Fix duplicate feed items from concurrent syncs

A sync button press racing a page-reload sync could run two sync
requests concurrently. create_feed_item used a check-then-insert
pattern (query for an existing item, then insert if none found), so
both requests could pass the check before either inserted, creating
duplicate items.

- Add a UNIQUE (feed_id, url) constraint on feed_item, keyed on the
  article's link rather than its title since that's RSS's stable
  article identity (a feed editing a headline after publishing, same
  link, would otherwise dupe under title-based matching).
- The migration first collapses any duplicates already created by the
  race, propagating read=true onto the surviving row when any
  duplicate in its group was already read, so the cleanup can't make
  an already-read article look unread.
- create_feed_item now does a single atomic
  INSERT ... ON CONFLICT (feed_id, url) DO NOTHING instead of
  select-then-insert, closing the race entirely.
- Add a test that races two threads on separate connections inserting
  the same item and asserts only one row survives.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012CHcxDSPbHhe7sLJQBRVC9

Cargo.lock

@@ -251,14 +251,13 @@ checksum = "683d7910e743518b0e34f1186f92494becacb047c7b6bf616c96772180fef923"
 
 [[package]]
 name = "ammonia"
-version = "4.1.2"
+version = "4.1.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "17e913097e1a2124b46746c980134e8c954bc17a6a59bb3fde96f088d126dde6"
+checksum = "dc6d763210e2eb7670d1a5183a08bebefa3f97db2a738a684f2ce00bd49f681d"
 dependencies = [
- "cssparser 0.35.0",
+ "cssparser",
- "html5ever 0.35.0",
+ "html5ever",
  "maplit",
- "tendril 0.4.3",
  "url",
 ]
 
@@ -323,15 +322,15 @@ dependencies = [
 
 [[package]]
 name = "anyhow"
-version = "1.0.102"
+version = "1.0.104"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7f202df86484c868dbad7eaa557ef785d5c66295e41b460ef922eca0723b842c"
+checksum = "330a5ed07fa54e4702c9d6c4174f74427fc0ef6e214bbd677ae50a5099946470"
 
 [[package]]
 name = "atom_syndication"
-version = "0.12.8"
+version = "0.12.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "39d8b8ef99e33deb2a51504888222225797f48bace2f0cab01975746a39c05bb"
+checksum = "d48d93a31c932d58b9fd68664a904ae5b74bea37f06c5f68d5bec92f0cdd106d"
 dependencies = [
  "chrono",
  "derive_builder",
@@ -386,12 +385,18 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "72b3254f16251a8381aa12e40e3c4d2f0199f8c6508fbecb9d91f575e0fbb8c6"
 
 [[package]]
-name = "bcrypt"
+name = "base64"
-version = "0.19.1"
+version = "0.23.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "24ae5479c93d3720e4c1dbd6b945b97457c50cb672781104768190371df1a905"
+checksum = "ac07cdecf99051d9a5238b80f35af32cdeba5b336e55d957b318b50137e18da5"
+
+[[package]]
+name = "bcrypt"
+version = "0.19.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a0cd0bd35a28836d528d2b58ad499bc3c5641d59379421b1be9eeb0c2f2b912a"
 dependencies = [
- "base64 0.22.1",
+ "base64 0.23.1",
  "blowfish",
  "getrandom 0.4.2",
  "subtle",
@@ -506,9 +511,9 @@ checksum = "613afe47fcd5fac7ccf1db93babcb082c5994d996f20b8b159f2ad1658eb5724"
 
 [[package]]
 name = "chacha20"
-version = "0.10.0"
+version = "0.10.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6f8d983286843e49675a4b7a2d174efe136dc93a18d69130dd18198a6c167601"
+checksum = "65c35e4b699c7e15ccbe7ee35c005e4fc0a278d22238a2857e6ce2dadeda1b06"
 dependencies = [
  "cfg-if",
  "cpufeatures 0.3.0",
@@ -668,42 +673,19 @@ dependencies = [
  "hybrid-array",
 ]
 
-[[package]]
-name = "cssparser"
-version = "0.35.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4e901edd733a1472f944a45116df3f846f54d37e67e68640ac8bb69689aca2aa"
-dependencies = [
- "cssparser-macros 0.6.1",
- "dtoa-short",
- "itoa",
- "phf 0.11.3",
- "smallvec",
-]
-
 [[package]]
 name = "cssparser"
 version = "0.37.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8c9cdaae01d5ed7882b04d795e7f752f46ff52d2fa3b50a20d28c464510bba98"
 dependencies = [
- "cssparser-macros 0.7.0",
+ "cssparser-macros",
  "dtoa-short",
  "itoa",
- "phf 0.13.1",
+ "phf",
  "smallvec",
 ]
 
-[[package]]
-name = "cssparser-macros"
-version = "0.6.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "13b588ba4ac1a99f7f2964d24b3d896ddc6bf847ee3855dbd4366f058cfcd331"
-dependencies = [
- "quote",
- "syn",
-]
-
 [[package]]
 name = "cssparser-macros"
 version = "0.7.0"
@@ -963,10 +945,10 @@ dependencies = [
 ]
 
 [[package]]
-name = "dotenv"
+name = "dotenvy"
-version = "0.15.0"
+version = "0.15.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "77c90badedccf4105eca100756a0b1289e191f6fcbdadd3cee1d2f614f97da8f"
+checksum = "1aaf95b3e5c8f23aa320147307562d361db0ae0d51242340f558153b4eb2439b"
 
 [[package]]
 name = "downcast-rs"
@@ -1124,16 +1106,6 @@ version = "1.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "42703706b716c37f96a77aea830392ad231f44c9e9a67872fa5548707e11b11c"
 
-[[package]]
-name = "futf"
-version = "0.1.5"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "df420e2e84819663797d1ec6544b13c5be84629e7bb00dc960d6917db2987843"
-dependencies = [
- "mac",
- "new_debug_unreachable",
-]
-
 [[package]]
 name = "futures"
 version = "0.3.32"
@@ -1281,11 +1253,13 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0de51e6874e94e7bf76d726fc5d13ba782deca734ff60d5bb2fb2607c7406555"
 dependencies = [
  "cfg-if",
+ "js-sys",
  "libc",
  "r-efi 6.0.0",
  "rand_core 0.10.1",
  "wasip2",
  "wasip3",
+ "wasm-bindgen",
 ]
 
