C repostate:\sbreak\ssame-mtime\sresolution\sties\sby\sDAG\sancestry,\snot\shash\sorder\n\nThree\scommits\smade\sinside\sthe\ssame\ssecond\smade\s`zit`\sreturn\sthe\sWRONG\sfile\ncontent\sfor\s`tip`\sand\s`trunk`,\sand\smade\sthe\sbinary\scontradict\sitself:\s`zit\sinfo\ntip`\sreported\s"leaf:\sno"\swhile\s`zit\sleaves`\snamed\sthe\ssame\scheck-in\sa\sleaf.\n`zit\scat\sf.txt\stip`\sreturned\sthe\sROOT's\scontent\sand\s`zit\scat\sf.txt\strunk`\nreturned\sthe\sMIDDLE's,\son\sa\sthree-commit\schain\swhose\snewest\scontent\swas\s`v3`.\nA\sversion-control\ssystem\sthat\ssilently\shands\sback\san\sold\srevision\sunder\sa\sname\nthat\smeans\s"newest"\sis\sdisqualifying,\sso\sthis\slands\sbefore\sanything\selse.\n\nWHAT\sWAS\sWRONG\s—\sthree\sindependent\stie\ssites,\snot\sone\n\nThe\soriginally-recorded\sdiagnosis\sblamed\sa\ssingle\slexicographic\sartifact-hash\ntiebreak\sin\s`mergeBaseOf`.\sThat\swas\swrong\sfor\sthe\sreported\ssymptom:\sthe\nRED-proof\sgate\sbuilt\sthe\sequal-mtime\schain\sin\sBOTH\shash\sorderings\sand\sobserved\nIDENTICAL\sfailures,\swhich\srules\sout\shash\sorder\sas\sthe\smechanism.\sFixing\sonly\nthat\sline\swould\shave\sleft\s`cat\stip`\sand\s`cat\strunk`\sstill\sreturning\swrong\nanswers.\sThe\sreal\spicture:\n\n\s\s-\s`tipForm`\s—\s`mtime\s>\sbest_mtime`,\sa\sstrict\s`>`\swith\sno\stiebreak\sat\sall,\sso\n\s\s\s\sthe\sfirst\sentry\sin\s`events`\sINSERTION\sorder\swon.\sSymptom:\s`tip`\s->\sROOT.\n\s\s-\s`resolveName`\s—\sties\ssettled\sby\s`tagxref`\shash-map\sITERATION\sorder.\n\s\s\s\sSymptom:\s`trunk`\s->\sMID.\n\s\s-\s`mergeBaseOf`\s—\slexicographic\sartifact\shash.\sA\sgenuine\sdefect,\sproven\sRED\n\s\s\s\sat\sunit\slevel,\sbut\snot\sthe\scause\sof\sthe\stip/trunk\ssymptom\sand\sunreachable\n\s\s\s\sfrom\sthe\se2e\smerge\spath.\n\nWHAT\sCHANGED\n\nEqual-`event.mtime`\sties\sare\snow\ssettled\sby\sDAG\sancestry:\sa\sdescendant\sbeats\nits\sancestor.\sGenuinely\sconcurrent\snodes\s—\ssame\smtime,\sno\sancestry\srelation\s—\nkeep\sa\sdeterministic\sleast-artifact-hash\sfallback,\sdocumented\sat\seach\ssite;\nhash\sorder\sbetween\sUNRELATED\sleaves\swas\snever\sthe\sbug.\sThe\sshared\shelper\n(`MtimeMaxPick`)\sis\sused\sby\s`tipForm`,\s`resolveName`,\s`openLeafOf`\sand\n`dateResolve`,\sso\severy\ssymbolic-name\ssurface\ssettles\sties\sone\sway.\n\nTimeline\sordering\sgets\sa\ssecond\spass\sthat\sre-orders\seach\sequal-mtime\sRUN\ndescendants-first,\sdeliberately\soverriding\sthe\shash\stiebreak.\sIt\sis\sa\sper-run\nrepeated-maximal-element\sextraction,\sNOT\sa\ssort\spredicate:\s"descends-from,\selse\nhash"\sis\snot\sa\sstrict\sweak\sorder,\sand\shanding\sit\sto\s`std.mem.sort`\swould\sbe\nundefined\sbehavior.\sRuns\sare\sbounded\sby\sthe\scheck-ins\ssharing\sone\smillisecond.\n\nSettling\sa\stie\sby\sancestry\sallocates,\sso\s`resolveName`/`resolve`/`openLeafOf`\ngained\s`OutOfMemory`.\sEvery\scaller\sswitches\sit\sas\san\sABORT,\snever\sas\sa\nmismatch\sor\s"already\scorrect"\sverdict\s—\sreporting\san\sallocation\sfailure\sas\sthe\nexit-0\sup-to-date\smessage\sis\sexactly\sthe\slie\sthose\sswitches\sexist\sto\sprevent.\n`repository_test`'s\sclosed-error-set\sassertion\smoved\s2\s->\s3\sfor\sthat\sreason:\nit\sencoded\sthe\spre-fix\sset,\snot\san\sinconvenient\sexpectation.