diff --git a/Cargo.lock b/Cargo.lock
index 68ecef5..b068844 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -186,6 +186,18 @@ version = "0.2.21"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "683d7910e743518b0e34f1186f92494becacb047c7b6bf616c96772180fef923"
 
+[[package]]
+name = "ammonia"
+version = "4.1.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dc6d763210e2eb7670d1a5183a08bebefa3f97db2a738a684f2ce00bd49f681d"
+dependencies = [
+ "cssparser",
+ "html5ever",
+ "maplit",
+ "url",
+]
+
 [[package]]
 name = "android_system_properties"
 version = "0.1.5"
@@ -445,6 +457,15 @@ version = "0.22.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "72b3254f16251a8381aa12e40e3c4d2f0199f8c6508fbecb9d91f575e0fbb8c6"
 
+[[package]]
+name = "bincode"
+version = "1.3.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b1f45e9417d87227c7a56d22e471c6206462cba514c7590c09aff4cf6d1ddcad"
+dependencies = [
+ "serde",
+]
+
 [[package]]
 name = "bit-set"
 version = "0.8.0"
@@ -484,6 +505,31 @@ dependencies = [
  "generic-array",
 ]
 
+[[package]]
+name = "bon"
+version = "3.9.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a602c73c7b0148ec6d12af6fd5cc7a46e2eacc8878271a999abac56eed12f561"
+dependencies = [
+ "bon-macros",
+ "rustversion",
+]
+
+[[package]]
+name = "bon-macros"
+version = "3.9.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6dee98b0db6a962de883bf5d20362dee4d7ca0d12fe39a7c6c73c844e1cd7c1f"
+dependencies = [
+ "darling 0.23.0",
+ "ident_case",
+ "prettyplease",
+ "proc-macro2",
+ "quote",
+ "rustversion",
+ "syn",
+]
+
 [[package]]
 name = "borrow-or-share"
 version = "0.2.4"
@@ -544,6 +590,15 @@ dependencies = [
  "pkg-config",
 ]
 
+[[package]]
+name = "caseless"
+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8b6fd507454086c8edfd769ca6ada439193cdb209c7681712ef6275cccbfe5d8"
+dependencies = [
+ "unicode-normalization",
+]
+
 [[package]]
 name = "cc"
 version = "1.2.60"
@@ -623,6 +678,7 @@ dependencies = [
  "anstyle",
  "clap_lex",
  "strsim",
+ "terminal_size",
 ]
 
 [[package]]
@@ -716,6 +772,30 @@ version = "0.4.31"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "75984efb6ed102a0d42db99afb6c1948f0380d1d91808d5529916e6c08b49d8d"
 
+[[package]]
+name = "comrak"
+version = "0.54.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0d5910408554659ed848ff469e67ec83b30f179e72cec286cfdae64d1616f466"
+dependencies = [
+ "bon",
+ "caseless",
+ "clap",
+ "emojis",
+ "entities",
+ "finl_unicode",
+ "fmt2io",
+ "jetscii",
+ "phf",
+ "phf_codegen",
+ "rustc-hash",
+ "shell-words",
+ "smallvec",
+ "syntect",
+ "typed-arena",
+ "xdg",
+]
+
 [[package]]
 name = "concurrent-queue"
 version = "2.5.0"
@@ -931,6 +1011,17 @@ dependencies = [
  "typenum",
 ]
 
+[[package]]
+name = "cssparser"
+version = "0.37.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8c9cdaae01d5ed7882b04d795e7f752f46ff52d2fa3b50a20d28c464510bba98"
+dependencies = [
+ "dtoa-short",
+ "itoa",
+ "smallvec",
+]
+
 [[package]]
 name = "darling"
 version = "0.20.11"
@@ -1143,6 +1234,21 @@ dependencies = [
  "const-random",
 ]
 
+[[package]]
+name = "dtoa"
+version = "1.0.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4c3cf4824e2d5f025c7b531afcb2325364084a16806f6d47fbc1f5fbd9960590"
+
+[[package]]
+name = "dtoa-short"
+version = "0.3.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cd1511a7b6a56299bd043a9c167a6d2bfb37bf84a6dfceaba651168adfb43c87"
+dependencies = [
+ "dtoa",
+]
+
 [[package]]
 name = "dunce"
 version = "1.0.5"
@@ -1164,6 +1270,15 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "emojis"
+version = "0.8.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0a4d5d50b0b58df5173d8ff1192b4d1422ceae5d981b30d4b6f8ed1d673a2bc4"
+dependencies = [
+ "phf",
+]
+
 [[package]]
 name = "encode_unicode"
 version = "1.0.0"
@@ -1179,6 +1294,12 @@ dependencies = [
  "cfg-if",
 ]
 
+[[package]]
+name = "entities"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b5320ae4c3782150d900b79807611a59a99fc9a1d61d686faafc24b93fc8d7ca"
+
 [[package]]
 name = "equivalent"
 version = "1.0.2"
@@ -1224,6 +1345,17 @@ version = "0.1.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7360491ce676a36bf9bb3c56c1aa791658183a54d2744120f27285738d90465a"
 
+[[package]]
+name = "fancy-regex"
+version = "0.16.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "998b056554fbe42e03ae0e152895cd1a7e1002aec800fdc6635d20270260c46f"
+dependencies = [
+ "bit-set",
+ "regex-automata",
+ "regex-syntax",
+]
+
 [[package]]
 name = "fancy-regex"
 version = "0.18.0"
@@ -1298,12 +1430,14 @@ dependencies = [
 name = "fastskill-core"
 version = "0.9.150"
 dependencies = [
+ "ammonia",
  "anyhow",
  "assert_cmd",
  "async-trait",
  "axum",
  "chrono",
  "cli-framework",
+ "comrak",
  "config",
  "dirs 6.0.0",
  "futures",
@@ -1366,6 +1500,12 @@ version = "0.1.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "5baebc0774151f905a1a2cc41989300b1e6fbb29aff0ceffa1064fdd3088d582"
 
+[[package]]
+name = "finl_unicode"
+version = "1.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9844ddc3a6e533d62bba727eb6c28b5d360921d5175e9ff0f1e621a5c590a4d5"
+
 [[package]]
 name = "flate2"
 version = "1.1.9"
@@ -1396,6 +1536,12 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "fmt2io"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6b6129284da9f7e5296cc22183a63f24300e945e297705dcc0672f7df01d62c8"
+
 [[package]]
 name = "fnv"
 version = "1.0.7"
@@ -1780,6 +1926,16 @@ dependencies = [
  "digest",
 ]
 
+[[package]]
+name = "html5ever"
+version = "0.39.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "46a1761807faccc9a19e86944bbf40610014066306f96edcdedc2fb714bcb7b8"
+dependencies = [
+ "log",
+ "markup5ever",
+]
+
 [[package]]
 name = "http"
 version = "0.2.12"
@@ -2252,6 +2408,12 @@ version = "1.0.18"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8f42a60cbdf9a97f5d2305f08a87dc4e09308d1276d28c869c684d7777685682"
 
+[[package]]
+name = "jetscii"
+version = "0.5.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "47f142fe24a9c9944451e8349de0a56af5f3e7226dc46f3ed4d4ecc0b85af75e"
+
 [[package]]
 name = "jni"
 version = "0.22.4"
@@ -2344,7 +2506,7 @@ dependencies = [
  "bytecount",
  "data-encoding",
  "email_address",
- "fancy-regex",
+ "fancy-regex 0.18.0",
  "fraction",
  "getrandom 0.3.4",
  "idna",
@@ -2424,6 +2586,12 @@ dependencies = [
  "vcpkg",
 ]
 
+[[package]]
+name = "linked-hash-map"
+version = "0.5.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0717cef1bc8b636c6e1c1bbdefc09e6322da8a9321966e8928ef80d20f7f770f"
+
 [[package]]
 name = "linux-raw-sys"
 version = "0.4.15"
@@ -2484,6 +2652,23 @@ dependencies = [
  "pkg-config",
 ]
 