 [[package]]
@@ -1332,9 +1306,9 @@ dependencies = [
 
 [[package]]
 name = "h2"
-version = "0.4.14"
+version = "0.4.19"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "171fefbc92fe4a4de27e0698d6a5b392d6a0e333506bc49133760b3bcf948733"
+checksum = "ef8e5e5a340588f4452631496976cf8636d4a7ecf600239fdc27615d2530bc16"
 dependencies = [
  "atomic-waker",
  "bytes",
@@ -1396,17 +1370,6 @@ dependencies = [
  "digest 0.10.7",
 ]
 
-[[package]]
-name = "html5ever"
-version = "0.35.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "55d958c2f74b664487a2035fe1dadb032c48718a03b63f3ab0b8537db8549ed4"
-dependencies = [
- "log",
- "markup5ever 0.35.0",
- "match_token",
-]
-
 [[package]]
 name = "html5ever"
 version = "0.39.0"
@@ -1414,7 +1377,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "46a1761807faccc9a19e86944bbf40610014066306f96edcdedc2fb714bcb7b8"
 dependencies = [
  "log",
- "markup5ever 0.39.0",
+ "markup5ever",
 ]
 
 [[package]]
@@ -1492,7 +1455,7 @@ dependencies = [
  "bytes",
  "futures-channel",
  "futures-core",
- "h2 0.4.14",
+ "h2 0.4.19",
  "http 1.4.1",
  "http-body",
  "httparse",
@@ -1899,29 +1862,12 @@ version = "0.1.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "112b39cec0b298b6c1999fee3e31427f74f676e4cb9879ed1a121b43661a4154"
 
-[[package]]
-name = "mac"
-version = "0.1.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c41e0c4fef86961ac6d6f8a82609f55f31b05e4fce149ac5710e439df7619ba4"
-
 [[package]]
 name = "maplit"
 version = "1.0.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3e2e65a1a2e43cfcb47a895c4c8b10d1f4a61097f9f254f183aee60cad9c651d"
 
-[[package]]
-name = "markup5ever"
-version = "0.35.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "311fe69c934650f8f19652b3946075f0fc41ad8757dbb68f1ca14e7900ecc1c3"
-dependencies = [
- "log",
- "tendril 0.4.3",
- "web_atoms 0.1.3",
-]
-
 [[package]]
 name = "markup5ever"
 version = "0.39.0"
@@ -1929,19 +1875,8 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7122d987ec5f704ee56f6e5b41a7d93722e9aae27ae07cafa4036c4d3f9757de"
 dependencies = [
  "log",
- "tendril 0.5.0",
+ "tendril",
- "web_atoms 0.2.4",
+ "web_atoms",
-]
-
-[[package]]
-name = "match_token"
-version = "0.35.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ac84fd3f360fcc43dc5f5d186f02a94192761a080e8bc58621ad4d12296a58cf"
-dependencies = [
- "proc-macro2",
- "quote",
- "syn",
 ]
 
 [[package]]
@@ -2073,55 +2008,25 @@ version = "2.3.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9b4f627cb1b25917193a259e49bdad08f671f8d9708acfd5fe0a8c1455d87220"
 
-[[package]]
-name = "phf"
-version = "0.11.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1fd6780a80ae0c52cc120a26a1a42c1ae51b247a253e4e06113d23d2c2edd078"
-dependencies = [
- "phf_macros 0.11.3",
- "phf_shared 0.11.3",
-]
-
 [[package]]
 name = "phf"
 version = "0.13.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c1562dc717473dbaa4c1f85a36410e03c047b2e7df7f45ee938fbef64ae7fadf"
 dependencies = [
- "phf_macros 0.13.1",
+ "phf_macros",
- "phf_shared 0.13.1",
+ "phf_shared",
  "serde",
 ]
 
-[[package]]
-name = "phf_codegen"
-version = "0.11.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "aef8048c789fa5e851558d709946d6d79a8ff88c0440c587967f8e94bfb1216a"
-dependencies = [
- "phf_generator 0.11.3",
- "phf_shared 0.11.3",
-]
-
 [[package]]
 name = "phf_codegen"
 version = "0.13.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "49aa7f9d80421bca176ca8dbfebe668cc7a2684708594ec9f3c0db0805d5d6e1"
 dependencies = [
- "phf_generator 0.13.1",
+ "phf_generator",
- "phf_shared 0.13.1",
+ "phf_shared",
-]
-
-[[package]]
-name = "phf_generator"
-version = "0.11.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3c80231409c20246a13fddb31776fb942c38553c51e871f8cbd687a4cfb5843d"
-dependencies = [
- "phf_shared 0.11.3",
- "rand 0.8.6",
 ]
 
 [[package]]
@@ -2131,20 +2036,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "135ace3a761e564ec88c03a77317a7c6b80bb7f7135ef2544dbe054243b89737"
 dependencies = [
  "fastrand",
- "phf_shared 0.13.1",
+ "phf_shared",
-]
-
-[[package]]
-name = "phf_macros"
-version = "0.11.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f84ac04429c13a7ff43785d75ad27569f2951ce0ffd30a3321230db2fc727216"
-dependencies = [
- "phf_generator 0.11.3",
- "phf_shared 0.11.3",
- "proc-macro2",
- "quote",
- "syn",
 ]
 
 [[package]]
@@ -2153,22 +2045,13 @@ version = "0.13.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "812f032b54b1e759ccd5f8b6677695d5268c588701effba24601f6932f8269ef"
 dependencies = [
- "phf_generator 0.13.1",
+ "phf_generator",
- "phf_shared 0.13.1",
+ "phf_shared",
  "proc-macro2",
  "quote",
  "syn",
 ]
 
-[[package]]
-name = "phf_shared"
-version = "0.11.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "67eabc2ef2a60eb7faa00097bd1ffdb5bd28e62bf39990626a582201b7a754e5"
-dependencies = [
- "siphasher",
-]
-
 [[package]]
 name = "phf_shared"
 version = "0.13.1"
@@ -2282,9 +2165,9 @@ dependencies = [
 
