diff --git a/CHANGELOG.md b/CHANGELOG.md
index cda3a58..c187430 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,15 @@
 # Changelog
 
+## v0.22.0
+
+### Added
+
+- **Seed lists on `similar` and `sfxSimilar`** — pass a list instead of one asset (`AudioScape:similar(playlist.tracks, { limit = 20 })`, or `{ asset_ids = { ... }, limit = 20 }`) and results sound like the set as a whole rather than any one track: playlist continuation for music, variety packs for SFX. Each element can be anything the single-seed form accepts (asset_id string, Track, `Sound`, `AudioPlayer`); up to 100 seeds; seeds are never returned. `result.meta.seeds_used` counts the seeds that resolved and `result.meta.seeds_ignored` lists the ids skipped (unknown, not yet analyzed, or not public). Available through `AudioScapeClient.similar` / `sfxSimilar` too.
+
+### Fixed
+
+- **`AudioScapeClient.similar` and `sfxSimilar` now honour `max_score` and `dedupe`.** The client methods sent both, but the server-side remotes dropped them before calling the API, so near-duplicate filtering never applied to client-initiated calls.
+
 ## v0.21.0
 
 ### Changed
diff --git a/README.md b/README.md
index f880b98..cae718d 100644
--- a/README.md
+++ b/README.md
@@ -12,7 +12,7 @@ Add to your `wally.toml`:
 
 ```toml
 [server-dependencies]
-AudioScape = "this-fifo/audioscape-sdk@0.21.0"
+AudioScape = "this-fifo/audioscape-sdk@0.22.0"
 ```
 
 Then run:
@@ -168,7 +168,8 @@ local result, err = AudioScape:lookup({
 
 Find tracks that sound similar to a given track. `input` is anything that
 carries an asset_id — a string, a Track from a previous response, a `Sound`,
-or an `AudioPlayer`.
+or an `AudioPlayer` — or a list of those (up to 100), in which case results
+sound like the set as a whole.
 
 ```lua
 local result, err = AudioScape:similar({
@@ -188,6 +189,13 @@ local result = AudioScape:similar(playlist.tracks[1], { limit = 10 })
 
 -- Shorthand: pass a playing Sound directly
 local result = AudioScape:similar(soundInstance)
+
+-- Playlist continuation: pass a list (strings, Tracks, Sounds) and get
+-- tracks that sound like the whole set. Seeds are never returned; page with
+-- `offset` to build the next playlist.
+local result = AudioScape:similar(playlist.tracks, { limit = 20 })
+-- result.meta.seeds_used     -- seeds that resolved and were blended
+-- result.meta.seeds_ignored  -- ids skipped: unknown, not yet analyzed, or not public
 ```
 
 ### `AudioScape:browse(options)`
@@ -291,7 +299,8 @@ local result, err = AudioScape:sfxSearch({
 ### `AudioScape:sfxSimilar(input, extras?)`
 
 Find sound effects acoustically similar to a given asset. Same polymorphic
-input as `AudioScape:similar`.
+input as `AudioScape:similar`, including a list of seeds to grow a variety
+pack from the clips you already picked.
 
 ```lua
 local result, err = AudioScape:sfxSimilar({
@@ -308,6 +317,9 @@ local result, err = AudioScape:sfxSimilar({
 
 -- Or pass an SfxTrack / Sound / asset_id string:
 local result = AudioScape:sfxSimilar(sfx.tracks[1], { limit = 10 })
+
+-- Or a list of seeds — results sound like the set as a whole:
+local result = AudioScape:sfxSimilar({ "9083837523", "18672006515" }, { limit = 10 })
 ```
 
 ### `AudioScape:getSfxTaxonomy()`
diff --git a/src/AudioScapeClient.luau b/src/AudioScapeClient.luau
index 5ed8087..3c0ee00 100644
--- a/src/AudioScapeClient.luau
+++ b/src/AudioScapeClient.luau
@@ -38,6 +38,11 @@ end
 -- beyond asset_id) typecheck under strict mode.
 export type AssetIdResolvable = string | { asset_id: string, [string]: any } | Sound | AudioPlayer
 
+-- Seed-list forms of similar / sfxSimilar (mirrors src/init.luau): an array
+-- of AssetIdResolvable, or an options table carrying `asset_ids`.
+export type SeedList = { AssetIdResolvable }
+export type SimilarInput = AssetIdResolvable | SeedList | { asset_ids: SeedList, [string]: any }
+
 type AudioScapeClientInstance = typeof(setmetatable(
 	{} :: {
 		-- Optional because the module itself starts unresolved and fills this
@@ -110,6 +115,35 @@ local function resolveAssetId(input: any): string?
 	return nil
 end
 
