-enabling that needs either a source-before-dependent send order or confirmed forward-reference tolerance in canonical, and is left as a follow-up rather than blocking this fix.

TestEmitCloneBatchExpandsDeltifiedRows (renamed from TestEmitCloneBatchRetransmitsDeltaAsDelta) now pins the new contract: no DeltaSrc, full-sized payload. TestCloneRealFossilWithDeltaChain adds an end-to-end check against a real fossil binary, when one is on PATH. check-in: 0ca5133c62 user: [email protected] tags: trunk

* fix: bound delta.Apply growth per-command and cut ~5x allocation overhead (#81, #82)

Two related fixes to the same command loop in delta.Apply:

- #82: check len(output) against the declared target length after every copy/insert command, not just at the ';' terminator. A malformed delta with many copy commands could previously grow output well past both targetLen and maxDeltaTargetSize before anything noticed, since the only comparison happened at the end.

- #81: once a command has actually executed (proving the delta contains real work, not just an inflated header claim), upgrade output's capacity in a single step sized off len(delta) rather than relying on append's own ~1.25x large-slice growth factor to climb from the 64 KiB initial cap to the final size. That climb was landing near 5x the target size in cumulative allocation; the single upgrade restores near-exact sizing for honest deltas while keeping the tiny-payload/ huge-header attack closed, since a delta with no real commands never reaches the upgrade.

Added TestApply_LoopBoundsAgainstTargetDuringCommands (regression for #82: many copy commands exceeding a small declared target are rejected early, with allocation growth bounded near the declared target rather than the full command sequence) and TestApply_LargeTargetAllocationBounded plus BenchmarkApply_LargeTarget (regression/measurement for #81: a 1 MiB target now allocates ~1.06x its size instead of the prior ~5x).

Cross-checked against fossil 2.28 for wire-format compatibility; full non-dst suite and dst simulation suite (90 scenarios) pass.

* fix: address delta.Apply review nits from #81/#82

Rebuild the #81 regression test/benchmark around a many-small-copy delta shape (4096 copy commands into a 1 MiB target) instead of a Create()-derived single-big-insert delta. The single-insert shape allocates ~1.06x on both fixed and unfixed code (grows once), so it neither exercised the ~5x append-growth-climb regression nor would have caught a future reintroduction of it. Verified against a reverted delta.go: unfixed code now measures ~5.29x on this benchmark, fixed code ~1.06x.

Also move the len(output) > targetLen bound checks ahead of their append calls in both the copy and insert command branches, so an over-target command is rejected before its bytes are appended rather than after -- matches the #82 issue wording exactly, closing the (non-exploitable, since a single command's overshoot is already bounded and resident) gap the reviewer flagged as a nit. check-in: 355e7d9910 user: [email protected] tags: trunk

* manifest: create forumpost on demand, matching canonical rebuild

Crosslink's candidate query names the forumpost table unconditionally, but canonical fossil creates it lazily -- only once a forum artifact needs it -- and fossil rebuild drops it for a repository that never populated it. Crosslink now recreates the table itself before the sweep runs, matching canonical's on-demand behavior instead of erroring with "no such table: forumpost" against a rebuilt repo.

Audited the rest of the on-demand-in-canonical set (ticket, ticketchng) against the current schema: both are created eagerly by canonical at init and survive rebuild, so they don't share this problem.

Added TestCrosslinkForumPostTableDropped (drops the table directly) and TestCrosslinkAfterFossilRebuild (drives an actual fossil rebuild first) to cover the regression, and updated the existing fossilbin comparison test's comment now that the rebuild-last ordering is no longer required.

* manifest: visit crosslink candidates in delta-chain order

Crosslink swept candidates in ascending rid order, but content_deltify stores a blob's older versions as deltas against its newer ones, so delta chains run the opposite direction: high-rid root down to low-rid ancestors. An ascending sweep's first candidate of a chain therefore materializes the whole chain, and the rest are consumed arbitrarily far in the future -- the working set of a whole-repository sweep was the entire repository expanded (8.2 GiB for the Fossil SCM repository).

Candidates are now topologically sorted so a delta's base is always visited before its dependents (deltaChainOrder), matching Fossil's own rebuild_step shape: root first, each descendant one delta application from an already-expanded predecessor. The working set this sweep needs is now bounded by how many chains are in flight at once, not by repository size.

