diff --git a/AGENTS.md b/AGENTS.md
index 1ff8196..5713b68 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -14,6 +14,45 @@ This file defines agent workflow and points to project specifications. Implement
 4. When adding a new subsystem or feature, add/update the relevant spec in `specs/`.
 5. Keep AGENTS.md high-level; do not duplicate implementation details from specs.
 
+## Updating NASA Data Files
+
+Use the Justfile workflow; do not reconstruct the TAP URLs or deployment steps
+from memory.
+
+```bash
+# 1. Download both NASA VOTables.
+just download-data
+
+# 2. Convert both VOTables to Parquet and generate both metadata TOML files.
+just convert-raw-files
+
+# 3. Confirm all generated runtime files exist and are non-empty.
+just verify-data
+
+# 4. Upload Parquet and metadata TOML files through Ansible.
+just ansible-upload-data
+
+# 5. Restart the deployed application so it loads the new files.
+just ansible-deploy
+```
+
+If the VOTable files have already been downloaded, start with
+`just convert-raw-files`. Ansible commands require
+`infrastructure/ansible/.env` with `DROPLET_IP` configured.
+
+The expected source files are `data/stellarhosts.vot` and
+`data/exoplanets.vot`. Conversion generates and overwrites:
+
+- `data/stellarhosts.parquet`
+- `data/exoplanets.parquet`
+- `data/stellarhosts-metadata.toml`
+- `data/exoplanets-metadata.toml`
+
+`convert-raw-files` processes every `.vot` file in `data/`; remove temporary or
+old VOTables before running it. Upload only the generated Parquet/TOML files,
+then restart/deploy because the application loads them at startup. See
+`specs/data-management.md` and `DEPLOY.md` for technical details.
+
 ## Agent Rules
 1. **Explicit Instruction Compliance:** Do not perform actions (file edits or command execution) without explicit user request.
 2. **Confidence Threshold:** If below ~70% confidence about a request or outcome, stop and ask for clarification.
diff --git a/Cargo.lock b/Cargo.lock
index fd4222b..0a84161 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -532,16 +532,6 @@ dependencies = [
  "serde",
 ]
 
-[[package]]
-name = "calendrical_calculations"
-version = "0.2.4"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5abbd6eeda6885048d357edc66748eea6e0268e3dd11f326fff5bd248d779c26"
-dependencies = [
- "core_maths",
- "displaydoc",
-]
-
 [[package]]
 name = "camino"
 version = "1.2.2"
@@ -841,15 +831,6 @@ version = "0.8.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "773648b94d0e5d620f64f280777445740e61fe701025087ec8b57f45c791888b"
 
-[[package]]
-name = "core_maths"
-version = "0.1.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "77745e017f5edba1a9c1d854f6f3a52dac8a12dd5af5d2f54aecf61e43d80d30"
-dependencies = [
- "libm",
-]
-
 [[package]]
 name = "cpufeatures"
 version = "0.2.17"
@@ -1294,7 +1275,7 @@ version = "0.1.0"
 
 [[package]]
 name = "exoplanets-catalog"
-version = "0.3.9"
+version = "0.3.10"
 dependencies = [
  "axum",
  "console_error_panic_hook",
@@ -1879,50 +1860,6 @@ dependencies = [
  "cc",
 ]
 
-[[package]]
-name = "icu_calendar"
-version = "2.2.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a2b2acc6263f494f1df50685b53ff8e57869e47d5c6fe39c23d518ae9a4f3e45"
-dependencies = [
- "calendrical_calculations",
- "displaydoc",
- "icu_calendar_data",
- "icu_locale",
- "icu_locale_core",
- "icu_provider",
- "tinystr",
- "zerovec",
-]
-
-[[package]]
-name = "icu_calendar_data"
-version = "2.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "118577bcf3a0fa7c6ac0a7d6e951814da84ee56b9b1f68fb4d8d10b08cefaf4d"
-
-[[package]]
-name = "icu_casemap"
-version = "2.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "070f98b5b82798fcb93654bf96ed9f40064fc44c86f51a09ea711092cd5cc5be"
-dependencies = [
- "icu_casemap_data",
- "icu_collections",
- "icu_locale_core",
- "icu_properties",
- "icu_provider",
- "potential_utf",
- "writeable",
- "zerovec",
-]
-
-[[package]]
-name = "icu_casemap_data"
-version = "2.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "846b0857ca091204be3c874bc93daaf89d4777e8d2d20b0d3ffe8f671d98014b"
-
 [[package]]
 name = "icu_collections"
 version = "2.2.0"
@@ -1931,125 +1868,12 @@ checksum = "2984d1cd16c883d7935b9e07e44071dca8d917fd52ecc02c04d5fa0b5a3f191c"
 dependencies = [
  "displaydoc",
  "potential_utf",
- "serde",
  "utf8_iter",
  "yoke",
  "zerofrom",
  "zerovec",
 ]
 
-[[package]]
-name = "icu_datetime"
-version = "2.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "989d56ea5bbc43ae2b4e0388874b002884eaf4ed3a76c84a6c8c5ad575e04d72"
-dependencies = [
- "displaydoc",
- "fixed_decimal",
- "icu_calendar",
- "icu_datetime_data",
- "icu_decimal",
- "icu_locale",
- "icu_locale_core",
- "icu_pattern",
- "icu_plurals",
- "icu_provider",
- "icu_time",
- "potential_utf",
- "tinystr",
- "writeable",
- "zerovec",
-]
-
-[[package]]
-name = "icu_datetime_data"
-version = "2.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "40d3cc1b690d9703202bc319692ac8a1f3a6390686f0930ff40542450fa34f0b"
-
-[[package]]
-name = "icu_decimal"
-version = "2.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "288247df2e32aa776ac54fdd64de552149ac43cb840f2761811f0e8d09719dd4"
-dependencies = [
- "displaydoc",
- "fixed_decimal",
- "icu_decimal_data",
- "icu_locale",
- "icu_locale_core",
- "icu_pattern",
- "icu_plurals",
- "icu_provider",
- "writeable",
- "zerovec",
-]
-
-[[package]]
-name = "icu_decimal_data"
-version = "2.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6f14a5ca9e8af29eef62064f269078424283d90dbaffeac5225addf62aaabc22"
-
-[[package]]
-name = "icu_experimental"
-version = "0.5.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0a881116e620fd635f564fd9cb9bc36c256b9da2221df8b3f55643d8ef32140f"
-dependencies = [
- "displaydoc",
- "either",
- "fixed_decimal",
- "icu_casemap",
- "icu_collections",
- "icu_decimal",
- "icu_experimental_data",
- "icu_list",
- "icu_locale",
- "icu_locale_core",
- "icu_normalizer",
- "icu_pattern",
- "icu_plurals",
- "icu_properties",
- "icu_provider",
- "litemap",
- "num-bigint",
- "num-rational",
- "num-traits",
- "potential_utf",
- "smallvec",
- "tinystr",
- "writeable",
- "zerotrie",
- "zerovec",
-]
-
-[[package]]
-name = "icu_experimental_data"
-version = "0.5.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f72090d4f08a2bc94565cb02de6d5b87939424e462d9927d73a34f6f8e5d1232"
-
-[[package]]
-name = "icu_list"
-version = "2.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "aeeaf517689324395bed4767f7c65504f5455942ed4c14ee54c2087ca00b816e"
-dependencies = [
- "icu_list_data",
- "icu_locale",
- "icu_provider",
- "regex-automata",
- "writeable",
- "zerovec",
-]
-
-[[package]]
-name = "icu_list_data"
-version = "2.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ed62dbf114db9a4163481ed071509c4cd52cbcef9cb85979eba08a95549d73f3"
-
 [[package]]
 name = "icu_locale"
 version = "2.2.0"
@@ -2105,20 +1929,6 @@ version = "2.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "da3be0ae77ea334f4da67c12f149704f19f81d1adf7c51cf482943e84a2bad38"
 