+-- Mirrored from src/init.luau (see resolveSeedIds there): (nil, nil) when
+-- `input` is not a seed list, (nil, reason) when an element doesn't resolve,
+-- (ids, nil) otherwise.
+local function resolveSeedIds(input: any): ({ string }?, string?)
+	if type(input) ~= "table" or input.asset_id ~= nil then
+		return nil, nil
+	end
+	local list: any
+	if type(input.asset_ids) == "table" then
+		list = input.asset_ids
+	elseif #input > 0 then
+		list = input
+	else
+		return nil, nil
+	end
+	local ids: { string } = {}
+	for i, item in ipairs(list) do
+		local id = resolveAssetId(item)
+		if not id then
+			return nil, string.format("asset_ids[%d] is not an asset_id string, a track table, a Sound, or an AudioPlayer", i)
+		end
+		table.insert(ids, id)
+	end
+	if #ids == 0 then
+		return nil, "asset_ids must be a non-empty list"
+	end
+	return ids, nil
+end
+
 -- Search the catalog. Pass `query` for free-text/natural-language search, or
 -- `asset_ids` for a direct batch lookup of up to 100 IDs (filters bypassed,
 -- results in input order, missing IDs surfaced in `meta.missing_ids`).
@@ -138,13 +172,14 @@ function AudioScapeClient.lookup(self: AudioScapeClientInstance, options: { asse
 end
 
 -- Find tracks that sound similar to a given track. Polymorphic input —
--- pass an asset_id string, a Track table, a Sound, or an AudioPlayer; pass
--- `extras` when you want limit/offset/filters and didn't use the legacy
--- options-table form. `max_score`/`dedupe` filter near-duplicate matches
--- of the seed track from the results.
+-- pass an asset_id string, a Track table, a Sound, or an AudioPlayer, or a
+-- list of those to get tracks that sound like the whole set; pass `extras`
+-- when you want limit/offset/filters and didn't use the legacy options-table
+-- form. `max_score`/`dedupe` filter near-duplicate matches of the seed track
+-- from the results.
 function AudioScapeClient.similar(
 	self: AudioScapeClientInstance,
-	input: AssetIdResolvable,
+	input: SimilarInput,
 	extras: {
 		limit: number?,
 		offset: number?,
@@ -153,13 +188,18 @@ function AudioScapeClient.similar(
 		dedupe: boolean?,
 	}?
 ): (any, string?)
-	local assetId = resolveAssetId(input)
-	if not assetId then
-		return nil, "similar requires an asset_id string, a track table, a Sound, or an AudioPlayer"
+	local seedIds, seedErr = resolveSeedIds(input)
+	if seedErr then
+		return nil, "similar " .. seedErr
+	end
+	local assetId = if seedIds then nil else resolveAssetId(input)
+	if not seedIds and not assetId then
+		return nil, "similar requires an asset_id string, a track table, a Sound, or an AudioPlayer, or a list of them"
 	end
 	local opts: any = extras or (type(input) == "table" and input or {})
 	return invoke(getRemotes(self), "Similar", {
 		asset_id = assetId,
+		asset_ids = seedIds,
 		limit = opts.limit,
 		offset = opts.offset,
 		filters = opts.filters,
@@ -182,7 +222,7 @@ end
 -- SFX libraries with many uploads of the same generic clip.
 function AudioScapeClient.sfxSimilar(
 	self: AudioScapeClientInstance,
-	input: AssetIdResolvable,
+	input: SimilarInput,
 	extras: {
 		limit: number?,
 		offset: number?,
@@ -191,13 +231,18 @@ function AudioScapeClient.sfxSimilar(
 		dedupe: boolean?,
 	}?
 ): (any, string?)
-	local assetId = resolveAssetId(input)
-	if not assetId then
-		return nil, "sfxSimilar requires an asset_id string, a track table, a Sound, or an AudioPlayer"
+	local seedIds, seedErr = resolveSeedIds(input)
+	if seedErr then
+		return nil, "sfxSimilar " .. seedErr
+	end
+	local assetId = if seedIds then nil else resolveAssetId(input)
+	if not seedIds and not assetId then
+		return nil, "sfxSimilar requires an asset_id string, a track table, a Sound, or an AudioPlayer, or a list of them"
 	end
 	local opts: any = extras or (type(input) == "table" and input or {})
 	return invoke(getRemotes(self), "SfxSimilar", {
 		asset_id = assetId,
+		asset_ids = seedIds,
 		limit = opts.limit,
 		offset = opts.offset,
 		filters = opts.filters,
diff --git a/src/init.luau b/src/init.luau
index fa6dec1..e8c679b 100644
--- a/src/init.luau
+++ b/src/init.luau
@@ -77,7 +77,10 @@ export type LookupOptions = {
 }
 