+[[package]]
+name = "maplit"
+version = "1.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3e2e65a1a2e43cfcb47a895c4c8b10d1f4a61097f9f254f183aee60cad9c651d"
+
+[[package]]
+name = "markup5ever"
+version = "0.39.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7122d987ec5f704ee56f6e5b41a7d93722e9aae27ae07cafa4036c4d3f9757de"
+dependencies = [
+ "log",
+ "tendril",
+ "web_atoms",
+]
+
 [[package]]
 name = "matchers"
 version = "0.2.0"
@@ -2595,6 +2780,12 @@ dependencies = [
  "tempfile",
 ]
 
+[[package]]
+name = "new_debug_unreachable"
+version = "1.0.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "650eef8c711430f1a879fdd01d4745a7deea475becfb90269c06775983bbf086"
+
 [[package]]
 name = "newline-converter"
 version = "0.3.0"
@@ -2745,6 +2936,28 @@ version = "1.70.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "384b8ab6d37215f3c5301a95a4accb5d64aa607f1fcb26a11b5303878451b4fe"
 
+[[package]]
+name = "onig"
+version = "6.5.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0cc3cbf698f9438986c11a880c90a6d04b9de27575afd28bbf45b154b6c709e2"
+dependencies = [
+ "bitflags 2.11.1",
+ "libc",
+ "once_cell",
+ "onig_sys",
+]
+
+[[package]]
+name = "onig_sys"
+version = "69.9.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1e68317604e77e53b85896388e1a803c1d21b74c899ec9e5e1112db90735edd7"
+dependencies = [
+ "cc",
+ "pkg-config",
+]
+
 [[package]]
 name = "openssl"
 version = "0.10.81"
@@ -2920,6 +3133,45 @@ dependencies = [
  "sha2",
 ]
 
+[[package]]
+name = "phf"
+version = "0.13.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c1562dc717473dbaa4c1f85a36410e03c047b2e7df7f45ee938fbef64ae7fadf"
+dependencies = [
+ "phf_shared",
+ "serde",
+]
+
+[[package]]
+name = "phf_codegen"
+version = "0.13.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "49aa7f9d80421bca176ca8dbfebe668cc7a2684708594ec9f3c0db0805d5d6e1"
+dependencies = [
+ "phf_generator",
+ "phf_shared",
+]
+
+[[package]]
+name = "phf_generator"
+version = "0.13.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "135ace3a761e564ec88c03a77317a7c6b80bb7f7135ef2544dbe054243b89737"
+dependencies = [
+ "fastrand 2.4.1",
+ "phf_shared",
+]
+
+[[package]]
+name = "phf_shared"
+version = "0.13.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e57fef6bc5981e38c2ce2d63bfa546861309f875b8a75f092d1d54ae2d64f266"
+dependencies = [
+ "siphasher",
+]
+
 [[package]]
 name = "pin-project-lite"
 version = "0.2.17"
@@ -2938,6 +3190,19 @@ version = "0.2.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b4596b6d070b27117e987119b4dac604f3c58cfb0b191112e24771b2faeac1a6"
 
+[[package]]
+name = "plist"
+version = "1.10.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7da1d65da6dd5d1e44199ac0f58712d241c0f439f80adea8924d832384087f85"
+dependencies = [
+ "base64 0.22.1",
+ "indexmap",
+ "quick-xml",
+ "serde",
+ "time",
+]
+
 [[package]]
 name = "potential_utf"
 version = "0.1.5"
@@ -2962,6 +3227,12 @@ dependencies = [
  "zerocopy",
 ]
 
+[[package]]
+name = "precomputed-hash"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "925383efa346730478fb4838dbe9137d2a47675ad789c546d150a6e1dd4ab31c"
+
 [[package]]
 name = "predicates"
 version = "3.1.4"
@@ -3033,6 +3304,15 @@ dependencies = [
  "unicode-ident",
 ]
 
+[[package]]
+name = "quick-xml"
+version = "0.41.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e660451e55124f798a69a5af3f49ccfbefbd41910eefd25caf2393e1f3473ec1"
+dependencies = [
+ "memchr",
+]
+
 [[package]]
 name = "quinn"
 version = "0.11.9"
@@ -3985,6 +4265,12 @@ dependencies = [
  "lazy_static",
 ]
 
+[[package]]
+name = "shell-words"
+version = "1.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dc6fe69c597f9c37bfeeeeeb33da3530379845f10be461a66d16d03eca2ded77"
+
 [[package]]
 name = "shlex"
 version = "1.3.0"
@@ -4051,6 +4337,12 @@ version = "2.7.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "bbbb5d9659141646ae647b42fe094daf6c6192d1620870b449d9557f748b2daa"
 
+[[package]]
+name = "siphasher"
+version = "1.0.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8ee5873ec9cce0195efcb7a4e9507a04cd49aec9c83d0389df45b1ef7ba2e649"
+
 [[package]]
 name = "slab"
 version = "0.4.12"
@@ -4120,6 +4412,30 @@ version = "1.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6ce2be8dc25455e1f91df71bfa12ad37d7af1092ae736f3a6cd0e37bc7810596"
 
+[[package]]
+name = "string_cache"
+version = "0.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a18596f8c785a729f2819c0f6a7eae6ebeebdfffbfe4214ae6b087f690e31901"
+dependencies = [
+ "new_debug_unreachable",
+ "parking_lot",
+ "phf_shared",
+ "precomputed-hash",
+]
+
+[[package]]
+name = "string_cache_codegen"
+version = "0.6.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "585635e46db231059f76c5849798146164652513eb9e8ab2685939dd90f29b69"
+dependencies = [
+ "phf_generator",
+ "phf_shared",
+ "proc-macro2",
+ "quote",
+]
+
 [[package]]
 name = "strsim"
 version = "0.11.1"
@@ -4169,6 +4485,28 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "syntect"
+version = "5.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "656b45c05d95a5704399aeef6bd0ddec7b2b3531b7c9e900abbf7c4d2190c925"
+dependencies = [
+ "bincode",
+ "fancy-regex 0.16.2",
+ "flate2",
+ "fnv",
+ "once_cell",
+ "onig",
+ "plist",
+ "regex-syntax",
+ "serde",
+ "serde_derive",
+ "serde_json",
+ "thiserror 2.0.18",
+ "walkdir",
+ "yaml-rust",
+]
+
 [[package]]
 name = "system-configuration"
 version = "0.5.1"
@@ -4224,6 +4562,25 @@ dependencies = [
  "windows-sys 0.61.2",
 ]
 
+[[package]]
+name = "tendril"
+version = "0.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5fed54709c5b3a53d09bb1c113ea4f5ceafd1e772ddcb0030a82e1d56c087b08"
+dependencies = [
+ "new_debug_unreachable",
+]
+
+[[package]]
+name = "terminal_size"
+version = "0.4.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "230a1b821ccbd75b185820a1f1ff7b14d21da1e442e22c0863ea5f08771a8874"
+dependencies = [
+ "rustix 1.1.4",
+ "windows-sys 0.61.2",
+]
+
 [[package]]
 name = "termtree"
 version = "0.5.1"
@@ -4286,10 +4643,12 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "743bd48c283afc0388f9b8827b976905fb217ad9e647fae3a379a9283c4def2c"
 dependencies = [
  "deranged",
+ "itoa",
  "num-conv",
  "powerfmt",
  "serde_core",
  "time-core",
+ "time-macros",
 ]
 
 [[package]]
@@ -4298,6 +4657,16 @@ version = "0.1.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7694e1cfe791f8d31026952abf09c69ca6f6fa4e1a1229e18988f06a04a12dca"
 
+[[package]]
+name = "time-macros"
+version = "0.2.27"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2e70e4c5a0e0a8a4823ad65dfe1a6930e4f4d756dcd9dd7939022b5e8c501215"
+dependencies = [
+ "num-conv",
+ "time-core",
+]
+
 [[package]]
 name = "tiny-keccak"
 version = "2.0.2"
@@ -4680,6 +5049,12 @@ dependencies = [
  "thiserror 2.0.18",
 ]
 