-[[package]]
-name = "icu_pattern"
-version = "0.4.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1c4c568054ffe735398a9f4c55aec37ad7c768844553cc0978f09cc9b933a1fb"
-dependencies = [
- "displaydoc",
- "either",
- "serde",
- "writeable",
- "yoke",
- "zerovec",
-]
-
 [[package]]
 name = "icu_plurals"
 version = "2.2.0"
@@ -2148,7 +1958,6 @@ dependencies = [
  "icu_locale_core",
  "icu_properties_data",
  "icu_provider",
- "serde",
  "zerotrie",
  "zerovec",
 ]
@@ -2176,29 +1985,6 @@ dependencies = [
  "zerovec",
 ]
 
-[[package]]
-name = "icu_time"
-version = "2.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ec3af0c141da0a61d4f6970cd1d5f4b388b17ea22f8124f8f6049d3d5147586a"
-dependencies = [
- "calendrical_calculations",
- "displaydoc",
- "icu_calendar",
- "icu_locale_core",
- "icu_provider",
- "icu_time_data",
- "serde",
- "zerotrie",
- "zerovec",
-]
-
-[[package]]
-name = "icu_time_data"
-version = "2.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6f2f8aeca682d874a5247084aa4fb7d1cef9ba45d889c21209a8818dcaaa0ec9"
-
 [[package]]
 name = "id-arena"
 version = "2.3.0"
@@ -2410,9 +2196,11 @@ dependencies = [
  "codee",
  "cookie",
  "default-struct-builder",
+ "http",
  "js-sys",
  "lazy_static",
  "leptos",
+ "leptos_axum",
  "paste",
  "send_wrapper",
  "thiserror 2.0.18",
@@ -2498,18 +2286,14 @@ checksum = "efc04f323545e008d9b6fe696d733557846ee17024af65b86b16c44a5c724d7b"
 dependencies = [
  "codee",
  "default-struct-builder",
- "icu_calendar",
- "icu_datetime",
- "icu_decimal",
- "icu_experimental",
- "icu_list",
  "icu_locale",
- "icu_plurals",
+ "js-sys",
  "leptos",
  "leptos-use",
  "leptos_i18n_macro",
  "leptos_meta",
  "serde",
+ "serde-wasm-bindgen",
  "typed-builder",
  "wasm-bindgen",
  "writeable",
@@ -2916,16 +2700,6 @@ dependencies = [
  "windows-sys 0.61.2",
 ]
 
-[[package]]
-name = "num-bigint"
-version = "0.4.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a5e44f723f1133c9deac646763579fdb3ac745e418f2a7af9cd0c431da1f20b9"
-dependencies = [
- "num-integer",
- "num-traits",
-]
-
 [[package]]
 name = "num-conv"
 version = "0.2.2"
@@ -2943,26 +2717,6 @@ dependencies = [
  "syn",
 ]
 
-[[package]]
-name = "num-integer"
-version = "0.1.46"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7969661fd2958a5cb096e56c8e1ad0444ac2bbcd0061bd28660485a44879858f"
-dependencies = [
- "num-traits",
-]
-
-[[package]]
-name = "num-rational"
-version = "0.4.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f83d14da390562dca69fc84082e73e548e1ad308d24accdedd2720017cb37824"
-dependencies = [
- "num-bigint",
- "num-integer",
- "num-traits",
-]
-
 [[package]]
 name = "num-traits"
 version = "0.2.19"
@@ -4615,6 +4369,17 @@ dependencies = [
  "serde_derive",
 ]
 
+[[package]]
+name = "serde-wasm-bindgen"
+version = "0.6.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8302e169f0eddcc139c70f139d19d6467353af16f9fce27e8c30158036a1e16b"
+dependencies = [
+ "js-sys",
+ "serde",
+ "wasm-bindgen",
+]
+
 [[package]]
 name = "serde_core"
 version = "1.0.228"
@@ -6409,9 +6174,6 @@ name = "writeable"
 version = "0.6.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1ffae5123b2d3fc086436f8834ae3ab053a283cfac8fe0a0b8eaae044768a4c4"
-dependencies = [
- "either",
-]
 
 [[package]]
 name = "wyz"
diff --git a/Cargo.toml b/Cargo.toml
index 55a5185..2cd0ebe 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "exoplanets-catalog"
-version = "0.3.9"
+version = "0.3.10"
 edition = "2024"
 
 [workspace]
@@ -49,7 +49,11 @@ utoipa-swagger-ui = { version = "9.0", features = ["axum"], optional = true }
 sqlparser = { version = "0.60", optional = true }
 moka = { version = "0.12", features = ["future"] }
 rmcp = { version = "1.6.0", features = ["server", "macros", "transport-streamable-http-server", "schemars"], optional = true }
-leptos_i18n = "0.6.2"
+leptos_i18n = { version = "0.6.2", default-features = false }
+
+[package.metadata.leptos-i18n]
+default = "en"
+locales = ["en", "zh-CN", "ja"]
 
 # [build-dependencies]
 # markdown = "1.0.0-alpha"
@@ -60,7 +64,7 @@ serde_json = { workspace = true }
 rand = "0.9"
 
 [features]
-hydrate = ["leptos/hydrate", "dep:web-sys"]
+hydrate = ["leptos/hydrate", "leptos_i18n/hydrate", "dep:web-sys"]
 ssr = [
     "dep:axum",
     "dep:tokio",
@@ -70,6 +74,7 @@ ssr = [
     "leptos/ssr",
     "leptos_meta/ssr",
     "leptos_router/ssr",
+    "leptos_i18n/axum",
     "dep:tracing",
     "dep:tracing-subscriber",
     # data processing
diff --git a/Justfile b/Justfile
index 5e79aff..c18fbd1 100644
--- a/Justfile
+++ b/Justfile
@@ -2,18 +2,22 @@
 clippy:
   cargo clippy --all-targets --all-features -- -D warnings
 