 export type SimilarOptions = {
-	asset_id: string,
+	asset_id: string?,
+	-- Seed list (up to 100): results sound like the set as a whole. Use
+	-- instead of asset_id.
+	asset_ids: { AssetIdResolvable }?,
 	limit: number?,
 	offset: number?,
 	playerId: number?,
@@ -88,6 +91,8 @@ export type SimilarOptions = {
 			max: number?,
 		}?,
 	}?,
+	max_score: number?,
+	dedupe: boolean?,
 }
 
 export type SfxSearchOptions = {
@@ -111,7 +116,10 @@ export type SfxSearchOptions = {
 }
 
 export type SfxSimilarOptions = {
-	asset_id: string,
+	asset_id: string?,
+	-- Seed list (up to 100): results sound like the set as a whole. Use
+	-- instead of asset_id.
+	asset_ids: { AssetIdResolvable }?,
 	limit: number?,
 	offset: number?,
 	playerId: number?,
@@ -123,6 +131,8 @@ export type SfxSimilarOptions = {
 			max: number?,
 		}?,
 	}?,
+	max_score: number?,
+	dedupe: boolean?,
 }
 
 -- Anything you can extract an asset_id from. The table arm uses an open
@@ -131,6 +141,14 @@ export type SfxSimilarOptions = {
 -- strict mode without a sealed-table mismatch.
 export type AssetIdResolvable = string | { asset_id: string, [string]: any } | Sound | AudioPlayer
 
+-- Seed-list forms of similar / sfxSimilar: an array of anything
+-- AssetIdResolvable (`{ track1, track2 }`, a playlist's tracks), or the
+-- options table carrying `asset_ids`. The API blends the seeds into one
+-- acoustic profile.
+export type SeedList = { AssetIdResolvable }
+export type SimilarInput = AssetIdResolvable | SeedList | SimilarOptions
+export type SfxSimilarInput = AssetIdResolvable | SeedList | SfxSimilarOptions
+
 -- "Extras" mirror the legacy *Options shapes minus asset_id. Used as the
 -- optional second positional arg in the polymorphic forms — when you pass a
 -- Track / Sound / string and still want limit/offset/filters/playerId.
@@ -260,6 +278,10 @@ export type SimilarResult = {
 		total: number,
 		limit: number,
 		offset: number,
+		-- asset_ids requests only: seeds that resolved, and the ids skipped
+		-- (unknown, not yet analyzed, or not public).
+		seeds_used: number?,
+		seeds_ignored: { string }?,
 	},
 }
 
@@ -297,6 +319,10 @@ export type SfxSimilarResult = {
 		total: number,
 		limit: number,
 		offset: number,
+		-- asset_ids requests only: seeds that resolved, and the ids skipped
+		-- (unknown, not yet analyzed, or not public).
+		seeds_used: number?,
+		seeds_ignored: { string }?,
 	},
 }
 
@@ -670,6 +696,39 @@ local function resolveAssetId(input: any): string?
 	return nil
 end
 
+-- Seed-list arm of similar / sfxSimilar: an array of AssetIdResolvable
+-- (`{ "123", track, sound }`) or an options table carrying `asset_ids`.
+-- Returns (nil, nil) when `input` is not a seed list at all, so the caller
+-- falls through to the single-seed arms; (nil, reason) when it is one but an
+-- element doesn't resolve; (ids, nil) otherwise. Checked before
+-- resolveAssetId, which returns nil for any table without `asset_id`.
+-- Mirrored in src/AudioScapeClient.luau, same trade-off as resolveAssetId.
+local function resolveSeedIds(input: any): ({ string }?, string?)
+	if type(input) ~= "table" or input.asset_id ~= nil then
+		return nil, nil
+	end
+	local list: any
+	if type(input.asset_ids) == "table" then
+		list = input.asset_ids
+	elseif #input > 0 then
+		list = input
+	else
+		return nil, nil
+	end
+	local ids: { string } = {}
+	for i, item in ipairs(list) do
+		local id = resolveAssetId(item)
+		if not id then
+			return nil, string.format("asset_ids[%d] is not an asset_id string, a track table, a Sound, or an AudioPlayer", i)
+		end
+		table.insert(ids, id)
+	end
+	if #ids == 0 then
+		return nil, "asset_ids must be a non-empty list"
+	end
+	return ids, nil
+end
+
 local function request(
 	self: AudioScapeInstance,
 	path: string,
@@ -1189,25 +1248,34 @@ function AudioScape.lookup(self: AudioScapeInstance, options: LookupOptions): (S
 end
 