That reordering also changes the order artifact side effects get written in, since content expansion and artifact crosslinking share one loop. Most of what Crosslink writes turned out to already be a pure function of its own artifact (event/plink/mlink/tagxref-origin rows) and needed no change. Two things generalize across the whole plink graph rather than any one artifact and were genuinely order-sensitive:

- leaf table bookkeeping, which inserted the new checkin and deleted its parent -- correct only when parents are linked before their children, which delta-chain order no longer guarantees. - tag propagation, which ran once per checkin from its immediate parent -- reachable only to children plink already held at that moment.

Both are now full, order-independent repair passes (repairLeafTable, repairTagPropagation) run once after the sweep, mirroring Fossil's own manifest_crosslink_end + leaf_rebuild() shape: defer the order-sensitive work and repair it once rather than trying to preserve order through the sweep. tag.propagate's mtime-gated, plink-live-at-call-time design turned out to already be confluent -- replaying every self-declared tag origin once, in any order, converges on the same tagxref state -- so the repair is just doing that instead of depending on visiting order to get there implicitly. Tech-note event replacement and forum thread titles turned out to already have the same confluent shape and needed no change; left comments explaining why.

Also fixes a tag.PropagateAll crash on any origin with a NULL tagxref value (e.g. CrosslinkCluster's cluster tag), surfaced by the new propagation repair actually reaching those rows for the first time.

Regression coverage: a real three-generation checkin chain, forced into a genuine manifest delta chain, that would have left two of three checkins untagged and all three marked leaf under the old per-checkin propagation and incremental leaf bookkeeping.

* fix: address review nits on crosslink order-sensitivity and delta cycles

- deltaChainOrder now returns an error instead of panicking when the candidate delta graph fails to drain. The delta table is on-disk data that can arrive over sync from an untrusted peer, so a cycle (corrupt or hostile repo) should surface as an error rather than crash the process.

- snapshotDerived's digest now covers tagxref (rid/tagid/tagtype/ srcid/origid/value), and TestFossilBinaryReadsCrosslinkedRepo compares it against canonical fossil rebuild -- closing the gap the test previously called out by name ("tagxref is the notable gap").

- Added TestFossilBinaryReadsCrosslinkedRepoBranchAndMerge, exercising the order-sensitive paths incrementalHistory's single-branch history cannot reach: a feature branch diverging from trunk, and a merge commit whose own branch tag must come from its primary parent, not the merged-in one. event/plink/tagxref match canonical fossil row-for-row on this topology.

leaf and mlink are deliberately excluded from that comparison: the fixture surfaced that both have pre-existing gaps against canonical fossil (repairLeafTable counts any plink edge rather than only primary-parent edges; insertCheckinMlinks writes a row for every F-card rather than only changed ones) that predate this fix and are out of scope for #102/#103.

* fix: store received wire frames verbatim instead of re-encoding

Clone reproduced content correctly but not bytes: the receive path decompressed every cfile frame and re-compressed it with blob.Compress's unparameterized zlib writer, so a clone's blob.content never matched its source's — about 0.5% larger on the wapp corpus, purely from re-encoding frames that were already correctly encoded on the wire.

xfer's cfile decoder now hands back StoredBlob alongside the decompressed Content: the same bytes recast into Fossil's on-disk blob format ([4-byte BE size][zlib data]) without a second zlib pass — verbatim when the wire already sent that format (Fossil's send_compressed_file case), or the received zlib stream with a length prefix bolted on when it didn't (our own encoder's plain-zlib case). storeReceivedFile/storeDeltaContent/ storeResolvedContent and blob.StoreDeltaRaw thread that through via a new blob.EncodeForStorage helper, which writes the verbatim bytes when given and only falls back to Compress when there's nothing to preserve — covering both the clone/pull and server-push receive paths.

Locally authored content (never received over the wire) always takes the Compress fallback, so #71's deltification policy is untouched. The clone BUGGIFY corruption test drops storedBlob alongside the corrupted content it's exercising, so verbatim storage can't mask the corruption it exists to catch.

Adds a corpus-level regression test cloning a real multi-revision fossil repo and asserting sum(length(content)) matches between source and clone.

* test: use RequireFossilBin instead of removed HasFossil helper

testutil.HasFossil was removed upstream in favor of RequireFossilBin; this test's skip guard needed the same update to compile against current main. check-in: cc42ad8829 user: [email protected] tags: trunk