-# Data download commands
-download-stellarhosts:
-  curl "https://exoplanetarchive.ipac.caltech.edu/TAP/sync?query=select+*+from+stellarhosts" -L --max-time 3000 > data/stellarhosts.vot
-
-download-exoplanets:
-  curl "https://exoplanetarchive.ipac.caltech.edu/TAP/sync?query=select+*+from+ps" -L --max-time 3000 > data/exoplanets.vot
+# Download both NASA VOTable sources.
+download-data:
+  mkdir -p data
+  curl --fail --location --remove-on-error --max-time 3000 --output data/stellarhosts.vot "https://exoplanetarchive.ipac.caltech.edu/TAP/sync?query=select+*+from+stellarhosts&format=votable"
+  curl --fail --location --remove-on-error --max-time 3000 --output data/exoplanets.vot "https://exoplanetarchive.ipac.caltech.edu/TAP/sync?query=select+*+from+pscomppars&format=votable"
 
+# Convert VOTables to Parquet and generate matching metadata TOML files.
 convert-raw-files:
   cargo run -p exodata -- dev convert-raw-files --data-dir data
 
-stellarhosts-metadata:
-  cargo run -p exodata -- dev view-metadata --path data/stellarhosts.vot
+# Confirm all runtime files exist and are non-empty.
+verify-data:
+  test -s data/stellarhosts.parquet
+  test -s data/exoplanets.parquet
+  test -s data/stellarhosts-metadata.toml
+  test -s data/exoplanets-metadata.toml
 
 # =============================================================================
 # Ansible Deployment Commands
@@ -44,7 +48,7 @@ ansible-deploy:
 ansible-ssl:
   cd {{ansible_dir}} && ansible-playbook {{ansible_args}} playbooks/ssl.yml
 
-# Upload parquet data files
+# Upload Parquet data and metadata TOML files
 ansible-upload-data:
   cd {{ansible_dir}} && ansible-playbook {{ansible_args}} playbooks/upload-data.yml
 
diff --git a/docs/i18n/ja/index.md b/docs/i18n/ja/index.md
new file mode 100644
index 0000000..a36c07e
--- /dev/null
+++ b/docs/i18n/ja/index.md
@@ -0,0 +1,9 @@
+# [精密な系外惑星データを使って推論する](#mcp-exoplanet-data)
+
+Exodata は、ホスト型 MCP サーバーを通じて、NASA Exoplanet Archive の精密なデータへの構造化アクセスを AI エージェントに提供します。
+
+エージェントは一般的なモデル知識に頼ったり大規模なテーブルを手作業で調べたりせず、カタログのスキーマを確認し、SQL クエリを組み立て、返されたレコードを基に推論できます。
+
+利用可能なテーブルと列を実行時に確認するため、回答をカタログの結果に基づかせることができます。正確な値が重要な比較、絞り込み、ランキング、追加質問に適しています。
+
+互換性のある MCP クライアントを接続すると、カタログの現在の構造化データに基づく質問ができます。
diff --git a/docs/i18n/zh-CN/index.md b/docs/i18n/zh-CN/index.md
new file mode 100644
index 0000000..4ce6f59
--- /dev/null
+++ b/docs/i18n/zh-CN/index.md
@@ -0,0 +1,9 @@
+# [基于精确的系外行星数据进行推理](#mcp-exoplanet-data)
+
+Exodata 通过托管的 MCP 服务器，为 AI 智能体提供对 NASA 系外行星档案精确数据的结构化访问。
+
+智能体可以检查目录模式、编写 SQL 查询并根据返回的记录进行推理，而不是依赖模型的一般知识或手动浏览大型数据表。
+
+由于智能体会在运行时发现可用的数据表和字段，其回答能够以目录查询结果为依据。这适合需要精确数值的比较、筛选、排名和后续问题。
+
+连接兼容的 MCP 客户端，即可提出由目录当前结构化数据支持的问题。
diff --git a/docs/index.md b/docs/index.md
index 550829b..b97cfe1 100644
--- a/docs/index.md
+++ b/docs/index.md
@@ -1,13 +1,15 @@
-# Use the catalog, not just the table
+# [Reason over precise exoplanet data](#mcp-exoplanet-data)
 
-Exodata represents NASA Exoplanet Archive tables as a practical set of access
-paths for people, scripts, and AI-enabled tools.
+Exodata gives AI agents structured access to precise NASA Exoplanet Archive
+data through a hosted MCP server.
 
-Large scientific tables are powerful, but they are hard to scan by hand. This
-site keeps the table view available while adding shareable routes, focused
-JSON/CSV exports, REST and SQL endpoints, a local CLI, and an MCP server for
-natural-language-assisted catalog queries.
+Agents can inspect the catalog schema, compose SQL queries, and reason over the
+returned records instead of relying on general model knowledge or manually
+scanning large tables.
 