 [[package]]
 name = "quick-xml"
-version = "0.39.4"
+version = "0.41.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cdcc8dd4e2f670d309a5f0e83fe36dfdc05af317008fea29144da1a2ac858e5e"
+checksum = "e660451e55124f798a69a5af3f49ccfbefbd41910eefd25caf2393e1f3473ec1"
 dependencies = [
  "encoding_rs",
  "memchr",
@@ -2312,15 +2195,16 @@ dependencies = [
 
 [[package]]
 name = "quinn-proto"
-version = "0.11.14"
+version = "0.11.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "434b42fec591c96ef50e21e886936e66d3cc3f737104fdb9b737c40ffb94c098"
+checksum = "04759210543be93709136e28212294a659ef5001836ff4eab4d663e4529bba83"
 dependencies = [
  "aws-lc-rs",
  "bytes",
- "getrandom 0.3.4",
+ "getrandom 0.4.2",
  "lru-slab",
- "rand 0.9.4",
+ "rand 0.10.1",
+ "rand_pcg",
  "ring",
  "rustc-hash",
  "rustls",
@@ -2367,15 +2251,6 @@ version = "6.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f8dcc9c7d52a811697d2151c701e0d08956f92b0e24136cf4cf27b57a6a0d9bf"
 
-[[package]]
-name = "rand"
-version = "0.8.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5ca0ecfa931c29007047d1bc58e623ab12e5590e8c7cc53200d5202b69266d8a"
-dependencies = [
- "rand_core 0.6.4",
-]
-
 [[package]]
 name = "rand"
 version = "0.9.4"
@@ -2407,12 +2282,6 @@ dependencies = [
  "rand_core 0.9.5",
 ]
 
-[[package]]
-name = "rand_core"
-version = "0.6.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ec0be4795e2f6a28069bec0b5ff3e2ac9bafc99e6a9a7dc3547996c5c816922c"
-
 [[package]]
 name = "rand_core"
 version = "0.9.5"
@@ -2428,6 +2297,15 @@ version = "0.10.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "63b8176103e19a2643978565ca18b50549f6101881c443590420e4dc998a3c69"
 
+[[package]]
+name = "rand_pcg"
+version = "0.10.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "caa0f4137e1c0a72f4c651489402276c8e8e1cf081f3b0ba156d2cbeef09e86a"
+dependencies = [
+ "rand_core 0.10.1",
+]
+
 [[package]]
 name = "raw-cpuid"
 version = "11.6.0"
@@ -2493,7 +2371,7 @@ dependencies = [
  "futures-channel",
  "futures-core",
  "futures-util",
- "h2 0.4.14",
+ "h2 0.4.19",
  "http 1.4.1",
  "http-body",
  "http-body-util",
@@ -2539,9 +2417,9 @@ dependencies = [
 
 [[package]]
 name = "rss"
-version = "2.0.13"
+version = "2.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d0e38781082c53bdde56e6081698c06831f69a27eac2593ed6b6cb2511424ad5"
+checksum = "dc13570823abc675c60d7837f1fe7daaf18dd181a3cacb3c6ba7a062eef581c0"
 dependencies = [
  "atom_syndication",
  "derive_builder",
@@ -2564,7 +2442,7 @@ dependencies = [
  "dateparser",
  "diesel",
  "diesel_migrations",
- "dotenv",
+ "dotenvy",
  "env_logger",
  "futures",
  "hmac",
@@ -2713,13 +2591,13 @@ version = "0.27.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "bdd0be4d296f048bfb06dd01bbc80ef789ddd2e55583e8d2e6b804942abfabc2"
 dependencies = [
- "cssparser 0.37.0",
+ "cssparser",
  "ego-tree",
  "getopts",
- "html5ever 0.39.0",
+ "html5ever",
  "precomputed-hash",
  "selectors",
- "tendril 0.5.0",
+ "tendril",
 ]
 
 [[package]]
@@ -2752,12 +2630,12 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8adfa1c298912827b8a28b223b3b874357397ae706e6190acd9bf28cee99114d"
 dependencies = [
  "bitflags",
- "cssparser 0.37.0",
+ "cssparser",
  "derive_more",
  "log",
  "new_debug_unreachable",
- "phf 0.13.1",
+ "phf",
- "phf_codegen 0.13.1",
+ "phf_codegen",
  "precomputed-hash",
  "rustc-hash",
  "servo_arc",
@@ -2956,19 +2834,6 @@ version = "1.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6ce2be8dc25455e1f91df71bfa12ad37d7af1092ae736f3a6cd0e37bc7810596"
 
-[[package]]
-name = "string_cache"
-version = "0.8.9"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bf776ba3fa74f83bf4b63c3dcbbf82173db2632ed8452cb2d891d33f459de70f"
-dependencies = [
- "new_debug_unreachable",
- "parking_lot",
- "phf_shared 0.11.3",
- "precomputed-hash",
- "serde",
-]
-
 [[package]]
 name = "string_cache"
 version = "0.9.0"
@@ -2977,30 +2842,18 @@ checksum = "a18596f8c785a729f2819c0f6a7eae6ebeebdfffbfe4214ae6b087f690e31901"
 dependencies = [
  "new_debug_unreachable",
  "parking_lot",
- "phf_shared 0.13.1",
+ "phf_shared",
  "precomputed-hash",
 ]
 
-[[package]]
-name = "string_cache_codegen"
-version = "0.5.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c711928715f1fe0fe509c53b43e993a9a557babc2d0a3567d0a3006f1ac931a0"
-dependencies = [
- "phf_generator 0.11.3",
- "phf_shared 0.11.3",
- "proc-macro2",
- "quote",
-]
-
 [[package]]
 name = "string_cache_codegen"
 version = "0.6.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "585635e46db231059f76c5849798146164652513eb9e8ab2685939dd90f29b69"
 dependencies = [
- "phf_generator 0.13.1",
+ "phf_generator",
- "phf_shared 0.13.1",
+ "phf_shared",
  "proc-macro2",
  "quote",
 ]
@@ -3069,17 +2922,6 @@ dependencies = [
  "libc",
 ]
 