+[[package]]
+name = "typed-arena"
+version = "2.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6af6ae20167a9ece4bcb41af5b80f8a1f1df981f6391189ce00fd257af04126a"
+
 [[package]]
 name = "typeid"
 version = "1.0.3"
@@ -4716,6 +5091,15 @@ version = "1.0.24"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e6e4313cd5fcd3dad5cafa179702e2b244f760991f45397d14d4ebf38247da75"
 
+[[package]]
+name = "unicode-normalization"
+version = "0.1.25"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5fd4f6878c9cb28d874b009da9e8d183b5abc80117c40bbd187a1fde336be6e8"
+dependencies = [
+ "tinyvec",
+]
+
 [[package]]
 name = "unicode-segmentation"
 version = "1.13.2"
@@ -5039,6 +5423,18 @@ dependencies = [
  "wasm-bindgen",
 ]
 
+[[package]]
+name = "web_atoms"
+version = "0.2.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "075474b12bcb3d2e3d4546580e9de478eeeead668a1761e2a8860c836b7ef297"
+dependencies = [
+ "phf",
+ "phf_codegen",
+ "string_cache",
+ "string_cache_codegen",
+]
+
 [[package]]
 name = "webpki-root-certs"
 version = "1.0.7"
@@ -5536,6 +5932,12 @@ version = "0.6.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1ffae5123b2d3fc086436f8834ae3ab053a283cfac8fe0a0b8eaae044768a4c4"
 
+[[package]]
+name = "xdg"
+version = "3.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2fb433233f2df9344722454bc7e96465c9d03bff9d77c248f9e7523fe79585b5"
+
 [[package]]
 name = "xz2"
 version = "0.1.7"
@@ -5545,6 +5947,15 @@ dependencies = [
  "lzma-sys",
 ]
 
+[[package]]
+name = "yaml-rust"
+version = "0.4.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "56c1936c4cc7a1c9ab21a1ebb602eb942ba868cbd44a99cb7cdc5892335e1c85"
+dependencies = [
+ "linked-hash-map",
+]
+
 [[package]]
 name = "yaml-rust2"
 version = "0.11.0"
diff --git a/Cargo.toml b/Cargo.toml
index e86be5d..c4fa1ad 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -104,6 +104,10 @@ include_dir = "0.7"
 # Semantic versioning
 semver = "1.0"
 
+# Server-side Markdown rendering (SKILL.md v2 HTML preview) + HTML sanitization
+comrak = "0.54.0"
+ammonia = "4.1.4"
+
 # AWS S3 storage (for registry publishing)
 aws-sdk-s3 = "1"
 aws-config = "1"
diff --git a/crates/fastskill-core/Cargo.toml b/crates/fastskill-core/Cargo.toml
index 61fe45b..bc7a69e 100644
--- a/crates/fastskill-core/Cargo.toml
+++ b/crates/fastskill-core/Cargo.toml
@@ -85,6 +85,10 @@ include_dir.workspace = true
 # Semantic versioning
 semver.workspace = true
 
+# Server-side Markdown rendering (SKILL.md v2 HTML preview) + HTML sanitization
+comrak.workspace = true
+ammonia.workspace = true
+
 [dev-dependencies]
 tempfile.workspace = true
 wiremock = "0.5"
diff --git a/crates/fastskill-core/src/http/handlers/registry.rs b/crates/fastskill-core/src/http/handlers/registry.rs
index 3bc257f..d485f2f 100644
--- a/crates/fastskill-core/src/http/handlers/registry.rs
+++ b/crates/fastskill-core/src/http/handlers/registry.rs
@@ -410,6 +410,63 @@ impl SourceDefinition {
     }
 }
 
+/// GET /api/v1/registry/skills/{id}/versions - Versions available for a skill
+/// id across the configured sources (spec 003 v2 / Phase 4 version picker).
+/// A pure read; always mounted (NOT write-gated). Sourced from
+/// `PackageResolver::get_available_versions`, built over the same
+/// `SourcesManager` the other `/registry/*` browse routes use, and sorted
+/// descending (newest first) by the same semver ordering `VersionConstraint`
+/// uses (unparseable versions sort lowest). No registry configured, or an
+/// unknown id, is an empty `versions` list — a valid answer, never a 404.
+pub async fn list_skill_versions(
+    State(state): State<AppState>,
+    Path(skill_id): Path<String>,
+) -> HttpResult<axum::Json<ApiResponse<SkillVersionsResponse>>> {
+    let empty = || {
+        Json(ApiResponse::success(SkillVersionsResponse {
+            id: skill_id.clone(),
+            versions: Vec::new(),
+        }))
+    };
+
+    let repo_manager = get_repository_manager(&state.service);
+    let (sources_manager, _sources_tmp) = match get_sources_manager_from_repos(&repo_manager).await
+    {
+        Ok(pair) => pair,
+        Err(e) => {
+            tracing::warn!("versions lookup: failed to build sources manager: {}", e);
+            return Ok(empty());
+        }
+    };
+
+    let mut resolver =
+        crate::core::resolver::PackageResolver::new(std::sync::Arc::new(sources_manager));
+    if let Err(e) = resolver.build_index().await {
+        tracing::warn!("versions lookup: failed to build registry index: {}", e);
+        return Ok(empty());
+    }
+
+    let mut candidates = resolver.get_available_versions(&skill_id);
+    candidates.sort_by(|a, b| {
+        semver::Version::parse(&b.version)
+            .ok()
+            .cmp(&semver::Version::parse(&a.version).ok())
+    });
+
+    let versions = candidates
+        .into_iter()
+        .map(|c| VersionInfo {
+            version: c.version.clone(),
+            repo: Some(c.source_name.clone()),
+        })
+        .collect();
+
+    Ok(Json(ApiResponse::success(SkillVersionsResponse {
+        id: skill_id,
+        versions,
+    })))
+}
+
 /// GET /api/v1/registry/index/skills - List all skills from the registry index
 /// Query parameters:
 ///   - scope: Filter by scope (optional)
diff --git a/crates/fastskill-core/src/http/handlers/skills.rs b/crates/fastskill-core/src/http/handlers/skills.rs
index 2499124..8ee9aae 100644
--- a/crates/fastskill-core/src/http/handlers/skills.rs
+++ b/crates/fastskill-core/src/http/handlers/skills.rs
@@ -2,12 +2,14 @@
 
 use crate::core::install::{AddMode, UpdatePreflight};
 use crate::core::manifest::SkillProjectToml;
+use crate::core::origin::Origin;
 use crate::core::service::ServiceError;
+use crate::core::version::VersionConstraint;
 use crate::http::errors::{HttpError, HttpResult};
 use crate::http::handlers::AppState;
 use crate::http::models::*;
 use axum::{
-    extract::{Path, State},
+    extract::{Path, Query, State},
     http::StatusCode,
     Json,
 };
@@ -95,6 +97,7 @@ pub async fn get_skill(
 pub async fn get_skill_content(
     State(state): State<AppState>,
     Path(skill_id): Path<String>,
+    Query(query): Query<ContentQuery>,
 ) -> HttpResult<axum::Json<ApiResponse<SkillContentResponse>>> {
     let skill_id_parsed = crate::core::service::SkillId::new(skill_id.clone())
         .map_err(|_| HttpError::BadRequest("Invalid skill ID format".to_string()))?;
@@ -148,12 +151,29 @@ pub async fn get_skill_content(
         .or_else(|| confined.file_name().map(std::path::PathBuf::from))
         .unwrap_or_else(|| confined.clone());
 
+    let format = query.format.unwrap_or_default();
+    let rendered_content = match format {
+        ContentFormat::Raw => content,
+        ContentFormat::Html => render_skill_markdown_html(&content),
+    };
+
     Ok(axum::Json(ApiResponse::success(SkillContentResponse {
         path: display_path.to_string_lossy().to_string(),
-        content,
+        format: format.as_str().to_string(),
+        content: rendered_content,
     })))
 }
 