-Start with the website when you want to browse. Use exports when you need a
-single object record. Use the API, SQL endpoint, CLI, or MCP server when you
-want the dataset inside code, notebooks, local tools, or an agent workflow.
+Because the agent discovers the available tables and columns at runtime, its
+answers can stay grounded in catalog results. This is useful for comparisons,
+filtered searches, rankings, and follow-up questions where exact values matter.
+
+Connect a compatible MCP client to ask questions backed by the catalog's
+current structured data.
diff --git a/locales/en.json b/locales/en.json
new file mode 100644
index 0000000..38c769a
--- /dev/null
+++ b/locales/en.json
@@ -0,0 +1,99 @@
+{
+  "nav": {
+    "overview": "Overview",
+    "stellar_hosts": "Stellar Hosts",
+    "exoplanets": "Exoplanets",
+    "insights": "Insights",
+    "docs": "Docs",
+    "api": "API",
+    "github_repository": "GitHub repository",
+    "open_menu": "Open navigation menu",
+    "close_menu": "Close navigation menu",
+    "mobile_navigation": "Mobile navigation",
+    "language": "Language"
+  },
+  "home": {
+    "title": "Exoplanets Catalog",
+    "description": "Explore confirmed exoplanets and their host stars with searchable tables, discovery stats, and server-rendered detail pages.",
+    "hero_title": "🌌 Exoplanet Archive",
+    "hero_subtitle": "Exploring the cosmos: A comprehensive catalog of confirmed exoplanets and their host stars",
+    "loading": "Loading catalog data...",
+    "connection_error": "Connection Error",
+    "error_loading": "Error loading data",
+    "stellar_systems": "Stellar Systems",
+    "host_stars_catalogued": "Host stars catalogued",
+    "exoplanets": "Exoplanets",
+    "distinct_planets": "Distinct planets in the catalog",
+    "average_temperature": "Avg Stellar Temp",
+    "mean_temperature": "Mean effective temperature",
+    "average_distance": "Avg Distance",
+    "mean_distance": "Mean system distance",
+    "live": "LIVE",
+    "planet_classifications": "Planet Classifications",
+    "planet_classifications_subtitle": "Distinct planets grouped by canonical radius",
+    "orbital_periods": "Orbital Periods",
+    "orbital_periods_subtitle": "Distinct planets grouped by canonical period",
+    "discovery_methods": "Discovery Methods",
+    "discovery_methods_subtitle": "Distinct planets grouped by canonical method",
+    "discovery_years": "Discovery Years",
+    "discovery_years_subtitle": "Distinct planets grouped by earliest discovery year",
+    "temperature_bands": "Planet Temperature Bands",
+    "temperature_bands_subtitle": "Distinct planets grouped by canonical equilibrium temperature",
+    "detection_sources": "Detection Sources",
+    "detection_sources_subtitle": "Distinct planets grouped by discovery facility"
+  },
+  "manual": {
+    "examples_title": "Open a real catalog record",
+    "examples_subtitle": "Stable routes make pages, exports, API docs, and tool setup easy to share.",
+    "stellar_profile": "Stellar host profile",
+    "stellar_profile_description": "Open the TRAPPIST-1 host-system detail page.",
+    "planet_profile": "Planet profile",
+    "planet_profile_description": "Open the Kepler-22 b exoplanet detail page.",
+    "host_json": "Host JSON",
+    "host_json_description": "Download the full host detail payload.",
+    "host_csv": "Host CSV",
+    "host_csv_description": "Download matching host source rows.",
+    "planet_json": "Planet JSON",
+    "planet_json_description": "Download the full planet detail payload.",
+    "planet_csv": "Planet CSV",
+    "planet_csv_description": "Download matching planet source rows.",
+    "rest_api": "REST API",
+    "rest_api_description": "Query tables, schemas, details, insights, and SQL endpoints.",
+    "mcp_server": "MCP server",
+    "mcp_server_description": "Connect an AI client to inspect schema and query the catalog.",
+    "cli": "CLI",
+    "cli_description": "Query live or local data from the terminal.",
+    "swagger": "Swagger UI",
+    "swagger_description": "Explore the OpenAPI schema interactively.",
+    "connect_title": "Connect an MCP client",
+    "hosted_endpoint": "The hosted endpoint is",
+    "read": "Read the",
+    "mcp_introduction": "MCP introduction",
+    "or": "or the",
+    "mcp_docs": "Exodata MCP docs",
+    "copy": "Copy",
+    "copied": "Copied",
+    "ask": "Ask",
+    "tool": "Tool",
+    "sql": "SQL",
+    "result": "Result",
+    "ask_example": "nearest known planet-hosting systems with distance and planet count",
+    "result_example": "structured rows ready for a table, notebook, or follow-up query",
+    "cli_docs": "CLI docs",
+    "short_mcp_docs": "MCP docs",
+    "codex_config": "Codex config fallback",
+    "opencode_config": "OpenCode config",
+    "inspector_note": "Open the Inspector UI, then connect to the hosted endpoint with Streamable HTTP transport.",
+    "interaction_label": "Example catalog tool interaction"
+  },
+  "language": {
+    "english": "English",
+    "chinese": "Simplified Chinese",
+    "japanese": "Japanese"
+  },
+  "footer": {
+    "version": "Version",
+    "updated": "Updated",
+    "developed_by": "Developed by imscraping.ninja"
+  }
+}
diff --git a/locales/ja.json b/locales/ja.json
new file mode 100644
index 0000000..6a9df47
--- /dev/null
+++ b/locales/ja.json
@@ -0,0 +1,99 @@
+{
+  "nav": {
+    "overview": "概要",
+    "stellar_hosts": "恒星ホスト",
+    "exoplanets": "系外惑星",
+    "insights": "データ分析",
+    "docs": "ドキュメント",
+    "api": "API",
+    "github_repository": "GitHub リポジトリ",
+    "open_menu": "ナビゲーションメニューを開く",
+    "close_menu": "ナビゲーションメニューを閉じる",
+    "mobile_navigation": "モバイルナビゲーション",
+    "language": "言語"
+  },
+  "home": {
+    "title": "系外惑星カタログ",
+    "description": "検索可能なテーブル、発見統計、サーバー描画の詳細ページから、確認済み系外惑星とその主星を探索できます。",
+    "hero_title": "🌌 系外惑星アーカイブ",
+    "hero_subtitle": "宇宙を探索する：確認済み系外惑星とその主星の精密なカタログ",
+    "loading": "カタログデータを読み込んでいます…",
+    "connection_error": "接続エラー",
+    "error_loading": "データの読み込みエラー",
+    "stellar_systems": "恒星系",
+    "host_stars_catalogued": "収録済みの主星",
+    "exoplanets": "系外惑星",
+    "distinct_planets": "カタログ内の個別の惑星",