\n\nTwo\sride-alongs\son\sthe\ssame\sresolution\ssurface:\n\n\s\s-\sSF1\s—\s`zit\supdate\strunk`\sused\sto\sfail\sas\s"invalid\scheck-in\sID":\supdate\n\s\s\s\saccepted\sONLY\scanonical\s40/64-hex.\sIts\sargument\sis\sa\scheck-in\sname\slike\n\s\s\s\severy\sother\sverb's,\sso\sit\snow\sruns\sthe\sshared\s8.3\sprocedure.\sA\scanonical\n\s\s\s\sID\sstill\sshort-circuits,\sleaving\supdate's\scold\spath\sbyte-for-byte\sas\sit\swas.\n\s\s-\sSF5\s—\sa\s`tip`\sthat\snames\sa\snon-leaf\sis\snow\san\sin-binary\sassertion,\snot\sjust\n\s\s\s\sa\stest.\sIt\sis\slegitimate\sONLY\sunder\sa\snon-monotone\sclock\s(a\schild\sstamped\n\s\s\s\sstrictly\searlier\sthan\sits\sparent);\sa\schild\sthat\sTIES\sits\sparent\smeans\sthe\n\s\s\s\sancestry\stiebreak\sfailed\sto\sfire,\swhich\sis\sthe\sdefect\sitself.\sThis\n\s\s\s\stripwire\swould\shave\scaught\sthe\soriginal\sbug.\n\nRED\sPROOF\s(recorded\sby\sthe\sRED-proof\sgate,\s2026-07-19;\sper\sBLOCKER-FIX-PLAN.md\nsection\s2,\sno\sproduct\scode\schanged\suntil\sRED\swas\sproven)\n\nUnit,\s`src/repostate_test.zig`,\sdeterministic\sequal-mtime\schains\sbuilt\sdirectly\nin\sBOTH\shash\sorderings\s—\sno\swall-clock\sdependence:\n\n\s\srepostate\sREGRESSION\sB1:\stip\sresolves\sto\sthe\sdescendant\son\san\sequal-mtime\n\s\s\s\schain\s(head\shas\sthe\sgreatest\shash)\n\s\srepostate\sREGRESSION\sB1:\stip\sresolves\sto\sthe\sdescendant\son\san\sequal-mtime\n\s\s\s\schain\s(head\shas\sthe\sleast\shash)\n\s\srepostate\sREGRESSION\sB1:\sresolveName\spicks\sthe\sdescendant\son\san\sequal-mtime\n\s\s\s\schain\s(head\shas\sthe\sgreatest\shash)\n\s\srepostate\sREGRESSION\sB1:\sresolveName\spicks\sthe\sdescendant\son\san\sequal-mtime\n\s\s\s\schain\s(head\shas\sthe\sleast\shash)\n\s\srepostate\sREGRESSION\sB1:\stip\sand\sresolveName\sagree\swith\sthe\sleaf\sset\sin\sboth\n\s\s\s\shash\sorderings\n\s\srepostate\sREGRESSION\sB1:\smergeBaseOf\spicks\sthe\sdeepest\scommon\sancestor\swhen\n\s\s\s\severy\scandidate\sshares\san\smtime\s\s\s[failed\spre-fix:\sexpected\s2,\sfound\s1]\n\nEnd-to-end,\s`src/e2e.zig`,\ssame-second\scommits\swith\sNO\ssleep\sbetween\sthem\s—\nsame-second\sIS\sthe\spoint:\n\n\s\scli\sREGRESSION\sB1:\ssame-second\scommits\sresolve\stip\sand\strunk\sto\sthe\snewest\n\s\s\s\scheck-in\n\s\scli\sREGRESSION\sB1\s(SF1):\supdate\saccepts\sa\ssymbolic\sname\sand\slands\son\sthe\n\s\s\s\snewest\scheck-in\n\s\scli\sREGRESSION\sB1:\sopen\smaterializes\sthe\snewest\ssame-second\scheck-in\sinto\sa\n\s\s\s\sfresh\sclone\n\s\scli\sREGRESSION\sB1:\sa\ssame-second\stwo-branch\smerge\spicks\sthe\scorrect\sbase\sand\n\s\s\s\sis\snever\sup\sto\sdate\n\nAll\sof\sthe\sabove\sfailed\sagainst\spre-fix\strunk;\sthe\stwo\shash-ordering\spairs\nfailed\sIDENTICALLY,\swhich\sis\sthe\sevidence\sthat\sretired\sthe\shash-order\stheory.\n\nTEST\sEVIDENCE\sNOW\n\nIn\sthis\sworktree\sat\sthe\scommitted\stree:\s`zig\sfmt\s--check\s.`,\s`zig\sbuild`,\sand\n`zig\sbuild\stest`\seach\sexit\s0\s—\sfull\sbattery,\sno\sfiltering.\sThe\sonly\spre-existing\nexpectation\schanged\sis\sthe\s`repository_test`\serror-set\scount\snoted\sabove,\sand\sit\nchanged\sbecause\sit\sencoded\sthe\sold\sset.\n\nMarkers\s`//\sREGRESSION\sB1:`\sare\sstable\sso\sstate\sprobes\scan\sgrep\strunk\sfor\sthem.\n\nNo\sborrowed\stechnique:\sthe\sancestry\stiebreak\sand\sthe\sper-run\stopological\nmicro-ordering\sare\soriginal\sto\sthis\schange.\n