+/// Render `SKILL.md` Markdown to sanitized HTML (spec 003 v2 / Phase 4 §5
+/// sanitized preview). Server-side rendering via `comrak` followed by
+/// allowlist sanitization via `ammonia::clean` — the result is safe to assign
+/// to `innerHTML`: no `<script>`, no `on*` handlers, no `javascript:`/`data:`
+/// URLs (ammonia's default strict allowlist strips all three).
+fn render_skill_markdown_html(markdown: &str) -> String {
+    let unsafe_html = comrak::markdown_to_html(markdown, &comrak::Options::default());
+    ammonia::clean(&unsafe_html)
+}
+
 /// DELETE /api/skills/{id} - Delete skill (remove from manifest and storage, unregister)
 pub async fn delete_skill(
     State(state): State<AppState>,
@@ -305,6 +325,66 @@ pub async fn update_skills(
         .skill_id
         .as_deref()
         .filter(|s| !s.is_empty() && *s != "all");
+
+    // Version pin (spec 003 v2 / Phase 4 version picker): only meaningful
+    // together with a single named `skillId`, and only in apply mode — a
+    // `check: true` dry-run reports the ordinary preflight verdict regardless
+    // of `version` (unaffected, per spec).
+    if let Some(version) = payload.version.as_deref() {
+        if !payload.check {
+            let Some(id) = filter_id else {
+                return Err(HttpError::BadRequest(
+                    "`version` requires `skillId` (version pin only applies to a single named \
+                     skill)"
+                        .to_string(),
+                ));
+            };
+            let entry = entries
+                .iter()
+                .find(|e| e.id == id)
+                .ok_or_else(|| HttpError::NotFound(format!("Unknown skill: {}", id)))?;
+
+            let Origin::Repository { repo, skill, .. } = &entry.origin else {
+                return Err(HttpError::BadRequest(format!(
+                    "version pin only applies to repository-origin skills; '{}' is not a \
+                     repository-origin skill",
+                    id
+                )));
+            };
+
+            let constraint = VersionConstraint::parse(version).map_err(|e| {
+                HttpError::BadRequest(format!("Invalid version '{}': {}", version, e))
+            })?;
+            let pinned_origin = Origin::Repository {
+                repo: repo.clone(),
+                skill: skill.clone(),
+                version: Some(constraint),
+            };
+            let groups = entry.groups.clone();
+            let entry_id = entry.id.clone();
+
+            let result = match state
+                .service
+                .add_from_origin(pinned_origin, AddMode::Update, groups)
+                .await
+            {
+                Ok(outcome) => SkillUpdateResult {
+                    id: entry_id,
+                    outcome: "updated".to_string(),
+                    reason: None,
+                    resolved_version: Some(outcome.resolved.version),
+                },
+                Err(e) => SkillUpdateResult {
+                    id: entry_id,
+                    outcome: "error".to_string(),
+                    reason: Some(e.to_string()),
+                    resolved_version: None,
+                },
+            };
+            return Ok(axum::Json(ApiResponse::success(vec![result])));
+        }
+    }
+
     if let Some(id) = filter_id {
         entries.retain(|e| e.id == id);
         if entries.is_empty() {
diff --git a/crates/fastskill-core/src/http/models.rs b/crates/fastskill-core/src/http/models.rs
index e21761b..bdc6a35 100644
--- a/crates/fastskill-core/src/http/models.rs
+++ b/crates/fastskill-core/src/http/models.rs
@@ -273,26 +273,85 @@ pub struct InstallSkillResponse {
 
 /// POST /api/v1/skills/update request body. `skill_id` omitted (or `"all"`)
 /// updates every skill recorded in the project; `check` reports the preflight
-/// verdict for each without applying anything.
+/// verdict for each without applying anything. `version` (v2, spec 003 Phase 4)
+/// pins a single `repository`-origin skill to an exact version: only valid
+/// together with `skill_id` and only when that skill's recorded `Origin` is
+/// `Repository` (see `handlers::skills::update_skills`).
 #[derive(Debug, Deserialize, Clone, Default)]
 #[serde(rename_all = "camelCase")]
 pub struct UpdateSkillsRequest {
     pub skill_id: Option<String>,
     #[serde(default)]
     pub check: bool,
+    pub version: Option<String>,
+}
+
+/// Query parameters for `GET /api/v1/skills/{id}/content`.
+#[derive(Debug, Deserialize, Clone, Default)]
+#[serde(rename_all = "camelCase")]
+pub struct ContentQuery {
+    pub format: Option<ContentFormat>,
+}
+
+/// `?format=` value for `GET /api/v1/skills/{id}/content` (spec 003 v2 / Phase
+/// 4). `Raw` (the default) is today's behavior; `Html` renders the Markdown
+/// server-side (`comrak`) and allowlist-sanitizes the result (`ammonia`) before
+/// returning it — safe to assign to `innerHTML` (no `<script>`, no `on*`
+/// handlers, no `javascript:`/`data:` URLs).
+#[derive(Debug, Deserialize, Clone, Copy, PartialEq, Eq, Default)]
+#[serde(rename_all = "lowercase")]
+pub enum ContentFormat {
+    #[default]
+    Raw,
+    Html,
+}
+
+impl ContentFormat {
+    pub fn as_str(&self) -> &'static str {
+        match self {
+            ContentFormat::Raw => "raw",
+            ContentFormat::Html => "html",
+        }
+    }
 }
 
-/// GET /api/v1/skills/{id}/content response: the installed skill's `SKILL.md`
-/// as raw text (path-confined to the skills directory; see
-/// `handlers::skills::get_skill_content`). Rendered HTML-escaped by the UI —
-/// no Markdown rendering (spec 003 §5 / SEC-7).
+/// GET /api/v1/skills/{id}/content response: the installed skill's `SKILL.md`,
+/// path-confined to the skills directory (see
+/// `handlers::skills::get_skill_content`). `format` echoes the resolved
+/// `?format=` value (`"raw"` or `"html"`); `content` is the raw file text for
+/// `raw`, or sanitized HTML for `html` (spec 003 §5 / SEC-7 — the UI still
+/// HTML-escapes/renders `raw` content itself; `html` content is already safe to
+/// insert directly).
 #[derive(Debug, Serialize, Clone)]
 #[serde(rename_all = "camelCase")]
 pub struct SkillContentResponse {
     pub path: String,
+    pub format: String,
     pub content: String,
 }
 
+/// A single version available for a skill in the registry (spec 003 v2 /
+/// Phase 4 version picker). `repo` is the concrete Repository/source name that
+/// offers this version, when known.
+#[derive(Debug, Serialize, Clone)]
+#[serde(rename_all = "camelCase")]
+pub struct VersionInfo {
+    pub version: String,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub repo: Option<String>,
+}
+
+/// GET /api/v1/registry/skills/{id}/versions response. `versions` is sorted
+/// descending (newest first); empty (not 404) when the registry has no
+/// candidates for `id` (no registry configured, or the id is unknown there) —
+/// see `handlers::registry::list_skill_versions`.
+#[derive(Debug, Serialize, Clone)]
+#[serde(rename_all = "camelCase")]
+pub struct SkillVersionsResponse {
+    pub id: String,
+    pub versions: Vec<VersionInfo>,
+}
+
 /// Per-skill outcome of a `POST /api/v1/skills/update` call.
 #[derive(Debug, Serialize, Clone)]
 #[serde(rename_all = "camelCase")]
diff --git a/crates/fastskill-core/src/http/server.rs b/crates/fastskill-core/src/http/server.rs
index 1a61fc1..4cec66e 100644
--- a/crates/fastskill-core/src/http/server.rs
+++ b/crates/fastskill-core/src/http/server.rs
@@ -295,6 +295,10 @@ impl FastSkillServer {
             .route("/registry/index/skills", get(registry::list_index_skills))
             .route("/registry/sources", get(registry::list_sources))
             .route("/registry/skills", get(registry::list_all_skills))
+            .route(
+                "/registry/skills/{id}/versions",
+                get(registry::list_skill_versions),
+            )
             .route(
                 "/registry/sources/{name}/skills",
                 get(registry::list_source_skills),
diff --git a/crates/fastskill-core/src/http/static/app.js b/crates/fastskill-core/src/http/static/app.js
index f34e592..253374a 100644
--- a/crates/fastskill-core/src/http/static/app.js
+++ b/crates/fastskill-core/src/http/static/app.js
@@ -489,6 +489,21 @@ class FastSkillApp {
               `
             : `<tr><td class="k">origin</td><td class="muted">—</td></tr>`;
 