+    "average_temperature": "恒星の平均温度",
+    "mean_temperature": "平均有効温度",
+    "average_distance": "平均距離",
+    "mean_distance": "恒星系の平均距離",
+    "live": "ライブ",
+    "planet_classifications": "惑星の分類",
+    "planet_classifications_subtitle": "標準半径で分類した個別の惑星",
+    "orbital_periods": "公転周期",
+    "orbital_periods_subtitle": "標準周期で分類した個別の惑星",
+    "discovery_methods": "発見方法",
+    "discovery_methods_subtitle": "標準的な発見方法で分類した個別の惑星",
+    "discovery_years": "発見年",
+    "discovery_years_subtitle": "最初の発見年で分類した個別の惑星",
+    "temperature_bands": "惑星の温度帯",
+    "temperature_bands_subtitle": "標準平衡温度で分類した個別の惑星",
+    "detection_sources": "検出元",
+    "detection_sources_subtitle": "発見施設で分類した個別の惑星"
+  },
+  "manual": {
+    "examples_title": "実際のカタログレコードを開く",
+    "examples_subtitle": "安定したルートにより、ページ、エクスポート、API 文書、ツール設定を簡単に共有できます。",
+    "stellar_profile": "恒星ホストのプロフィール",
+    "stellar_profile_description": "TRAPPIST-1 ホスト系の詳細ページを開きます。",
+    "planet_profile": "惑星のプロフィール",
+    "planet_profile_description": "Kepler-22 b 系外惑星の詳細ページを開きます。",
+    "host_json": "ホスト JSON",
+    "host_json_description": "ホスト詳細の完全なデータをダウンロードします。",
+    "host_csv": "ホスト CSV",
+    "host_csv_description": "一致するホストのソース行をダウンロードします。",
+    "planet_json": "惑星 JSON",
+    "planet_json_description": "惑星詳細の完全なデータをダウンロードします。",
+    "planet_csv": "惑星 CSV",
+    "planet_csv_description": "一致する惑星のソース行をダウンロードします。",
+    "rest_api": "REST API",
+    "rest_api_description": "テーブル、スキーマ、詳細、分析、SQL エンドポイントを照会します。",
+    "mcp_server": "MCP サーバー",
+    "mcp_server_description": "AI クライアントを接続してスキーマを確認し、カタログを照会します。",
+    "cli": "CLI",
+    "cli_description": "ターミナルからオンラインまたはローカルのデータを照会します。",
+    "swagger": "Swagger UI",
+    "swagger_description": "OpenAPI スキーマを対話的に確認します。",
+    "connect_title": "MCP クライアントを接続",
+    "hosted_endpoint": "ホスト済みエンドポイント：",
+    "read": "参照：",
+    "mcp_introduction": "MCP 入門",
+    "or": "または",
+    "mcp_docs": "Exodata MCP ドキュメント",
+    "copy": "コピー",
+    "copied": "コピー済み",
+    "ask": "質問",
+    "tool": "ツール",
+    "sql": "SQL",
+    "result": "結果",
+    "ask_example": "既知の惑星ホスト系を距離が近い順に、距離と惑星数を含めて表示",
+    "result_example": "表、ノートブック、追加クエリに使える構造化された行",
+    "cli_docs": "CLI ドキュメント",
+    "short_mcp_docs": "MCP ドキュメント",
+    "codex_config": "Codex 代替設定",
+    "opencode_config": "OpenCode 設定",
+    "inspector_note": "Inspector UI を開き、Streamable HTTP トランスポートでホスト済みエンドポイントに接続します。",
+    "interaction_label": "カタログツール操作の例"
+  },
+  "language": {
+    "english": "英語",
+    "chinese": "簡体字中国語",
+    "japanese": "日本語"
+  },
+  "footer": {
+    "version": "バージョン",
+    "updated": "更新日時",
+    "developed_by": "imscraping.ninja が開発"
+  }
+}
diff --git a/locales/zh-CN.json b/locales/zh-CN.json
new file mode 100644
index 0000000..af82583
--- /dev/null
+++ b/locales/zh-CN.json
@@ -0,0 +1,99 @@
+{
+  "nav": {
+    "overview": "概览",
+    "stellar_hosts": "恒星宿主",
+    "exoplanets": "系外行星",
+    "insights": "数据洞察",
+    "docs": "文档",
+    "api": "API",
+    "github_repository": "GitHub 代码仓库",
+    "open_menu": "打开导航菜单",
+    "close_menu": "关闭导航菜单",
+    "mobile_navigation": "移动端导航",
+    "language": "语言"
+  },
+  "home": {
+    "title": "系外行星目录",
+    "description": "通过可搜索的数据表、发现统计和服务端渲染的详情页，探索已确认的系外行星及其宿主恒星。",
+    "hero_title": "🌌 系外行星档案",
+    "hero_subtitle": "探索宇宙：已确认系外行星及其宿主恒星的精确目录",
+    "loading": "正在加载目录数据……",
+    "connection_error": "连接错误",
+    "error_loading": "加载数据时出错",
+    "stellar_systems": "恒星系统",
+    "host_stars_catalogued": "已收录的宿主恒星",
+    "exoplanets": "系外行星",
+    "distinct_planets": "目录中的不同系外行星",
+    "average_temperature": "恒星平均温度",
+    "mean_temperature": "平均有效温度",
+    "average_distance": "平均距离",
+    "mean_distance": "恒星系统平均距离",
+    "live": "实时",
+    "planet_classifications": "行星分类",
+    "planet_classifications_subtitle": "按标准半径分组的不同系外行星",
+    "orbital_periods": "公转周期",
+    "orbital_periods_subtitle": "按标准周期分组的不同系外行星",
+    "discovery_methods": "发现方法",
+    "discovery_methods_subtitle": "按标准发现方法分组的不同系外行星",
+    "discovery_years": "发现年份",
+    "discovery_years_subtitle": "按最早发现年份分组的不同系外行星",
+    "temperature_bands": "行星温度区间",
+    "temperature_bands_subtitle": "按标准平衡温度分组的不同系外行星",
+    "detection_sources": "探测来源",
+    "detection_sources_subtitle": "按发现设施分组的不同系外行星"
+  },
+  "manual": {
+    "examples_title": "打开真实的目录记录",
+    "examples_subtitle": "稳定的路由让页面、导出文件、API 文档和工具配置易于分享。",
+    "stellar_profile": "恒星宿主资料",
+    "stellar_profile_description": "打开 TRAPPIST-1 宿主系统详情页。",
+    "planet_profile": "行星资料",
+    "planet_profile_description": "打开 Kepler-22 b 系外行星详情页。",
+    "host_json": "宿主 JSON",
+    "host_json_description": "下载完整的宿主详情数据。",
+    "host_csv": "宿主 CSV",
+    "host_csv_description": "下载匹配的宿主源数据行。",
+    "planet_json": "行星 JSON",
+    "planet_json_description": "下载完整的行星详情数据。",
+    "planet_csv": "行星 CSV",
+    "planet_csv_description": "下载匹配的行星源数据行。",
+    "rest_api": "REST API",
+    "rest_api_description": "查询数据表、模式、详情、洞察和 SQL 端点。",
+    "mcp_server": "MCP 服务器",
+    "mcp_server_description": "连接 AI 客户端以检查模式并查询目录。",
+    "cli": "CLI",
+    "cli_description": "从终端查询在线或本地数据。",
+    "swagger": "Swagger UI",
+    "swagger_description": "以交互方式浏览 OpenAPI 模式。",
+    "connect_title": "连接 MCP 客户端",
+    "hosted_endpoint": "托管端点为",
+    "read": "阅读",
+    "mcp_introduction": "MCP 入门",
+    "or": "或",
+    "mcp_docs": "Exodata MCP 文档",
+    "copy": "复制",
+    "copied": "已复制",
+    "ask": "提问",
+    "tool": "工具",
+    "sql": "SQL",
+    "result": "结果",
+    "ask_example": "距离最近的已知行星宿主系统，以及各自的距离和行星数量",
+    "result_example": "可用于表格、笔记本或后续查询的结构化数据行",
+    "cli_docs": "CLI 文档",
+    "short_mcp_docs": "MCP 文档",
+    "codex_config": "Codex 备用配置",
+    "opencode_config": "OpenCode 配置",
+    "inspector_note": "打开 Inspector 界面，然后使用 Streamable HTTP 传输连接到托管端点。",
+    "interaction_label": "目录工具交互示例"
+  },
+  "language": {
+    "english": "英语",
+    "chinese": "简体中文",
+    "japanese": "日语"
+  },
+  "footer": {
+    "version": "版本",
+    "updated": "更新时间",
+    "developed_by": "由 imscraping.ninja 开发"
+  }
+}
diff --git a/specs/ctx.md b/specs/ctx.md
index 2ff3542..431c8c7 100644
--- a/specs/ctx.md
+++ b/specs/ctx.md
@@ -1,302 +1,74 @@
 # Current Task Context
 