-[[package]]
-name = "tendril"
-version = "0.4.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d24a120c5fc464a3458240ee02c299ebcb9d67b5249c8848b09d639dca8d7bb0"
-dependencies = [
- "futf",
- "mac",
- "utf-8",
-]
-
 [[package]]
 name = "tendril"
 version = "0.5.0"
@@ -3573,28 +3415,16 @@ dependencies = [
  "wasm-bindgen",
 ]
 
-[[package]]
-name = "web_atoms"
-version = "0.1.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "57ffde1dc01240bdf9992e3205668b235e59421fd085e8a317ed98da0178d414"
-dependencies = [
- "phf 0.11.3",
- "phf_codegen 0.11.3",
- "string_cache 0.8.9",
- "string_cache_codegen 0.5.4",
-]
-
 [[package]]
 name = "web_atoms"
 version = "0.2.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d7cff6eef815df1834fd250e3a2ff436044d82a9f1bc1980ca1dbdf07effc538"
 dependencies = [
- "phf 0.13.1",
+ "phf",
- "phf_codegen 0.13.1",
+ "phf_codegen",
- "string_cache 0.9.0",
+ "string_cache",
- "string_cache_codegen 0.6.1",
+ "string_cache_codegen",
 ]
 
 [[package]]

Cargo.toml

@@ -18,7 +18,7 @@ serde_derive = "1.0.228"
 actix-service = "2.0.3"
 diesel = { version = "2.3", features = ["postgres", "chrono"] }
 diesel_migrations = "2.3"
-dotenv = "0.15.0"
+dotenvy = "0.15"
 bcrypt = "0.19"
 uuid = {version = "1.23", features=["serde", "v4"]}
 jwt = "0.16.0"

migrations/2026-09-10-000000_add_unique_feed_item_url_per_feed/down.sql

@@ -0,0 +1,3 @@
+-- This file should undo anything in `up.sql`
+ALTER TABLE feed_item
+DROP CONSTRAINT feed_item_feed_id_url_unique;

migrations/2026-09-10-000000_add_unique_feed_item_url_per_feed/up.sql

@@ -0,0 +1,36 @@
+-- Your SQL goes here
+
+-- Concurrent syncs for the same feed could previously race past the
+-- application-level "does this article already exist" check and both
+-- insert, producing duplicate feed items. Before enforcing uniqueness,
+-- collapse any duplicates that already exist, keyed on the article's link
+-- (rather than its title) since that's the stable identity RSS items are
+-- built around — some feeds edit a headline after publishing while keeping
+-- the same link, which title-based matching would treat as a new article.
+
+-- If any duplicate in a group was already read, propagate that onto the
+-- surviving (lowest-id) row first, so this one-time cleanup can't make an
+-- already-read article look unread again.
+UPDATE feed_item AS keep
+SET read = true
+FROM feed_item AS dupe
+WHERE keep.feed_id = dupe.feed_id
+  AND keep.url = dupe.url
+  AND keep.id <> dupe.id
+  AND keep.id = (
+    SELECT MIN(candidate.id)
+    FROM feed_item AS candidate
+    WHERE candidate.feed_id = dupe.feed_id
+      AND candidate.url = dupe.url
+  )
+  AND dupe.read = true;
+
+-- Keep the oldest (lowest id) row of each duplicate set.
+DELETE FROM feed_item a
+USING feed_item b
+WHERE a.feed_id = b.feed_id
+  AND a.url = b.url
+  AND a.id > b.id;
+
+ALTER TABLE feed_item
+ADD CONSTRAINT feed_item_feed_id_url_unique UNIQUE (feed_id, url);

src/auth/jwt.rs

@@ -6,7 +6,7 @@ use std::env;
 
 use actix_web::HttpRequest;
 use chrono::{Duration, Utc};
-use dotenv::dotenv;
+use dotenvy::dotenv;
 use hmac::{Hmac, Mac};
 use jwt::{Header, SignWithKey, Token, VerifyWithKey};
 use serde::{Deserialize, Serialize};

src/database.rs

@@ -1,7 +1,7 @@
 use diesel::pg::PgConnection;
 use diesel::prelude::*;
 use diesel_migrations::{embed_migrations, EmbeddedMigrations, MigrationHarness};
-use dotenv::dotenv;
+use dotenvy::dotenv;
 use std::env;
 
 pub const MIGRATIONS: EmbeddedMigrations = embed_migrations!("migrations");

src/main.rs

@@ -1,10 +1,9 @@
 extern crate diesel;
-extern crate dotenv;
 
 use actix_cors::Cors;
 use actix_service::Service;
 use actix_web::{App, HttpMessage, HttpResponse, HttpServer};
-use dotenv::dotenv;
+use dotenvy::dotenv;
 use futures::future::{ok, Either};
 use std::env;
 mod auth;

src/reader/sync.rs

@@ -4,8 +4,7 @@ use crate::error::AppError;
 use crate::json_serialization::user::JsonUser;
 use crate::models::feed::rss_feed::Feed;
 use crate::models::feed_item::new_feed_item::NewFeedItem;
-use crate::models::feed_item::rss_feed_item::FeedItem;
+use crate::schema::feed_item::{feed_id, url};
-use crate::schema::feed_item::{feed_id, title};
 use crate::{
     database::establish_connection,
     schema::{
@@ -143,24 +142,29 @@ fn create_feed_item(item: Item, feed: &Feed, connection: &mut PgConnection) -> a
         }
     }
 
-    let existing_item: Vec<FeedItem> = feed_item::table
+    let new_feed_item = NewFeedItem::new(
-        .filter(feed_id.eq(feed.id))
+        feed.id,
-        .filter(title.eq(&item_title))
+        content.clone(),
-        .load(connection)?;
+        item_title.clone(),
+        item.link.expect("checked above"),
+        Some(time),
+    );
 
-    if existing_item.is_empty() {
+    // `on_conflict` on the (feed_id, url) unique constraint makes this
-        let new_feed_item = NewFeedItem::new(
+    // insert idempotent, so two syncs for the same feed running concurrently
-            feed.id,
+    // (e.g. a sync button press racing a page-reload sync) can't both pass a
-            content.clone(),
+    // check-then-insert race and create duplicate items. Keying on the
-            item_title.clone(),
+    // article's link rather than its title also handles feeds that edit a
-            item.link.expect("checked above"),
+    // headline after publishing while keeping the same link — the link is
-            Some(time),
+    // the stable identity.
-        );
+    let inserted_rows = diesel::insert_into(feed_item::table)
-        let insert_result = diesel::insert_into(feed_item::table)
+        .values(&new_feed_item)
-            .values(&new_feed_item)
+        .on_conflict((feed_id, url))
-            .execute(connection);
+        .do_nothing()
+        .execute(connection)?;
 