 -- Polymorphic input: pass an asset_id string, a Track-shaped table, a Sound,
--- or an AudioPlayer. `extras` carries limit/offset/filters/playerId; if you
--- pass the legacy options table (`{ asset_id, limit, ... }`) those fields are
--- read from the input itself when `extras` is omitted.
+-- or an AudioPlayer — or a list of those (`playlist.tracks`) to get tracks
+-- that sound like the whole set. `extras` carries limit/offset/filters/
+-- playerId; if you pass the legacy options table (`{ asset_id, limit, ... }`
+-- or `{ asset_ids, limit, ... }`) those fields are read from the input itself
+-- when `extras` is omitted.
 function AudioScape.similar(
 	self: AudioScapeInstance,
-	input: AssetIdResolvable,
+	input: SimilarInput,
 	extras: SimilarExtras?
 ): (SimilarResult?, string?)
-	local assetId = resolveAssetId(input)
-	if not assetId then
-		return nil, "similar requires an asset_id string, a track table, a Sound, or an AudioPlayer"
+	local seedIds, seedErr = resolveSeedIds(input)
+	if seedErr then
+		return nil, "similar " .. seedErr
+	end
+	local assetId = if seedIds then nil else resolveAssetId(input)
+	if not seedIds and not assetId then
+		return nil, "similar requires an asset_id string, a track table, a Sound, or an AudioPlayer, or a list of them"
 	end
 
 	local opts: any = extras or (type(input) == "table" and input or {})
 
 	-- GET so CloudFront edge-caches. dedupe=false is omitted (no point
-	-- sending the no-op default — keeps the cache key clean).
+	-- sending the no-op default — keeps the cache key clean). A seed list
+	-- ships as one comma-separated param: the API takes a CSV, and buildQuery
+	-- would JSON-encode a table.
 	return requestGet(self, "/v1/similar", {
 		asset_id = assetId,
+		asset_ids = if seedIds then table.concat(seedIds, ",") else nil,
 		limit = opts.limit,
 		offset = opts.offset,
 		filters = opts.filters,
@@ -1249,20 +1317,26 @@ end
 -- input — see similar() for the (input, extras?) contract.
 function AudioScape.sfxSimilar(
 	self: AudioScapeInstance,
-	input: AssetIdResolvable,
+	input: SfxSimilarInput,
 	extras: SfxSimilarExtras?
 ): (SfxSimilarResult?, string?)
-	local assetId = resolveAssetId(input)
-	if not assetId then
-		return nil, "sfxSimilar requires an asset_id string, a track table, a Sound, or an AudioPlayer"
+	local seedIds, seedErr = resolveSeedIds(input)
+	if seedErr then
+		return nil, "sfxSimilar " .. seedErr
+	end
+	local assetId = if seedIds then nil else resolveAssetId(input)
+	if not seedIds and not assetId then
+		return nil, "sfxSimilar requires an asset_id string, a track table, a Sound, or an AudioPlayer, or a list of them"
 	end
 
 	local opts: any = extras or (type(input) == "table" and input or {})
 