-## Website Content and Multilingual Layout Plan
-
-This is planning context for a future implementation session. Do not implement
-the website changes from this file until explicitly requested.
-
-Primary direction:
-
-1. First improve the English website content and information architecture.
-2. Then add Chinese and Japanese interface localization on top of the improved
-   English text.
-
-The multilingual work should not start by translating weak or temporary English
-copy. English content becomes the source text, then localized interface strings
-follow.
-
-## English Content First
-
-### Homepage Manual
-
-Implemented on 2026-06-28.
-
-- Added a distinct rounded homepage manual section in
-  `src/components/homepage_manual.rs`, rendered after the detailed overview
-  statistics and reachable from the hero subtitle link.
-- Source prose now lives in `docs/index.md` and is rendered with the existing
-  docs Markdown renderer.
-- The section includes stable catalog example links, hosted MCP setup snippets
-  for Codex, Claude Code, OpenCode, and MCP Inspector, copy buttons, and a
-  compact CLI/MCP interaction card.
-- `docs/mcp.md` now documents only the hosted MCP URL in the connection summary.
-
-### Docs and Public Copy Cleanup
-
-Before translation, tighten the English source copy:
-
-- Make homepage/manual text concise and stable.
-- Make docs index copy suitable as the English source for translation.
-- Keep API/MCP/CLI examples exact and technical.
-- Separate prose that should be translated from command examples, URLs, JSON
-  keys, SQL, and dataset field names that should remain unchanged.
-
-### Blog and Changelog Ideas
-
-Do not add a blog route in the first content pass. Keep these as future content
-ideas:
-
-- story posts about why tables are not enough for exoplanet catalogs
-- agent/MCP usage stories
-- small dataset stories based on insights pages
-- human-readable changelog summaries for major project milestones
-- technical notes about VOTable to Parquet to web/API/CLI flow
-
-`CHANGELOG.md` should remain technical. A future public notes page can summarize
-selected changes in a more narrative format.
-
-### AI Test-Generation Research Idea
-
-Keep this as a research spike, not production automation:
-
-- Explore using `rig.rs` with a DeepSeek Flash model to generate small candidate
-  tests for distinct stellar-system and planet-system features.
-- Generated tests must be reviewed manually before committing.
-- Do not wire model calls into CI in the first experiment.
-- Do not infer behavior from exact fixture numbers when those numbers are only a
-  sampled snapshot of the live dataset.
-
-## Multilingual Interface Plan
-
-Goal: add Chinese and Japanese interface support after the English content pass,
-without turning the first iteration into a full content-management platform.
-
-### Target Languages
-
-- Default: English (`en`)
-- Add: Simplified Chinese (`zh-CN`)
-- Add: Japanese (`ja`)
-
-UI labels:
-
-| Locale | Switcher label | Native label |
-|---|---|---|
-| `en` | EN | English |
-| `zh-CN` | 中文 | 简体中文 |
-| `ja` | 日本語 | 日本語 |
-
-Traditional Chinese is out of scope unless explicitly added later.
-
-### URL Layout
-
-Use prefixed locale routes for localized website pages:
-
-- `/` remains the canonical English homepage.
-- `/zh-CN` renders the Chinese homepage.
-- `/ja` renders the Japanese homepage.
-- English routes remain valid without prefixes:
-  - `/stellarhosts`
-  - `/exoplanets`
-  - `/insights`
-  - `/docs`
-  - detail routes
-- Localized interface routes use the locale prefix:
-  - `/zh-CN/stellarhosts`
-  - `/ja/stellarhosts`
-  - `/zh-CN/exoplanets`
-  - `/ja/exoplanets`
-  - `/zh-CN/insights`
-  - `/ja/insights`
-
-Do not move non-website utility surfaces under locale prefixes:
-
-- keep `/rest/...`
-- keep `/mcp`
-- keep `/swagger-ui`
-- keep `/sitemap-index.xml` and child sitemap routes
-- keep current JSON/CSV export URL behavior
-
-Rationale: prefixed routes are clear for users and SEO, while unprefixed English
-routes preserve existing URLs.
-
-### Locale Detection and Rendering
-
-- Derive the active locale from the first path segment.
-- If the first path segment is `zh-CN` or `ja`, render interface strings in that
-  locale.
-- Otherwise render English.
-- Data rows, entity names, API paths, SQL, JSON keys, CSV headers, and NASA field
-  keys remain unchanged.
-- Detail route identifiers remain original catalog names and are not translated.
-
-The routing layer should avoid duplicating page implementations. Prefer a shared
-locale context/provider that all components can read.
-
-### Language Picker Component
-
-Plan a dedicated language picker component rather than scattering language links
-through the navbar.
-
-Behavior:
-
-- Render compact options: `EN`, `中文`, `日本語`.
-- Show the active locale visually.
-- Map the current page to the same page in the selected locale where possible:
-  - `/exoplanets` -> `/ja/exoplanets`
-  - `/ja/exoplanets` -> `/zh-CN/exoplanets`
-  - `/stellarhosts/TRAPPIST-1` -> `/zh-CN/stellarhosts/TRAPPIST-1`
-- Preserve query strings for table pages when switching languages.
-- Do not prefix external links or utility routes.
-
-Placement:
-
-- Desktop: navbar, compact control near the right side.
-- Mobile: inside the mobile menu, preferably as a segmented row near the bottom.
-
-Accessibility:
-
-- Use a clear accessible label such as `Language`.
-- Each option should expose the native language name, not only the compact label.
-- Keyboard focus and current-state styling should be visible.
-
-### Translation Technology
-
-Use a real i18n crate instead of hand-written string tables if it works cleanly
-with the current Leptos version, SSR, and hydration.
-
-Preferred candidate for the future implementation spike:
-
-- `leptos_i18n`
-
-Why:
-
-- It is designed for Leptos applications.
-- It supports compile-time translation resources and component-level usage.
-- It is a better long-term fit than ad hoc match statements once interface copy
-  spans navbar, tables, details, insights, docs chrome, metadata, and aria labels.
-
-Spike requirements before committing to it:
-
-- Confirm compatibility with the repository's Leptos version.
-- Confirm SSR and hydrate builds both work.
-- Confirm translations can be selected from URL-derived locale state.
-- Confirm metadata/head strings can use localized values.
-- Confirm the generated code does not make simple UI text awkward to maintain.
-
-Fallback if `leptos_i18n` does not fit:
-
-- Use a small internal translation module with semantic keys for v1.
-- Keep the API shaped so it can be replaced by an i18n crate later.
-
-Do not translate directly by using English strings as lookup keys. Use semantic
-keys or generated typed accessors so English copy can be edited without breaking
-translations.
-
-### Translation Surface
-
-Translate interface chrome and project-authored prose first:
-
-- navbar labels, mobile menu labels, aria labels
-- language picker labels