-        log::info!("Insert Result: {:?}", insert_result);
+    if inserted_rows > 0 {
+        log::info!("Inserted item: {}", item_title);
     } else {
         log::info!("Item {} already exists.", item_title);
     }
@@ -210,10 +214,11 @@ pub async fn sync(
 #[cfg(test)]
 mod tests {
     use crate::models::feed::new_feed::NewFeed;
+    use crate::models::feed_item::rss_feed_item::FeedItem;
     use crate::models::user::new_user::NewUser;
     use crate::models::user::rss_user::User;
     use crate::schema::users;
-    use crate::test_helpers::unique_suffix;
+    use crate::test_helpers::{delete_feed, delete_user, insert_feed, insert_user, unique_suffix};
     use chrono::Duration;
 
     use super::*;
@@ -440,6 +445,58 @@ mod tests {
             .ok();
     }
 
+    #[actix_web::test]
+    async fn create_feed_item_is_race_safe_under_concurrent_syncs() {
+        let mut connection = establish_connection();
+        let suffix = unique_suffix();
+
+        let user = insert_user(&mut connection, "secret");
+        let feed = insert_feed(&mut connection, user.id);
+
+        let mut item = Item::default();
+        item.set_title(Some(format!("Race test article {suffix}")));
+        item.set_link(Some(format!("https://example.test/race/{suffix}")));
+        item.set_content(Some("<p>Hello world</p>".to_string()));
+
+        // Simulate two concurrent syncs for the same feed (e.g. a sync
+        // button press racing a page-reload sync) — each on its own
+        // connection/thread, released together so they genuinely overlap —
+        // both inserting the same item.
+        let barrier = std::sync::Arc::new(std::sync::Barrier::new(2));
+        let handles: Vec<_> = (0..2)
+            .map(|_| {
+                let feed = feed.clone();
+                let item = item.clone();
+                let barrier = barrier.clone();
+                std::thread::spawn(move || {
+                    let mut connection = establish_connection();
+                    barrier.wait();
+                    create_feed_item(item, &feed, &mut connection)
+                })
+            })
+            .collect();
+
+        for handle in handles {
+            handle.join().unwrap().unwrap();
+        }
+
+        let items: Vec<FeedItem> = feed_item::table
+            .filter(feed_id.eq(feed.id))
+            .load(&mut connection)
+            .unwrap();
+        assert_eq!(
+            1,
+            items.len(),
+            "concurrent syncs must not create duplicate feed items"
+        );
+
+        diesel::delete(feed_item::table.filter(feed_id.eq(feed.id)))
+            .execute(&mut connection)
+            .ok();
+        delete_feed(&mut connection, feed.id);
+        delete_user(&mut connection, user.id);
+    }
+
     #[actix_web::test]
     async fn create_feed_item_strips_onerror_from_feed_image() {
         let mut connection = establish_connection();

vue/src/components/AppNav.vue

@@ -6,16 +6,37 @@ import Modal from './modal/AddUrl.vue'
 
 const router = useRouter()
 const route = useRoute()
-const { sync, showModal, viewMode, toggleViewMode, layout, toggleLayout, markAllRead, feedFilter, feedTitles, feedUnreadCounts, setFeedFilter, unreadCount, lastProgrammaticScroll } = useFeeds()
+const { sync, showModal, viewMode, toggleViewMode, layout, toggleLayout, markAllRead, feedFilter, feedTitles, setFeedFilter, unreadCount, displayedFeedUnreadCounts, refreshUnreadDisplay, lastProgrammaticScroll } = useFeeds()
 
 const headerRef = ref(null)
 
+// Native <select>/<option> has no "is open" state — the closed box just shows
+// the selected option's text verbatim, so per-option unread counts can only be
+// toggled based on focus, since the popup is only ever shown while focused.
+// @focus ~ opening (shows counts); @change (picking an option closes the
+// popup but keeps focus, so no blur fires) and @blur (focus left without
+// picking) ~ closed (counts hidden, so the closed box just shows the name).
+const filterOpen = ref(false)
+
+function onFilterFocus() {
+  filterOpen.value = true
+  refreshUnreadDisplay()
+}
+
+function onFilterChange(event) {
+  setFeedFilter(event.target.value || null)
+  filterOpen.value = false
+}
+
 // Scroll-driven show/hide: the header slides out of view on scroll-down and
-// back in on scroll-up. This is show/hide via `transform` (not the old
+// back in only on scroll-up — never merely by proximity to the top. This is
-// resize behaviour) — the header is position:fixed, so translating it never
+// show/hide via `transform` (not the old resize behaviour) — the header is
-// reflows content, and the app's programmatic scrolls resolve to sensible
+// position:fixed, so translating it never reflows content. The app's
-// states: scrollTo(0, 0) lands near the top → shown; the list-view
+// programmatic scrolls resolve to sensible states without any top-of-page
-// read-correction scrollBy moves only a few px → stays under the threshold.
+// special case: scrollTo(0, 0) (article paging, layout toggle) is itself a
+// large upward jump, so it crosses REVEAL_THRESHOLD like a real scroll-up and
+// reveals the header that way; the list-view read-correction scrollBy moves
+// only a few px → stays under the threshold and leaves a hidden header hidden.
 const hidden = ref(false)
 const REVEAL_THRESHOLD = 12 // px of accumulated travel before toggling
 // When the feed list mutates itself (read-correction scrollBy + array-splice
@@ -30,12 +51,10 @@ let accumulated = 0
 
 function onScroll() {
   const y = Math.max(0, window.scrollY)
-  const headerH = headerRef.value?.offsetHeight ?? 0
 