+        // Version picker (v2): only repository-origin skills carry a version
+        // index to pick from — git/local/zip-url are versionless (spec 003
+        // §3, ADR-0004 scope) and render nothing here.
+        const isRepository = !!(origin && origin.type === 'repository');
+        const versionSection = isRepository
+            ? `
+                <h3 class="drawer-subtitle">Version</h3>
+                <div class="version-picker" id="drawer-version-section">
+                    <select id="drawer-version-select" class="version-select" hidden disabled></select>
+                    <button type="button" id="drawer-version-apply" class="btn btn-secondary" hidden disabled>Apply</button>
+                    <p class="muted" id="drawer-version-note">Loading versions&hellip;</p>
+                </div>
+            `
+            : '';
+
         body.innerHTML = `
             <table class="meta-table"><tbody>
                 <tr><td class="k">id</td><td><code>${this.escapeHtml(skill.id)}</code></td></tr>
@@ -497,33 +512,222 @@ class FastSkillApp {
                 <tr><td class="k">author</td><td>${this.escapeHtml(meta.author || '—')}</td></tr>
                 ${originRows}
             </tbody></table>
+            ${versionSection}
             <h3 class="drawer-subtitle">SKILL.md</h3>
+            <div class="content-toggle" role="group" aria-label="Content view">
+                <button type="button" class="toggle-btn active" id="drawer-format-raw" data-format="raw">Raw</button>
+                <button type="button" class="toggle-btn" id="drawer-format-rendered" data-format="rendered">Rendered</button>
+            </div>
             <pre class="skill-content" id="drawer-content">Loading&hellip;</pre>
+            <div class="markdown-body" id="drawer-content-rendered" hidden></div>
         `;
 
         drawer.classList.add('open');
         drawer.setAttribute('aria-hidden', 'false');
         this._openSkillId = skill.id;
+        // format -> fetched content, so toggling Raw/Rendered back and forth
+        // doesn't refetch on every click.
+        this._contentCache = { raw: null, rendered: null };
+
+        const rawBtn = document.getElementById('drawer-format-raw');
+        const renderedBtn = document.getElementById('drawer-format-rendered');
+        if (rawBtn) rawBtn.addEventListener('click', () => this.setContentFormat(skill.id, 'raw'));
+        if (renderedBtn) renderedBtn.addEventListener('click', () => this.setContentFormat(skill.id, 'rendered'));
+
+        if (isRepository) {
+            const versionApplyBtn = document.getElementById('drawer-version-apply');
+            if (versionApplyBtn) versionApplyBtn.addEventListener('click', () => this.applyVersionChange(skill));
+            this.loadVersionPicker(skill);
+        }
+
+        // Raw is selected by default (unchanged v1 behavior).
+        this.setContentFormat(skill.id, 'raw');
+    }
+
+    // Switches the drawer's SKILL.md view between the escaped raw <pre> and
+    // the server-rendered/sanitized markdown container, fetching content for
+    // that format on first use and reusing the cache afterward.
+    setContentFormat(skillId, format) {
+        this._contentFormat = format;
+        const rawBtn = document.getElementById('drawer-format-raw');
+        const renderedBtn = document.getElementById('drawer-format-rendered');
+        const contentEl = document.getElementById('drawer-content');
+        const renderedEl = document.getElementById('drawer-content-rendered');
+        if (rawBtn) rawBtn.classList.toggle('active', format === 'raw');
+        if (renderedBtn) renderedBtn.classList.toggle('active', format === 'rendered');
+        if (contentEl) contentEl.hidden = format !== 'raw';
+        if (renderedEl) renderedEl.hidden = format !== 'rendered';
+        this.loadDrawerContent(skillId, format);
+    }
+
+    async loadDrawerContent(skillId, format) {
+        const cache = this._contentCache || (this._contentCache = { raw: null, rendered: null });
+        if (cache[format] != null) {
+            this.applyContentToDom(format, cache[format]);
+            return;
+        }
+
+        const contentEl = document.getElementById('drawer-content');
+        const renderedEl = document.getElementById('drawer-content-rendered');
+        if (format === 'raw') {
+            if (contentEl) contentEl.textContent = 'Loading…';
+        } else if (renderedEl) {
+            renderedEl.textContent = 'Loading…';
+        }
 