 	-- GET so CloudFront edge-caches. dedupe=false is omitted (no point
-	-- sending the no-op default — keeps the cache key clean).
+	-- sending the no-op default — keeps the cache key clean). Seed list as a
+	-- CSV, same as similar.
 	return requestGet(self, "/v1/sfx/similar", {
 		asset_id = assetId,
+		asset_ids = if seedIds then table.concat(seedIds, ",") else nil,
 		limit = opts.limit,
 		offset = opts.offset,
 		filters = opts.filters,
@@ -2308,14 +2382,17 @@ function AudioScape.enableClientAccess(self: AudioScapeInstance)
 		if not checkRateLimit(player) then
 			return nil, "Rate limited — please wait before making another request"
 		end
-		if type(options) ~= "table" or type(options.asset_id) ~= "string" then
-			return nil, "similar requires a table with an asset_id string"
+		if type(options) ~= "table" or (type(options.asset_id) ~= "string" and type(options.asset_ids) ~= "table") then
+			return nil, "similar requires a table with an asset_id string or an asset_ids list"
 		end
 		return self:similar({
 			asset_id = options.asset_id,
+			asset_ids = options.asset_ids,
 			limit = options.limit,
 			offset = options.offset,
 			filters = options.filters,
+			max_score = options.max_score,
+			dedupe = options.dedupe,
 			playerId = player.UserId,
 		})
 	end)
@@ -2355,14 +2432,17 @@ function AudioScape.enableClientAccess(self: AudioScapeInstance)
 		if not checkRateLimit(player) then
 			return nil, "Rate limited — please wait before making another request"
 		end
-		if type(options) ~= "table" or type(options.asset_id) ~= "string" then
-			return nil, "sfxSimilar requires a table with an asset_id string"
+		if type(options) ~= "table" or (type(options.asset_id) ~= "string" and type(options.asset_ids) ~= "table") then
+			return nil, "sfxSimilar requires a table with an asset_id string or an asset_ids list"
 		end
 		return self:sfxSimilar({
 			asset_id = options.asset_id,
+			asset_ids = options.asset_ids,
 			limit = options.limit,
 			offset = options.offset,
 			filters = options.filters,
+			max_score = options.max_score,
+			dedupe = options.dedupe,
 			playerId = player.UserId,
 		})
 	end)
diff --git a/tests/sfxSimilar.spec.luau b/tests/sfxSimilar.spec.luau
index c4597c1..34f7c45 100644
--- a/tests/sfxSimilar.spec.luau
+++ b/tests/sfxSimilar.spec.luau
@@ -186,3 +186,42 @@ do
 	local q = decodeQuery(http.requests[1].url)
 	assert(q.max_score == "0.95", "extras.max_score wins; got: " .. tostring(q.max_score))
 end
+
+-- 11. Seed list: array input → asset_ids CSV on the wire, no asset_id
+do
+	local http = mockHttp.new()
+	local sdk = loadSdk({ http = http })
+	local client = (sdk :: any).new("test-key")
+
+	http:queueResponse(emptyResponse())
+	-- Mixed list (string + SfxTrack-shaped table): annotate so strict mode
+	-- doesn't infer `{ string }` from the first element.
+	local seeds: { any } = { "9083837523", { asset_id = "18672006515" } }
+	local result, err = client:sfxSimilar(seeds, { limit = 10 })
+	assert(result and not err, "seed list should succeed; err: " .. tostring(err))
+
+	local q = decodeQuery(http.requests[1].url)
+	assert(
+		q.asset_ids == "9083837523,18672006515",
+		"seed list → asset_ids CSV on the wire; got: " .. tostring(q.asset_ids)
+	)
+	assert(q.asset_id == nil, "seed list sends no asset_id; got: " .. tostring(q.asset_id))
+	assert(q.limit == "10", "extras.limit carried with a seed list; got: " .. tostring(q.limit))
+end
+
+-- 12. Seed list: legacy options-table form; bad element rejected pre-flight
+do
+	local http = mockHttp.new()
+	local sdk = loadSdk({ http = http })
+	local client = (sdk :: any).new("test-key")
+
+	http:queueResponse(emptyResponse())
+	client:sfxSimilar({ asset_ids = { "1", "2" }, limit = 3, filters = { categories = { "foley" } } })
+	local q = decodeQuery(http.requests[1].url)
+	assert(q.asset_ids == "1,2", "options-table asset_ids → CSV; got: " .. tostring(q.asset_ids))
+	assert(q.filters and q.filters:find("foley", 1, true), "options-table filters carried; got: " .. tostring(q.filters))
+
+	local r, e = client:sfxSimilar({ "1", "" })
+	assert(r == nil and e and e:find("asset_ids[2]", 1, true), "empty-string element named by index; got: " .. tostring(e))