-  // Always reveal near the very top, and keep it visible while the menu is
+  // Keep the header visible while the menu is open (the dropdown is anchored
-  // open (the dropdown is anchored to the header, so hiding it would slide the
+  // to the header, so hiding it would slide the open menu off-screen).
-  // open menu off-screen).
+  if (menuOpen.value) {
-  if (y <= headerH || menuOpen.value) {
     hidden.value = false
     accumulated = 0
     lastY = y
@@ -78,6 +97,7 @@ onMounted(() => {
   lastY = Math.max(0, window.scrollY)
   window.addEventListener('scroll', onScrollRaf, { passive: true })
   document.addEventListener('click', onDocumentClick)
+  refreshUnreadDisplay()
 })
 
 onUnmounted(() => {
@@ -152,10 +172,12 @@ function handleToggleLayout() {
         class="app-nav__filter"
         :value="feedFilter ?? ''"
         aria-label="Filter by feed"
-        @change="setFeedFilter($event.target.value || null)"
+        @focus="onFilterFocus"
+        @change="onFilterChange"
+        @blur="filterOpen = false"
       >
         <option value="">All feeds</option>
-        <option v-for="title in feedTitles" :key="title" :value="title">{{ title }} ({{ feedUnreadCounts[title] ?? 0 }})</option>
+        <option v-for="title in feedTitles" :key="title" :value="title">{{ title }}<template v-if="filterOpen"> ({{ displayedFeedUnreadCounts[title] ?? 0 }})</template></option>
       </select>
       <button
         class="app-nav__hamburger"

vue/src/components/RssFeeds.vue

@@ -1,5 +1,5 @@
 <script setup>
-import { ref, onMounted, onBeforeUnmount, computed, nextTick, watch } from 'vue';
+import { onMounted, onBeforeUnmount, computed, nextTick, watch } from 'vue';
 import { useFeeds } from '@/composables/useFeeds';
 
 const {
@@ -43,22 +43,6 @@ let touchStartY = null
 const SWIPE_THRESHOLD_X = 50 // min horizontal travel (px) to count as a swipe
 const SWIPE_RESTRAINT_Y = 75 // max vertical travel (px) before it's treated as a scroll, not a swipe
 
-// Drives which slide-in/slide-out transition ('slide-next' / 'slide-prev') the
-// article view uses — set right before the index actually changes, by both
-// the nav buttons and the swipe handler below, so the two triggers animate
-// identically.
-const slideDirection = ref('next')
-
-function navigateToNextArticle() {
-  slideDirection.value = 'next'
-  nextArticle()
-}
-
-function navigateToPrevArticle() {
-  slideDirection.value = 'prev'
-  prevArticle()
-}
-
 function onArticleTouchStart(event) {
   // Ignore multi-touch (pinch-zoom) and swipes starting inside a
   // horizontally-scrollable code block (.article-feature__content :deep(pre))
@@ -83,9 +67,9 @@ function onArticleTouchEnd(event) {
   if (Math.abs(deltaX) < SWIPE_THRESHOLD_X || Math.abs(deltaY) > SWIPE_RESTRAINT_Y) return
 
   if (deltaX < 0) {
-    navigateToNextArticle()
+    nextArticle()
   } else {
-    navigateToPrevArticle()
+    prevArticle()
   }
 }
 
@@ -189,20 +173,22 @@ onMounted(async () => {
         </svg>
         <p class="empty-state__label">All caught up</p>
       </div>
-      <template v-else>
+      <!-- Deliberately no enter/leave transition here: Vue's <Transition>
-        <Transition :name="`slide-${slideDirection}`">
+           component forces a synchronous whole-document reflow
-          <article class="article-feature" :key="currentIndex">
+           (document.body.offsetHeight, in @vue/runtime-dom's forceReflow) on
-            <p class="article-feature__source">{{ feeds[currentIndex].feedTitle }}</p>
+           every enter/leave, regardless of the app's own CSS — confirmed (via
-            <h2 @click="loadReadable(feeds[currentIndex], currentIndex)" class="article-feature__title">{{ feeds[currentIndex].title }}</h2>
+           a DevTools performance trace) to be what was corrupting the header's
-            <h3 class="article-feature__meta">{{ feeds[currentIndex].timestamp }}</h3>
+           native <select>/<button> rendering during article paging. -->
-            <p class="feed-original-link">
+      <article v-else class="article-feature" :key="currentIndex">
-              <a :href="feeds[currentIndex].url" target="_blank" rel="noopener noreferrer">Read original article &#8599;</a>
+        <p class="article-feature__source">{{ feeds[currentIndex].feedTitle }}</p>
-              <button type="button" class="feed-share-btn" :title="shareLabel" @click="shareUrl(feeds[currentIndex].url)">{{ shareLabel }}</button>
+        <h2 @click="loadReadable(feeds[currentIndex], currentIndex)" class="article-feature__title">{{ feeds[currentIndex].title }}</h2>
-            </p>
+        <h3 class="article-feature__meta">{{ feeds[currentIndex].timestamp }}</h3>
-            <p class="article-feature__content" :class="{ 'article-feature__content--readable': feeds[currentIndex].readable }" v-html="feeds[currentIndex].content"></p>
+        <p class="feed-original-link">
-          </article>
+          <a :href="feeds[currentIndex].url" target="_blank" rel="noopener noreferrer">Read original article &#8599;</a>
-        </Transition>
+          <button type="button" class="feed-share-btn" :title="shareLabel" @click="shareUrl(feeds[currentIndex].url)">{{ shareLabel }}</button>
-      </template>
+        </p>
+        <p class="article-feature__content" :class="{ 'article-feature__content--readable': feeds[currentIndex].readable }" v-html="feeds[currentIndex].content"></p>
+      </article>
 
       <div class="article-nav">
         <button
@@ -210,14 +196,14 @@ onMounted(async () => {
           class="article-nav__btn"
           :disabled="currentIndex === 0"
           aria-label="Previous article"
-          @click="navigateToPrevArticle"
+          @click="prevArticle"
         >&uarr;</button>
         <button
           type="button"
           class="article-nav__btn"
           :disabled="feeds.length === 0 || currentIndex === feeds.length - 1"
           aria-label="Next article"
-          @click="navigateToNextArticle"
+          @click="nextArticle"
         >&darr;</button>
       </div>
     </div>
@@ -367,6 +353,13 @@ onMounted(async () => {
   align-items: center;
   padding-top: 1em;
   padding-bottom: 5rem;
+  /* Fill the viewport below the fixed header even when the article content
+     is short, so swipe-to-navigate works anywhere on screen instead of only
+     over the (possibly small) content area. dvh is the accurate unit on
+     mobile, where this matters most; vh is the fallback for browsers
+     without dvh support. */
+  min-height: calc(100vh - var(--app-nav-height, 4.5rem));
+  min-height: calc(100dvh - var(--app-nav-height, 4.5rem));
 }
 