         try {
-            const res = await fetch(`${this.apiBase}/skills/${encodeURIComponent(skill.id)}/content`);
+            const url = format === 'rendered'
+                ? `${this.apiBase}/skills/${encodeURIComponent(skillId)}/content?format=html`
+                : `${this.apiBase}/skills/${encodeURIComponent(skillId)}/content`;
+            const res = await fetch(url);
             const data = await res.json().catch(() => null);
             // The drawer may have been closed/reopened on a different skill
             // while this request was in flight.
-            if (this._openSkillId !== skill.id) return;
-            const contentEl = document.getElementById('drawer-content');
-            if (!contentEl) return;
+            if (this._openSkillId !== skillId) return;
+
             if (res.ok && data && data.success && data.data) {
-                // textContent, not innerHTML: the SKILL.md body is untrusted
-                // content (SEC-7) and must never be interpreted as markup.
-                contentEl.textContent = data.data.content != null ? data.data.content : '';
+                const value = data.data.content != null ? data.data.content : '';
+                cache[format] = value;
+                this.applyContentToDom(format, value);
             } else {
-                contentEl.textContent = `Error loading content: ${(data && data.error && data.error.message) || res.status}`;
+                const msg = `Error loading content: ${(data && data.error && data.error.message) || res.status}`;
+                if (format === 'raw') { if (contentEl) contentEl.textContent = msg; }
+                else if (renderedEl) renderedEl.textContent = msg;
             }
         } catch (err) {
+            if (this._openSkillId !== skillId) return;
+            const msg = `Error: ${err.message}`;
+            if (format === 'raw') { if (contentEl) contentEl.textContent = msg; }
+            else if (renderedEl) renderedEl.textContent = msg;
+        }
+    }
+
+    applyContentToDom(format, value) {
+        const contentEl = document.getElementById('drawer-content');
+        const renderedEl = document.getElementById('drawer-content-rendered');
+        if (format === 'raw') {
+            if (!contentEl) return;
+            // textContent, not innerHTML: the SKILL.md raw body is untrusted
+            // content (SEC-7) and must never be interpreted as markup.
+            contentEl.textContent = value;
+            return;
+        }
+        if (!renderedEl) return;
+        // INTENTIONAL innerHTML, NOT a SEC-7 violation: `value` here is the
+        // *rendered* markdown response (`?format=html`), which the Rust
+        // server already ran through comrak + an ammonia allowlist
+        // sanitizer before sending it — it is not the raw untrusted
+        // SKILL.md text. Re-escaping it here would print literal `<h1>`
+        // tags as text instead of rendering them. Do NOT change this to
+        // textContent/escapeHtml; if you need to distrust this value, fix
+        // the sanitization server-side instead.
+        renderedEl.innerHTML = value;
+        // Extra client-side safety net on top of server sanitization: force
+        // every link to open in a new tab without leaking a window.opener
+        // handle back to the linked page. Operates on the already-sanitized
+        // DOM (not on raw untrusted text), so this is safe regardless of
+        // what the server did or didn't set.
+        renderedEl.querySelectorAll('a[href]').forEach((a) => {
+            a.setAttribute('target', '_blank');
+            a.setAttribute('rel', 'noopener noreferrer');
+        });
+    }
+
+    // ---- version picker (repository-origin skills only) -------------------
+
+    async loadVersionPicker(skill) {
+        const section = document.getElementById('drawer-version-section');
+        if (!section) return;
+
+        const select = document.getElementById('drawer-version-select');
+        const applyBtn = document.getElementById('drawer-version-apply');
+        const note = document.getElementById('drawer-version-note');
+        const writable = !!(this.status && this.status.writable);
+
+        try {
+            const res = await fetch(`${this.apiBase}/registry/skills/${encodeURIComponent(skill.id)}/versions`);
+            const data = await res.json().catch(() => null);
             if (this._openSkillId !== skill.id) return;
-            const contentEl = document.getElementById('drawer-content');
-            if (contentEl) contentEl.textContent = `Error: ${err.message}`;
+
+            const versions = (res.ok && data && data.success && data.data && Array.isArray(data.data.versions))
+                ? data.data.versions
+                : [];
+
+            if (versions.length === 0) {
+                if (select) select.hidden = true;
+                if (applyBtn) applyBtn.hidden = true;
+                if (note) {
+                    note.hidden = false;
+                    note.textContent = 'No other versions available';
+                }
+                return;
+            }
+
+            const meta = skill.metadata || {};
+            const origin = meta.origin || {};
+            const current = origin.version || meta.version || null;
+
+            if (select) {
+                select.innerHTML = versions.map((v) => {
+                    const val = this.escapeHtml(v.version);
+                    const selected = current && v.version === current ? ' selected' : '';
+                    return `<option value="${val}"${selected}>${val}</option>`;
+                }).join('');
+                select.disabled = !writable;
+                select.hidden = false;
+            }
+            if (applyBtn) {
+                applyBtn.disabled = !writable;
+                applyBtn.hidden = false;
+            }
+            if (note) note.hidden = true;
+        } catch (err) {
+            if (this._openSkillId !== skill.id) return;
+            if (select) select.hidden = true;
+            if (applyBtn) applyBtn.hidden = true;
+            if (note) {
+                note.hidden = false;
+                note.textContent = `Error loading versions: ${err.message}`;
+            }
+        }
+    }
+
+    async applyVersionChange(skill) {
+        if (!(this.status && this.status.writable)) {
+            this.toast('Read-only — start with --enable-write to update skills', 'error');
+            return;
+        }
+
+        const select = document.getElementById('drawer-version-select');
+        const applyBtn = document.getElementById('drawer-version-apply');
+        if (!select || !select.value) return;
+
+        if (applyBtn) { applyBtn.disabled = true; applyBtn.textContent = 'Applying…'; }
+        try {
+            const res = await fetch(`${this.apiBase}/skills/update`, {
+                method: 'POST',
+                headers: { 'Content-Type': 'application/json' },
+                body: JSON.stringify({ skillId: skill.id, version: select.value }),
+            });
+            const data = await res.json().catch(() => null);
+            if (res.ok && data && data.success && Array.isArray(data.data)) {
+                this.toast(this.summarizeUpdateResults(data.data), 'success');
+                await this.loadAll();
+                // Refresh the drawer in place so metadata/version reflect
+                // the just-applied change, if the skill is still installed.
+                const refreshed = this.skills.find((s) => s.id === skill.id);
+                if (refreshed) await this.openDrawer(refreshed);
+            } else if (res.status === 403) {
+                this.toast('Read-only — start with --enable-write to update skills', 'error');
+            } else {
+                this.toast((data && data.error && data.error.message) || 'Version update failed', 'error');
+            }
+        } catch (err) {
+            this.toast(`Error: ${err.message}`, 'error');
+        } finally {
+            // No-op if openDrawer already replaced the drawer body above.
+            const btn = document.getElementById('drawer-version-apply');
+            if (btn) { btn.disabled = !(this.status && this.status.writable); btn.textContent = 'Apply'; }
         }
     }
 
@@ -533,6 +737,7 @@ class FastSkillApp {
         drawer.classList.remove('open');
         drawer.setAttribute('aria-hidden', 'true');
         this._openSkillId = null;
+        this._contentCache = null;
     }
 
     // ---- toasts -----------------------------------------------------------
diff --git a/crates/fastskill-core/src/http/static/styles.css b/crates/fastskill-core/src/http/static/styles.css
index 448b9a8..1867c3a 100644
--- a/crates/fastskill-core/src/http/static/styles.css
+++ b/crates/fastskill-core/src/http/static/styles.css
@@ -448,6 +448,160 @@ body {
     overflow-y: auto;
 }
 
+/* ---- Content format toggle (Raw / Rendered) ---- */
+
+.content-toggle {
+    display: flex;
+    gap: 4px;
+    margin-bottom: 8px;
+}
+
+.toggle-btn {
+    padding: 5px 12px;
+    font-size: 0.8125rem;
+    font-weight: 500;
+    border: 1px solid #dee2e6;
+    background: #fff;
+    color: #495057;
+    cursor: pointer;
+    border-radius: 4px;
+}
+
+.toggle-btn:hover {
+    background: #f1f3f5;
+}
+
+.toggle-btn.active {
+    background: #eef0fb;
+    border-color: #5c6bc0;
+    color: #3f51b5;
+}
+
+/* ---- Rendered SKILL.md (server-sanitized HTML) ---- */
+
+.markdown-body {
+    font-size: 0.875rem;
+    line-height: 1.6;
+    background: #f8f9fa;
+    border: 1px solid #e9ecef;
+    border-radius: 6px;
+    padding: 12px 16px;
+    max-height: 60vh;
+    overflow-y: auto;
+    word-wrap: break-word;
+}
+
+.markdown-body h1,
+.markdown-body h2,
+.markdown-body h3,
+.markdown-body h4 {
+    margin: 16px 0 8px;
+    font-weight: 600;
+    line-height: 1.3;
+}
+
+.markdown-body h1:first-child,
+.markdown-body h2:first-child,
+.markdown-body h3:first-child {
+    margin-top: 0;
+}
+
+.markdown-body p {
+    margin: 8px 0;
+}
+
+.markdown-body ul,
+.markdown-body ol {
+    margin: 8px 0 8px 20px;
+}
+
+.markdown-body li {
+    margin: 2px 0;
+}
+
+.markdown-body code {
+    font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
+    font-size: 0.8125rem;
+    background: #f1f3f5;
+    padding: 1px 5px;
+    border-radius: 3px;
+}
+
+.markdown-body pre {
+    background: #f1f3f5;
+    border-radius: 6px;
+    padding: 10px 12px;
+    overflow-x: auto;
+    margin: 8px 0;
+}
+
+.markdown-body pre code {
+    background: none;
+    padding: 0;
+}
+
+.markdown-body blockquote {
+    margin: 8px 0;
+    padding: 4px 12px;
+    border-left: 3px solid #dee2e6;
+    color: #6c757d;
+}
+
+.markdown-body table {
+    border-collapse: collapse;
+    margin: 8px 0;
+    width: 100%;
+}
+
+.markdown-body th,
+.markdown-body td {
+    border: 1px solid #e9ecef;
+    padding: 6px 10px;
+    text-align: left;
+}
+
+.markdown-body th {
+    background: #f1f3f5;
+    font-weight: 600;
+}
+
+.markdown-body a {
+    color: #5c6bc0;
+    text-decoration: none;
+}
+
+.markdown-body a:hover {
+    text-decoration: underline;
+}
+
+.markdown-body hr {
+    border: none;
+    border-top: 1px solid #e9ecef;
+    margin: 16px 0;
+}
+
+.markdown-body img {
+    max-width: 100%;
+}
+
+/* ---- Version picker (repository-origin skills only) ---- */
+
+.version-picker {
+    display: flex;
+    align-items: center;
+    gap: 8px;
+    flex-wrap: wrap;
+    margin-bottom: 8px;
+}
+
+.version-select {
+    padding: 6px 10px;
+    border: 1px solid #dee2e6;
+    border-radius: 4px;
+    font-size: 0.8125rem;
+    min-width: 140px;
+}
+
 /* ---- Toasts ---- */
 