+	assert(#http.requests == 1, "no HTTP for an invalid seed list")
+end
diff --git a/tests/similar.spec.luau b/tests/similar.spec.luau
index bb12470..0689459 100644
--- a/tests/similar.spec.luau
+++ b/tests/similar.spec.luau
@@ -227,3 +227,81 @@ do
 	assert(q.max_score == "0.95", "extras.max_score wins; got: " .. tostring(q.max_score))
 	assert(q.dedupe == "true", "extras.dedupe carried alongside max_score; got: " .. tostring(q.dedupe))
 end
+
+-- 13. Seed list: array of strings → asset_ids CSV on the wire, no asset_id
+do
+	local http = mockHttp.new()
+	local sdk = loadSdk({ http = http })
+	local client = (sdk :: any).new("test-key")
+
+	http:queueResponse(emptyResponse())
+	local result, err = client:similar({ "1234", "rbxassetid://5678" }, { limit = 20 })
+	assert(result and not err, "seed list should succeed; err: " .. tostring(err))
+	assert(#http.requests == 1, "exactly one HTTP call for a seed list")
+
+	local q = decodeQuery(http.requests[1].url)
+	assert(q.asset_ids == "1234,5678", "seed list → asset_ids=1234,5678 on the wire; got: " .. tostring(q.asset_ids))
+	assert(q.asset_id == nil, "seed list sends no asset_id; got: " .. tostring(q.asset_id))
+	assert(q.limit == "20", "extras.limit carried with a seed list; got: " .. tostring(q.limit))
+end
+
+-- 14. Seed list: array of Track tables (a playlist's tracks)
+do
+	local http = mockHttp.new()
+	local sdk = loadSdk({ http = http })
+	local client = (sdk :: any).new("test-key")
+
+	http:queueResponse(emptyResponse())
+	client:similar({ { asset_id = "11", name = "A" }, { asset_id = "22", name = "B" } })
+
+	local q = decodeQuery(http.requests[1].url)
+	assert(q.asset_ids == "11,22", "Track tables → asset_ids=11,22; got: " .. tostring(q.asset_ids))
+end
+
+-- 15. Seed list: legacy options-table form carries limit/filters/playerId
+do
+	local http = mockHttp.new()
+	local sdk = loadSdk({ http = http })
+	local client = (sdk :: any).new("test-key")
+
+	http:queueResponse(emptyResponse())
+	client:similar({ asset_ids = { "33", "44" }, limit = 5, playerId = 42, filters = { genres = { "rock" } } })
+
+	local recorded = http.requests[1]
+	local q = decodeQuery(recorded.url)
+	assert(q.asset_ids == "33,44", "options-table asset_ids → CSV; got: " .. tostring(q.asset_ids))
+	assert(q.asset_id == nil, "options-table seed list sends no asset_id; got: " .. tostring(q.asset_id))
+	assert(q.limit == "5", "options-table limit carried; got: " .. tostring(q.limit))
+	assert(q.filters and q.filters:find("rock", 1, true), "options-table filters carried; got: " .. tostring(q.filters))
+	assert(
+		recorded.headers and recorded.headers["X-Player-Id"] == "42",
+		"options-table playerId → X-Player-Id; got: " .. tostring(recorded.headers and recorded.headers["X-Player-Id"])
+	)
+end
+
+-- 16. Validation: an element that doesn't resolve → pre-flight error naming it, no HTTP
+do
+	local http = mockHttp.new()
+	local sdk = loadSdk({ http = http })
+	local client = (sdk :: any).new("test-key")
+
+	-- Mixed list: strict mode infers the array type from the first element,
+	-- so annotate to test the runtime check rather than the type checker.
+	local seeds: { any } = { "1234", { name = "no id" } }
+	local r, e = client:similar(seeds)
+	assert(r == nil, "bad element → nil result")
+	assert(e and e:find("asset_ids[2]", 1, true), "error names the offending index; got: " .. tostring(e))
+	assert(#http.requests == 0, "no HTTP for an invalid seed list")
+end
+
+-- 17. Validation: empty asset_ids
+do
+	local http = mockHttp.new()
+	local sdk = loadSdk({ http = http })
+	local client = (sdk :: any).new("test-key")
+
+	local r, e = client:similar({ asset_ids = {} })
+	assert(r == nil, "empty list → nil result")
+	assert(e and e:find("non-empty", 1, true), "empty list rejected pre-flight; got: " .. tostring(e))
+	assert(#http.requests == 0, "no HTTP for an empty seed list")
+end
diff --git a/wally.toml b/wally.toml
index 01fdfa5..01c3c77 100644
--- a/wally.toml
+++ b/wally.toml
@@ -1,6 +1,6 @@
 [package]
 name = "this-fifo/audioscape-sdk"
-version = "0.21.0"
+version = "0.22.0"
 registry = "https://github.com/UpliftGames/wally-index"
 realm = "server"
 license = "MIT"