 .article-feature {
@@ -374,46 +367,6 @@ onMounted(async () => {
   max-width: 720px;
 }
 
-/* Slide-in/out when paging between articles (swipe or nav buttons). The
-   outgoing article is pulled out of flex flow during its leave transition so
-   the incoming one can take its place immediately, instead of the two
-   stacking and doubling the page height for the transition's duration. */
-.slide-next-enter-active,
-.slide-next-leave-active,
-.slide-prev-enter-active,
-.slide-prev-leave-active {
-  transition: transform 0.28s ease, opacity 0.28s ease;
-}
-
-.slide-next-leave-active,
-.slide-prev-leave-active {
-  position: absolute;
-  left: 0;
-  right: 0;
-  margin-left: auto;
-  margin-right: auto;
-}
-
-.slide-next-enter-from {
-  transform: translateX(100%);
-  opacity: 0;
-}
-
-.slide-next-leave-to {
-  transform: translateX(-100%);
-  opacity: 0;
-}
-
-.slide-prev-enter-from {
-  transform: translateX(-100%);
-  opacity: 0;
-}
-
-.slide-prev-leave-to {
-  transform: translateX(100%);
-  opacity: 0;
-}
-
 .article-feature__source {
   margin: 0 0 0.5em;
   padding: 0 1rem;

vue/src/components/__tests__/AppNav.spec.js

@@ -239,13 +239,36 @@ describe('AppNav', () => {
 
     const wrapper = mountNav()
     await flushPromises()
+    const select = wrapper.find('.app-nav__filter')
 
-    const options = wrapper.find('.app-nav__filter').findAll('option').map(o => o.text())
+    // Counts only show while the dropdown is open (focused) — see AppNav.vue.
+    await select.trigger('focus')
+
+    const options = select.findAll('option').map(o => o.text())
     // "All feeds" first, then distinct titles sorted alphabetically, each with
     // its unread count.
     expect(options).toEqual(['All feeds', 'Feed A (2)', 'Feed B (1)'])
   })
 
+  it('hides the per-option unread count once the feed filter is closed', async () => {
+    const { allItems } = useFeeds()
+    allItems.value = [
+      { id: 1, feedTitle: 'Feed A', title: 'a', url: 'https://example.test/1', timestamp: '2026-01-01' },
+      { id: 2, feedTitle: 'Feed A', title: 'b', url: 'https://example.test/2', timestamp: '2026-01-02' },
+    ]
+
+    const wrapper = mountNav()
+    await flushPromises()
+    const select = wrapper.find('.app-nav__filter')
+
+    await select.trigger('focus')
+    await select.setValue('Feed A') // fires change, which closes the popup but keeps focus
+    await flushPromises()
+
+    const feedAOption = select.findAll('option').find(o => o.element.value === 'Feed A')
+    expect(feedAOption.text()).toBe('Feed A')
+  })
+
   it('does not render the feed filter when there are no feeds', async () => {
     const wrapper = mountNav()
     await flushPromises()
@@ -306,9 +329,17 @@ describe('AppNav', () => {
       // Reset scroll position so each mount's lastY baseline starts at 0.
       Object.defineProperty(window, 'scrollY', { value: 0, configurable: true, writable: true })
       vi.stubGlobal('requestAnimationFrame', (cb) => { cb(); return 0 })
-      // offsetHeight is 0 in jsdom; give the header a real height so the
+      // getBoundingClientRect() is all-zero in jsdom; give the header a real
-      // "near the top" guard (scrollY <= headerH) has something to compare to.
+      // height so onMounted()'s one-time measurement (used for the
-      vi.spyOn(HTMLElement.prototype, 'offsetHeight', 'get').mockReturnValue(50)
+      // --app-nav-height CSS var — see AppNav.vue) has a realistic value.
+      // This is a prototype-wide spy (scoped to this describe block only, restored in
+      // afterEach), so it returns a full DOMRect-shaped object rather than a
+      // partial one — no test here happens to call getBoundingClientRect() on
+      // anything but the header, but a bare `{ height: 50 }` would silently
+      // hand back `undefined` for top/left/width/etc. to any code that did.
+      vi.spyOn(HTMLElement.prototype, 'getBoundingClientRect').mockReturnValue({
+        height: 50, width: 0, top: 0, left: 0, right: 0, bottom: 0, x: 0, y: 0, toJSON() {},
+      })
     })
 
     afterEach(() => {
@@ -341,19 +372,38 @@ describe('AppNav', () => {
       expect(wrapper.find('header').classes()).not.toContain('app-nav--hidden')
     })
 
-    it('always shows the header near the top of the page', async () => {
+    it('reveals the header on a large upward jump that lands near the top', async () => {
       const wrapper = mountNav()
       scrollTo(400)
       await nextTick()
       expect(wrapper.find('header').classes()).toContain('app-nav--hidden')
 
-      // Back within the header's own height of the top → always revealed.
+      // A jump this large (e.g. article paging's scrollTo(0, 0)) crosses
+      // REVEAL_THRESHOLD on its own — no top-of-page special case needed.
       scrollTo(10)
       await nextTick()
 
       expect(wrapper.find('header').classes()).not.toContain('app-nav--hidden')
     })
 