 .toast-container {
diff --git a/crates/fastskill-core/tests/http_handler_route_tests.rs b/crates/fastskill-core/tests/http_handler_route_tests.rs
index 7429a17..d134c7f 100644
--- a/crates/fastskill-core/tests/http_handler_route_tests.rs
+++ b/crates/fastskill-core/tests/http_handler_route_tests.rs
@@ -212,6 +212,10 @@ fn router(state: AppState) -> Router {
         .route("/reindex/{id}", post(reindex::reindex_skill))
         .route("/registry/sources", get(registry::list_sources))
         .route("/registry/skills", get(registry::list_all_skills))
+        .route(
+            "/registry/skills/{id}/versions",
+            get(registry::list_skill_versions),
+        )
         .route("/registry/index/skills", get(registry::list_index_skills))
         .route(
             "/registry/sources/{name}/skills",
@@ -361,6 +365,46 @@ async fn get_skill_content_traversal_attempt_is_rejected() {
     );
 }
 
+#[tokio::test]
+async fn get_skill_content_format_raw_explicit_matches_default() {
+    let f = fixture_for_content().await;
+    let (status, body) = do_get(f.state, "/skills/alpha-skill/content?format=raw").await;
+    assert_eq!(status, StatusCode::OK, "body: {body}");
+    assert!(body.contains("\"format\":\"raw\""), "body: {body}");
+    assert!(body.contains("Alpha Skill"), "body: {body}");
+}
+
+#[tokio::test]
+async fn get_skill_content_format_html_renders_and_sanitizes_malicious_payload() {
+    // Spec 003 v2: `?format=html` renders SKILL.md through comrak then
+    // sanitizes with ammonia -- a <script>, an onerror handler, and a
+    // javascript: URL embedded in the body must all be stripped from the
+    // returned HTML.
+    let f = fixture_for_content().await;
+    let skill_file = f.state.skills_directory.join("alpha-skill/SKILL.md");
+    fs::write(
+        &skill_file,
+        "---\nname: Alpha Skill\ndescription: First test skill\nversion: 1.0.0\n---\n\
+         # Alpha\n\n<script>alert('xss')</script>\n\n\
+         <img src=\"x\" onerror=\"alert(1)\">\n\n\
+         [click me](javascript:alert(1))\n",
+    )
+    .unwrap();
+
+    let (status, body) = do_get(f.state, "/skills/alpha-skill/content?format=html").await;
+    assert_eq!(status, StatusCode::OK, "body: {body}");
+    assert!(body.contains("\"format\":\"html\""), "body: {body}");
+    assert!(!body.contains("<script"), "script tag leaked: {body}");
+    assert!(!body.contains("alert("), "script content leaked: {body}");
+    assert!(!body.contains("onerror"), "event handler leaked: {body}");
+    assert!(
+        !body.contains("javascript:"),
+        "javascript: URL leaked: {body}"
+    );
+    // Something was actually rendered (the safe heading text survives).
+    assert!(body.contains("Alpha"), "body: {body}");
+}
+
 #[tokio::test]
 async fn delete_skill_invalid_id_is_400() {
     let f = fixture_with_skills(true).await;
@@ -525,6 +569,201 @@ async fn update_upgrade_alias_route_behaves_identically() {
     assert!(body.contains("\"data\":[]"), "body: {body}");
 }
 
+// ---- version-pinned update (spec 003 v2 / Phase 4 version picker) ----
+
+#[tokio::test]
+async fn update_version_without_skill_id_is_400() {
+    let f = fixture_for_install(true).await;
+    let (status, body) = post_json(
+        f.state,
+        "/skills/update",
+        serde_json::json!({"version": "2.0.0"}),
+    )
+    .await;
+    assert_eq!(status, StatusCode::BAD_REQUEST, "body: {body}");
+}
+
+#[tokio::test]
+async fn update_version_with_all_skill_id_is_400() {
+    // "all" is the sentinel for "every skill" -- not a single named skill.
+    let f = fixture_for_install(true).await;
+    let (status, body) = post_json(
+        f.state,
+        "/skills/update",
+        serde_json::json!({"skillId": "all", "version": "2.0.0"}),
+    )
+    .await;
+    assert_eq!(status, StatusCode::BAD_REQUEST, "body: {body}");
+}
+
+#[tokio::test]
+async fn update_version_non_repository_origin_is_400() {
+    let f = fixture_for_install(true).await;
+    fs::write(
+        &f.project_file_path,
+        "[dependencies]\nlocaldep = { origin = { type = \"local\", path = \"/tmp/x\" } }\n",
+    )
+    .unwrap();
+    let (status, body) = post_json(
+        f.state,
+        "/skills/update",
+        serde_json::json!({"skillId": "localdep", "version": "2.0.0"}),
+    )
+    .await;
+    assert_eq!(status, StatusCode::BAD_REQUEST, "body: {body}");
+}
+
+#[tokio::test]
+async fn update_version_check_mode_ignores_version() {
+    // `check: true` reports the ordinary preflight verdict regardless of
+    // `version` -- an unaffected dry-run must not 400 even without `skillId`.
+    let f = fixture_for_install(true).await;
+    let (status, body) = post_json(
+        f.state,
+        "/skills/update",
+        serde_json::json!({"check": true, "version": "2.0.0"}),
+    )
+    .await;
+    assert_eq!(status, StatusCode::OK, "body: {body}");
+}
+
+fn build_zip_with_skill_md(skill_dir_name: &str, skill_md: &str) -> Vec<u8> {
+    use std::io::Write;
+    use zip::write::FileOptions;
+    let mut buf = Vec::new();
+    {
+        let cursor = std::io::Cursor::new(&mut buf);
+        let mut writer = zip::ZipWriter::new(cursor);
+        let opts = FileOptions::default().compression_method(zip::CompressionMethod::Stored);
+        writer
+            .start_file(format!("{skill_dir_name}/SKILL.md"), opts)
+            .unwrap();
+        writer.write_all(skill_md.as_bytes()).unwrap();
+        writer.finish().unwrap();
+    }
+    buf
+}
+
+#[tokio::test]
+async fn update_version_pin_happy_path_repository_origin() {
+    use fastskill_core::core::registry::client::IndexEntry;
+    use fastskill_core::core::repository::{
+        RepositoryConfig, RepositoryDefinition, RepositoryManager, RepositoryType,
+    };
+    use sha2::Digest;
+    use wiremock::{
+        matchers::{method, path},
+        Mock, MockServer, ResponseTemplate,
+    };
+
+    let storage = TempDir::new().unwrap();
+    let store = skills_root(&storage);
+    let project = TempDir::new().unwrap();
+    let project_file_path = project.path().join("skill-project.toml");
+    fs::write(
+        &project_file_path,
+        format!(
+            "[tool.fastskill]\nskills_directory = \"{}\"\n\n[dependencies]\n\
+             widget = {{ origin = {{ type = \"repository\", repo = \"myreg\", skill = \"widget\" }} }}\n",
+            store.display()
+        ),
+    )
+    .unwrap();
+
+    let server = MockServer::start().await;
+    let zip_bytes = build_zip_with_skill_md(
+        "widget",
+        "---\nname: widget\nversion: \"2.0.0\"\ndescription: A registry skill\n---\nBody\n",
+    );
+    let cksum = format!("sha256:{:x}", sha2::Sha256::digest(&zip_bytes));
+
+    let entries = [
+        IndexEntry {
+            name: "widget".to_string(),
+            vers: "1.0.0".to_string(),
+            deps: vec![],
+            cksum: "sha256:0".to_string(),
+            features: std::collections::HashMap::new(),
+            yanked: false,
+            links: None,
+            download_url: format!("{}/dl/1.0.0", server.uri()),
+            metadata: None,
+        },
+        IndexEntry {
+            name: "widget".to_string(),
+            vers: "2.0.0".to_string(),
+            deps: vec![],
+            cksum,
+            features: std::collections::HashMap::new(),
+            yanked: false,
+            links: None,
+            download_url: format!("{}/dl/2.0.0", server.uri()),
+            metadata: None,
+        },
+    ];
+    let body = entries
+        .iter()
+        .map(|e| serde_json::to_string(e).unwrap())
+        .collect::<Vec<_>>()
+        .join("\n");
+
+    Mock::given(method("GET"))
+        .and(path("/index/widget"))
+        .respond_with(ResponseTemplate::new(200).set_body_string(body))
+        .mount(&server)
+        .await;
+    Mock::given(method("GET"))
+        .and(path("/dl/2.0.0"))
+        .respond_with(ResponseTemplate::new(200).set_body_bytes(zip_bytes))
+        .mount(&server)
+        .await;
+
+    let repo_manager = RepositoryManager::from_definitions(vec![RepositoryDefinition {
+        name: "myreg".to_string(),
+        repo_type: RepositoryType::HttpRegistry,
+        priority: 0,
+        config: RepositoryConfig::HttpRegistry {
+            index_url: format!("{}/index", server.uri()),
+        },
+        auth: None,
+        storage: None,
+    }]);
+
+    let config = ServiceConfig {
+        skill_storage_path: store.clone(),
+        ..Default::default()
+    };
+    let mut svc = FastSkillService::new(config).await.unwrap();
+    svc.initialize().await.unwrap();
+    let svc = svc
+        .with_project_root(project.path().to_path_buf())
+        .with_repository_manager(Arc::new(repo_manager));
+    let service = Arc::new(svc);
+
+    let mut state = AppState::new(service).unwrap();
+    state.project_file_path = project_file_path.clone();
+    state.project_root = project.path().to_path_buf();
+    state.skills_directory = store;
+    state.enable_write = true;
+
+    let (status, body) = post_json(
+        state,
+        "/skills/update",
+        serde_json::json!({"skillId": "widget", "version": "2.0.0"}),
+    )
+    .await;
+    assert_eq!(status, StatusCode::OK, "body: {body}");
+    assert!(body.contains("\"outcome\":\"updated\""), "body: {body}");
+    assert!(
+        body.contains("\"resolvedVersion\":\"2.0.0\""),
+        "body: {body}"
+    );
+
+    // The manifest now records the exact pin, not the original unconstrained origin.
+    let saved = fs::read_to_string(&project_file_path).unwrap();
+    assert!(saved.contains("=2.0.0"), "manifest: {saved}");
+}
+
 // ---------------------------------------------------------------------------
 // status.rs (status endpoint + root dashboard incl. SEC-7 escaping)
 // ---------------------------------------------------------------------------
@@ -933,6 +1172,101 @@ async fn registry_marketplace_unknown_is_404() {
     assert_eq!(status, StatusCode::NOT_FOUND);
 }
 