D 2026-07-19T11:56:16.100
F .fossil-settings/ignore-glob 3580f973d7097226f91a27c7b61ec13d9d07880d95549f9b90ce86da5d867a23
F .github/workflows/ci.yml 6d343370ac09cc6826509b7c22e045fd7c8b2272504ced464c382a24588d0878
F LICENSE 702ae7ff835a2a971dae11c5cae039803bf394b77a6d8ec9f18693e449eaaf26
F README.md 62e1f936cc2ea0e33d717539bdffd6126a639843069bd6256359f2b15cb06232
F build.zig 43c12a0eaffed3817646b3021862ee1add3b8536a85b531b7cf55319c3b0e95e
F build.zig.zon 0eade544d4d7fc5a620348c6f29cc9219ff8c6d6377a05e756ca89860a524781
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F docs/rfcs/draft-fossil-delta-format-00.txt d8025d6d75322e33887c3334a4b9cc729960028b3c994ed01e5a474e4b388fd2
F docs/rfcs/draft-fossil-repo-state-00.txt fd413bcb28001a8a07009ca0c769cfe666394ba79dd4f14a6461f2b592049595
F docs/rfcs/draft-fossil-sync-protocol-00.txt aa55791464a54ef4b651df8780ba5c46e95c723c7997d09a5b727fef658f920a
F scripts/mirror-export.sh cc1130129e3c320cb9c1c5a05f505e45ece23d6bb3e0228da8e7ffe97bd5612b x
F src/annotate.zig 0a6b6728099e63c84681d1e5228ebb45fafb55d65df1720358247fd6e6532c63
F src/artifact.zig c630afd9fbbcfaccd7b823105b4d05db1dc85b6af03080a6d58635ed064672ca
F src/artifact_fuzz.zig 8bb359ddfe790818e109a1dd7ac0c1b5cec1a8fdc556f37e73504cdb7f933e17
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F src/packaging_test.zig b802ada92f1ade1b62e3d1cfc36549c9b8d05be5430bd33d440bc93d7cd3600f
F src/repocache.zig aae232a6b1b86e27c5242c0ee17ce9f2544299d99cf4936d8c2c9000e3166884
F src/repoimage.zig 7d2dc2f3c145e10e2d9ba6997705fd61a0cc0aedde8e171c253163d1279ccdd5
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F src/repository_test.zig 17bdf4c7042f846f928570a47821035f936238f70f3d61d8d2ea3729d5f58868
F src/repostate.zig b4944efab53752f12da2871b2bc46251dbdacd4fcba27e38c61c4fe4d40d1df1
F src/repostate_test.zig e5699688b0f43b7480ed5d89f11585c2f61114bbe3ec9dae5061741f37b37e7a
F src/repoview.zig ec2958e1e8fd955c761d240ab80c3b3f62e3473991713c25ed5a603df984e403
F src/rfc_vectors/artifact_a1_1_sha1_manifest.txt 82d8fc78b3fbf85efe80cb05e79db40c910bf0551e55b728c6f9c2ca7a42ddb6
F src/rfc_vectors/artifact_a1_2_sha3_technote.txt 832e850f83aab2e2a754aa97591109f7f05fb41e4126c7e71c88a59d6d17e55d
F src/rfc_vectors/artifact_a3_rcard_manifest.txt 47e412ef211f095e93275fadf527909e581eef42357d8437fc7e299bfc3e62a7
F src/rfc_vectors/sync_a1_round1_reply.txt 638813029b10f81303b88859279afb17095d7c779c993f4267870909acabbeb9
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F src/sim/net.zig 8fb057012ce0a33f67c928cd696bc2761fea8ba4012b2daa33871b2ba5dfe772
F src/sim/oracle.zig 04b81d9472a0529d9e9d030779304c3d6c930f4db20b800ae3f9cbc5c178969a
F src/sim/storage_sweep.zig 5472d632347079fb5c7e7ae300b46c6e8202b91202b1c51b181dd3c7bab8a306
F src/sim/sync_gen.zig 238d46942915b5c0e989dfc738b5927b5228468ea123e6f17b6fb593aa5cbf6e
F src/sim/sync_sweep.zig 5458a84be08823d2d0fc9464665f1c3f3f26563185dc9ae24cf73259faa5d40e
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T *sym-blockers *
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U dmestas
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