-- homepage hero/manual text and stat labels
-- loading, error, empty, and not-found states
-- table page headings and pagination text
-- column selector controls
-- insight page headings, cards, empty states, and explanatory text
-- detail page section headings, provenance/download controls, and summary labels
-- docs registry titles/descriptions and short localized docs summaries
-
-Do not translate source data values in v1:
-
-- planet names, stellar host names, system names
-- discovery methods, facilities, references, aliases, and record values
-- raw column keys such as `pl_name`, `hostname`, `st_teff`, and `sy_dist`
-- SQL examples, API paths, CLI commands, JSON keys, CSV headers
-
-Scientific units stay unchanged in v1: `K`, `pc`, `R⊕`, `M⊕`, `R☉`.
-
-### Docs Content
-
-Use separate Markdown files only for prose-heavy translated docs.
-
-Suggested future layout:
-
-```text
-docs/
-├── about.md
-├── api.md
-├── cli.md
-├── mcp.md
-└── i18n/
-    ├── zh-CN/
-    │   ├── about.md
-    │   ├── api.md
-    │   ├── cli.md
-    │   └── mcp.md
-    └── ja/
-        ├── about.md
-        ├── api.md
-        ├── cli.md
-        └── mcp.md
-```
-
-For the first localized docs pass, short localized summaries are enough. They
-can link to full English technical docs until full translations are ready.
-
-### SEO and Metadata
-
-- Set `<html lang>` from the active locale.
-- Canonical URLs should point to the active localized page.
-- Add `hreflang` alternates for English, Chinese, and Japanese equivalents.
-- Include localized static routes in the sitemap after route behavior is stable.
-- Do not add localized copies of every detail route to the sitemap in v1.
-- Keep existing English detail routes as the primary entity URLs.
-
-### Layout Requirements
-
-- Use compact labels in the language picker to avoid crowding the navbar.
-- Avoid fixed-width text containers for translated copy.
-- Check Chinese and Japanese line wrapping in:
-  - homepage cards/manual section
-  - table controls and pagination
-  - column selector
-  - insight cards
-  - detail-page download buttons
-- Preserve readable density. The localized interface should not become a separate
-  visual design.
-
-### Suggested Rollout
-
-1. Polish English homepage/manual/docs source copy.
-2. Add locale route parsing, locale context, language picker, and localized href
-   generation while still rendering English strings.
-3. Integrate the chosen i18n approach and translate global navigation plus common
-   states.
-4. Translate homepage manual, table controls, insight chrome, and detail chrome.
-5. Add localized docs summaries.
-6. Add localized metadata, `hreflang`, and sitemap entries.
-
-### Verification
-
-Unit tests:
-
-- locale parsing from path
-- localized href generation with query-string preservation
-- utility routes remain unprefixed
-- canonical and alternate URL generation
-- docs link rewriting with locale prefixes
-
-SSR/manual checks:
-
-- `/`, `/zh-CN`, `/ja`
-- `/zh-CN/stellarhosts`, `/ja/exoplanets`
-- localized detail route switching
-- table query state survives language switching
-- `/rest`, `/mcp`, `/swagger-ui`, and export URLs remain unprefixed
-
-Browser checks:
-
-- desktop navbar does not overflow
-- mobile language picker is usable
-- CN/JP text does not overlap in cards, table controls, pagination, and detail
-  action buttons
+## Localization Status
+
+The English homepage content pass and the first localization pass are complete.
+The implementation uses `leptos_i18n` with semantic keys and compile-time JSON
+resources for:
+
+- English (`en`) — default, unprefixed routes
+- Simplified Chinese (`zh-CN`) — `/zh-CN/...`
+- Japanese (`ja`) — `/ja/...`
+
+Traditional Chinese is out of scope unless explicitly requested.
+
+## Completed
+
+- Added locale-prefixed aliases for website routes without duplicating page
+  implementations.
+- Added the desktop navbar and mobile-menu language switcher with current-locale
+  styling, accessible labels, and same-page switching.
+- Preserved the current path, query string, and fragment when switching locale.
+- Kept `/rest`, `/mcp`, `/swagger-ui`, sitemap routes, and JSON/CSV exports
+  unprefixed.
+- Translated global navigation, mobile controls, footer text, homepage metadata,
+  hero, loading/error states, statistics headings, and the complete homepage
+  manual.
+- Added Chinese and Japanese homepage Markdown under `docs/i18n/`.
+- Set `<html lang>` from the URL locale and added homepage canonical and
+  `hreflang` metadata.
+- Added `/zh-CN` and `/ja` to the static sitemap; localized table/detail routes
+  are intentionally not advertised yet.
+- Added tests for locale parsing, localized URL generation, URL-state
+  preservation, utility/export exclusions, and localized sitemap entries.
+- Verified formatting, Clippy, workspace tests, and the combined SSR/WASM
+  `cargo leptos build`.
+
+## Stable Rules
+
+- The URL is the only locale source. Do not add cookie, browser-language, or
+  `Accept-Language` redirects.
+- Unprefixed routes always render English; do not introduce `/en/...` routes.
+- Never translate catalog values, entity names, route identifiers, NASA field
+  keys, SQL, commands, API paths, JSON/CSV keys, or scientific units.
+- Keep stable homepage fragments identical across locales:
+  `#mcp-exoplanet-data`, `#catalog-examples-title`, and `#mcp-setup-title`.
+- Use locale resources for short interface strings and separate Markdown files
+  for prose-heavy translated content.
+
+## Deferred Translation Work
+
+The following page-specific content still renders in English, even under locale
+prefixes:
+
+- table headings, filters, column selector, pagination, and table states
+- stellar-host and exoplanet detail-page chrome
+- insight overview/detail chrome and explanatory text
+- not-found and shared application error/empty states
+- technical docs content and docs registry metadata
+- non-homepage localized metadata, canonical URLs, and `hreflang`
+
+Do not add these partially translated routes to the sitemap. Add localized
+sitemap entries only as each page surface is translated and receives correct
+localized metadata.
+
+## Recommended Next Pass
+
+1. Translate shared table controls and states while leaving dataset values and
+   column keys unchanged.
+2. Ensure table navigation, pagination, filters, and entity links retain the
+   active locale prefix and query state.
+3. Translate detail and insight chrome.
+4. Add localized docs summaries, then full translated docs only when reviewed.
+5. Expand canonical, `hreflang`, and sitemap coverage alongside each completed
+   surface.
diff --git a/specs/web-frontend.md b/specs/web-frontend.md
index fedec30..0691f98 100644
--- a/specs/web-frontend.md
+++ b/specs/web-frontend.md
@@ -11,6 +11,19 @@ The frontend is a reactive single-page application (SPA) built with:
 - **Hydration** - Client-side interactivity after SSR
 - **WASM** - Client-side code compiled to WebAssembly
 