+// ---- list_skill_versions (spec 003 v2 / Phase 4 version picker) ----
+
+#[tokio::test]
+#[allow(clippy::await_holding_lock)]
+async fn registry_skill_versions_empty_when_no_registry_configured() {
+    // No skill-project.toml with `[[tool.fastskill.repositories]]` reachable
+    // from cwd -> no sources -> empty `versions`, still 200 (never 404).
+    // `get_repository_manager` resolves off the process cwd, which is shared
+    // process-wide state; hold `DIR_MUTEX` so this can't race the other
+    // `registry_skill_versions_*` tests that `set_current_dir` into a temp
+    // project with repositories configured.
+    let _lock = fastskill_core::test_utils::DIR_MUTEX
+        .lock()
+        .unwrap_or_else(|e| e.into_inner());
+    let f = fixture_with_skills(false).await;
+    let (status, body) = do_get(f.state, "/registry/skills/widget/versions").await;
+    assert_eq!(status, StatusCode::OK, "body: {body}");
+    assert!(body.contains("\"id\":\"widget\""), "body: {body}");
+    assert!(body.contains("\"versions\":[]"), "body: {body}");
+}
+
+#[tokio::test]
+#[allow(clippy::await_holding_lock)]
+async fn registry_skill_versions_unknown_id_is_empty_not_404() {
+    let _lock = fastskill_core::test_utils::DIR_MUTEX
+        .lock()
+        .unwrap_or_else(|e| e.into_inner());
+    let original_dir = std::env::current_dir().ok();
+    let _guard = fastskill_core::test_utils::DirGuard(original_dir);
+
+    let project = TempDir::new().unwrap();
+    let repo_dir = TempDir::new().unwrap();
+    write_skill(repo_dir.path(), "known", "Known", "d");
+    fs::write(
+        project.path().join("skill-project.toml"),
+        format!(
+            "[dependencies]\n\n[[tool.fastskill.repositories]]\nname = \"localrepo\"\ntype = \"local\"\npath = \"{}\"\npriority = 0\n",
+            repo_dir.path().display()
+        ),
+    )
+    .unwrap();
+    std::env::set_current_dir(project.path()).unwrap();
+
+    let f = fixture_with_skills(false).await;
+    let (status, body) = do_get(f.state, "/registry/skills/does-not-exist/versions").await;
+    assert_eq!(status, StatusCode::OK, "body: {body}");
+    assert!(body.contains("\"versions\":[]"), "body: {body}");
+}
+
+#[tokio::test]
+#[allow(clippy::await_holding_lock)]
+async fn registry_skill_versions_populated_and_sorted_descending() {
+    let _lock = fastskill_core::test_utils::DIR_MUTEX
+        .lock()
+        .unwrap_or_else(|e| e.into_inner());
+    let original_dir = std::env::current_dir().ok();
+    let _guard = fastskill_core::test_utils::DirGuard(original_dir);
+
+    let project = TempDir::new().unwrap();
+    let repo_dir = TempDir::new().unwrap();
+    // Two versions of the same skill id, in separate subdirectories, discovered
+    // by the local-source scanner (walks for any nested SKILL.md).
+    for (subdir, version) in [("v1", "1.0.0"), ("v9", "1.9.0"), ("v10", "1.10.0")] {
+        let dir = repo_dir.path().join(subdir);
+        fs::create_dir_all(&dir).unwrap();
+        fs::write(
+            dir.join("SKILL.md"),
+            format!("---\nid: widget\nname: widget\nversion: {version}\ndescription: d\n---\n"),
+        )
+        .unwrap();
+    }
+    fs::write(
+        project.path().join("skill-project.toml"),
+        format!(
+            "[dependencies]\n\n[[tool.fastskill.repositories]]\nname = \"localrepo\"\ntype = \"local\"\npath = \"{}\"\npriority = 0\n",
+            repo_dir.path().display()
+        ),
+    )
+    .unwrap();
+    std::env::set_current_dir(project.path()).unwrap();
+
+    let f = fixture_with_skills(false).await;
+    let (status, body) = do_get(f.state, "/registry/skills/widget/versions").await;
+    assert_eq!(status, StatusCode::OK, "body: {body}");
+    assert!(body.contains("\"id\":\"widget\""), "body: {body}");
+    // Descending, semver-correct (not string) order: 1.10.0 before 1.9.0 before 1.0.0.
+    let pos_10 = body.find("1.10.0").expect("1.10.0 present");
+    let pos_9 = body.find("1.9.0").expect("1.9.0 present");
+    let pos_1 = body.find("1.0.0").expect("1.0.0 present");
+    assert!(
+        pos_10 < pos_9 && pos_9 < pos_1,
+        "expected descending semver order: {body}"
+    );
+}
+
 // ---- registry index (list_index_skills) ----
 
 async fn state_with_registry(registry: &TempDir) -> AppState {