+    it('does not reveal the header merely for landing near the top', async () => {
+      const wrapper = mountNav()
+      // Hide it with a jump just past the header's own height (50px, mocked
+      // above) plus the reveal threshold.
+      scrollTo(62)
+      await nextTick()
+      expect(wrapper.find('header').classes()).toContain('app-nav--hidden')
+
+      // Move back to right at the header's own height — within the "near the
+      // top" zone the old code always revealed for — but the upward delta
+      // (12px) doesn't exceed REVEAL_THRESHOLD, so a hidden header stays
+      // hidden: proximity to the top is no longer sufficient on its own.
+      scrollTo(50)
+      await nextTick()
+
+      expect(wrapper.find('header').classes()).toContain('app-nav--hidden')
+    })
+
     it('does not let a programmatic upward jump reveal the header mid-read', async () => {
       const { markProgrammaticScroll } = useFeeds()
       const nowSpy = vi.spyOn(performance, 'now').mockReturnValue(1000)

vue/src/composables/__tests__/useFeeds.spec.js

@@ -13,7 +13,7 @@ class FakeIntersectionObserver {
 vi.stubGlobal('IntersectionObserver', FakeIntersectionObserver)
 
 describe('useFeeds', () => {
-  const { feeds, allItems, feedFilter, feedTitles, feedUnreadCounts, unreadCount, setFeedFilter, showMessage, message, showModal, fetchData, sync, getReadable, setInitialLoad, handleIntersection, markAllRead, setupIntersectionObserver } = useFeeds()
+  const { feeds, allItems, feedFilter, feedTitles, feedUnreadCounts, unreadCount, displayedFeedUnreadCounts, refreshUnreadDisplay, setFeedFilter, showMessage, message, showModal, fetchData, sync, getReadable, setInitialLoad, handleIntersection, markAllRead, setupIntersectionObserver } = useFeeds()
 
   beforeEach(() => {
     localStorage.setItem('user-token', 'test-token')
@@ -119,6 +119,32 @@ describe('useFeeds', () => {
     setInitialLoad(false)
   })
 
+  it('refreshes the filter dropdown\'s displayed per-feed counts when list-view scrolling marks an article read', async () => {
+    // displayedFeedUnreadCounts is a frozen snapshot of feedUnreadCounts (see
+    // useFeeds.js) — AppNav's filter <select> renders it instead of the live
+    // computed so paging through article view doesn't force it to repaint.
+    // List-view scrolling is a different code path (handleIntersection) and
+    // should keep it live regardless.
+    allItems.value = [
+      { id: 301, feedTitle: 'Feed A', read: false },
+      { id: 302, feedTitle: 'Feed A', read: false },
+    ]
+    feeds.value = [...allItems.value]
+    refreshUnreadDisplay()
+    expect(displayedFeedUnreadCounts.value).toEqual({ 'Feed A': 2 })
+
+    setInitialLoad(true)
+    axios.put.mockResolvedValue({ status: 200 })
+
+    await handleIntersection([
+      { isIntersecting: false, boundingClientRect: { y: -10 }, target: { id: '0' } },
+    ])
+
+    expect(displayedFeedUnreadCounts.value).toEqual({ 'Feed A': 1 })
+
+    setInitialLoad(false)
+  })
+
   it('ignores the initial observer snapshot on connect so a scrolled-down reconnect cannot mass-mark', async () => {
     feeds.value = [
       { id: 201, title: 'First' },

vue/src/composables/useFeeds.js

@@ -43,6 +43,21 @@ const unreadCount = computed(() => {
     : allItems.value
   return items.filter(i => !i.read).length
 })
+// AppNav renders this snapshot (refreshed via refreshUnreadDisplay, below)
+// for the filter <select>'s per-feed option counts, instead of binding
+// feedUnreadCounts directly — by design, this stays frozen while paging
+// through article view (markCurrentArticleRead marks one article read per
+// page turn, which would otherwise recompute it live on every single swipe).
+// The header's own unread badge stays bound to the live unreadCount (it
+// should update in real time regardless of view). Everywhere else that marks
+// articles read — list-view scrolling (handleIntersection), opening/changing
+// the filter, syncing, mark-all-read, leaving article view — refreshes this
+// snapshot immediately, so it only ever looks stale during article-view
+// paging itself.
+const displayedFeedUnreadCounts = ref({})
+function refreshUnreadDisplay() {
+  displayedFeedUnreadCounts.value = feedUnreadCounts.value
+}
 const message = ref('')
 const showModal = ref(false)
 const viewMode = ref(localStorage.getItem('viewMode') || 'list') // 'list' | 'article' — toggled from the hamburger menu, persisted per device
@@ -242,6 +257,7 @@ async function setFeedFilter(title) {
   feedFilter.value = title // null for "All feeds"
   currentIndex.value = 0
   applyFilter()
+  refreshUnreadDisplay()
   await nextTick()
   setupIntersectionObserver()
 }
@@ -259,6 +275,7 @@ const fetchData = async () => {
     items.sort((a, b) => b.timestamp.localeCompare(a.timestamp));
     allItems.value = items;
     applyFilter();
+    refreshUnreadDisplay();
     await nextTick();
     setupIntersectionObserver();
   } catch (error) {
@@ -346,6 +363,7 @@ function handleIntersection(entries, topbarHeight = 0) {
   feeds.value = feeds.value.filter(feed => !readIds.has(feed.id))
   // Mirror into the master so cleared filters don't resurrect read articles.
   allItems.value = allItems.value.filter(feed => !readIds.has(feed.id))
+  refreshUnreadDisplay()
 
   for (const feed of readFeeds) {
     markRead(feed.id)
@@ -392,6 +410,7 @@ async function markAllRead() {
   // is active) — drop exactly those from the master too.
   allItems.value = allItems.value.filter(feed => !readIds.has(feed.id))
   currentIndex.value = 0
+  refreshUnreadDisplay()
   // markRead swallows its own errors, so Promise.all can't reject here.
   await Promise.all(ids.map(id => markRead(id)))
   showMessageForXSeconds('All articles marked as read.', 5)
@@ -418,6 +437,7 @@ async function leaveArticleView() {
   currentIndex.value = 0
   viewMode.value = 'list'
   localStorage.setItem('viewMode', viewMode.value)
+  refreshUnreadDisplay()
   // The v-if on the list container tears down and recreates all .observe DOM
   // nodes when switching views, so the intersection observer must be
   // re-pointed at the new elements after Vue has finished rendering.
@@ -479,6 +499,8 @@ export function useFeeds() {
     feedTitles,
     feedUnreadCounts,
     unreadCount,
+    displayedFeedUnreadCounts,
+    refreshUnreadDisplay,
     setFeedFilter,
     showMessage,
     message,