+## Localization
+
+The website uses `leptos_i18n` with compile-time JSON resources for English,
+Simplified Chinese, and Japanese. English is the default and remains
+unprefixed; `/zh-CN` and `/ja` select the other locales. Locale-prefixed aliases
+exist for website routes, while REST, MCP, Swagger, sitemap, and export URLs
+remain unprefixed.
+
+The active locale is derived only from the URL. The language switcher preserves
+the current path, query string, and fragment. In the first localization pass,
+global navigation, the footer, and the homepage are translated; table, detail,
+insight, and technical documentation content remains English.
+
 ## Architecture
 
 ```
diff --git a/src/app.rs b/src/app.rs
index 960a74d..5fd7698 100644
--- a/src/app.rs
+++ b/src/app.rs
@@ -14,6 +14,7 @@ use crate::components::{
 use crate::error_template::{AppError, ErrorTemplate};
 use crate::metadata::{METADATA_SCRIPT_ID, provide_app_metadata_store};
 use crate::metadata_helpers::SITE_NAME;
+use crate::{i18n::*, locale::locale_from_path};
 
 use leptos::error::Errors;
 use leptos::hydration::HydrationScripts;
@@ -66,19 +67,21 @@ pub fn App() -> impl IntoView {
 
         <Title text=SITE_NAME/>
 
-        // content for this welcome page
-        <Router>
-            // Navigation bar (must be inside Router to use location)
-            <Navbar/>
+        <I18nContextProvider enable_cookie=false set_lang_attr_on_html=true>
+            // content for this welcome page
+            <Router>
+                <LocaleSync/>
+                // Navigation bar (must be inside Router to use location)
+                <Navbar/>
 
-            <Routes fallback=|| {
-                let mut outside_errors = Errors::default();
-                outside_errors.insert_with_default_key(AppError::NotFound);
-                view! {
-                    <ErrorTemplate outside_errors/>
-                }
-                .into_view()
-            }>
+                <Routes fallback=|| {
+                    let mut outside_errors = Errors::default();
+                    outside_errors.insert_with_default_key(AppError::NotFound);
+                    view! {
+                        <ErrorTemplate outside_errors/>
+                    }
+                    .into_view()
+                }>
                 <Route path=StaticSegment("") view={Lazy::<OverviewLazy>::new()} ssr=SsrMode::Async/>
                 <Route
                     path=StaticSegment("stellarhosts")
@@ -97,9 +100,45 @@ pub fn App() -> impl IntoView {
                 <Route path=StaticSegment("docs") view={Lazy::<DocsLazy>::new()} ssr=SsrMode::Async/>
                 <Route path=path!("/docs/:slug") view={Lazy::<DocsLazy>::new()} ssr=SsrMode::Async/>
                 <Route path=StaticSegment("about") view={Lazy::<AboutLazy>::new()} ssr=SsrMode::Async/>
-            </Routes>
+                    <Route path=StaticSegment("zh-CN") view={Lazy::<OverviewLazy>::new()} ssr=SsrMode::Async/>
+                    <Route path=path!("/zh-CN/stellarhosts") view={Lazy::<StellarHostsTableLazy>::new()} ssr=SsrMode::Async/>
+                    <Route path=path!("/zh-CN/stellarhosts/:hostname") view={Lazy::<StellarHostDetailLazy>::new()} ssr=SsrMode::Async/>
+                    <Route path=path!("/zh-CN/exoplanets") view={Lazy::<ExoplanetsTableLazy>::new()} ssr=SsrMode::Async/>
+                    <Route path=path!("/zh-CN/exoplanets/:pl_name") view={Lazy::<ExoplanetDetailLazy>::new()} ssr=SsrMode::Async/>
+                    <Route path=path!("/zh-CN/insights") view={Lazy::<InsightsLazy>::new()} ssr=SsrMode::Async/>
+                    <Route path=path!("/zh-CN/insights/:slug") view={Lazy::<InsightDetailLazy>::new()} ssr=SsrMode::Async/>
+                    <Route path=path!("/zh-CN/docs") view={Lazy::<DocsLazy>::new()} ssr=SsrMode::Async/>
+                    <Route path=path!("/zh-CN/docs/:slug") view={Lazy::<DocsLazy>::new()} ssr=SsrMode::Async/>
+                    <Route path=path!("/zh-CN/about") view={Lazy::<AboutLazy>::new()} ssr=SsrMode::Async/>
+                    <Route path=StaticSegment("ja") view={Lazy::<OverviewLazy>::new()} ssr=SsrMode::Async/>
+                    <Route path=path!("/ja/stellarhosts") view={Lazy::<StellarHostsTableLazy>::new()} ssr=SsrMode::Async/>
+                    <Route path=path!("/ja/stellarhosts/:hostname") view={Lazy::<StellarHostDetailLazy>::new()} ssr=SsrMode::Async/>
+                    <Route path=path!("/ja/exoplanets") view={Lazy::<ExoplanetsTableLazy>::new()} ssr=SsrMode::Async/>
+                    <Route path=path!("/ja/exoplanets/:pl_name") view={Lazy::<ExoplanetDetailLazy>::new()} ssr=SsrMode::Async/>
+                    <Route path=path!("/ja/insights") view={Lazy::<InsightsLazy>::new()} ssr=SsrMode::Async/>
+                    <Route path=path!("/ja/insights/:slug") view={Lazy::<InsightDetailLazy>::new()} ssr=SsrMode::Async/>
+                    <Route path=path!("/ja/docs") view={Lazy::<DocsLazy>::new()} ssr=SsrMode::Async/>
+                    <Route path=path!("/ja/docs/:slug") view={Lazy::<DocsLazy>::new()} ssr=SsrMode::Async/>
+                    <Route path=path!("/ja/about") view={Lazy::<AboutLazy>::new()} ssr=SsrMode::Async/>
+                </Routes>
 
-            <VersionFooter/>
-        </Router>
+                <VersionFooter/>
+            </Router>
+        </I18nContextProvider>
     }
 }
+
+#[component]
+fn LocaleSync() -> impl IntoView {
+    use leptos_router::hooks::use_location;
+
+    let location = use_location();
+    let i18n = use_i18n();
+    i18n.set_locale_untracked(locale_from_path(
+        &location.pathname.get_untracked(),
+    ));
+
+    Effect::new(move |_| {
+        i18n.set_locale(locale_from_path(&location.pathname.get()));
+    });
+}
diff --git a/src/components/footer.rs b/src/components/footer.rs
index eafda15..5222b7a 100644
--- a/src/components/footer.rs
+++ b/src/components/footer.rs
@@ -1,5 +1,7 @@
 use leptos::prelude::*;
 
+use crate::i18n::*;
+
 const APP_VERSION: &str = env!("CARGO_PKG_VERSION");
 const BUILD_TIMESTAMP: &str = match option_env!("BUILD_TIMESTAMP") {
     Some(value) => value,
@@ -8,15 +10,16 @@ const BUILD_TIMESTAMP: &str = match option_env!("BUILD_TIMESTAMP") {
 
 #[component]
 pub fn VersionFooter() -> impl IntoView {
+    let i18n = use_i18n();
     view! {
         <footer class="w-full border-t border-slate-800 bg-slate-950">
             <div class="mx-auto flex max-w-7xl flex-col items-center justify-center gap-2 px-4 py-3 sm:flex-row sm:gap-4">
                 <span class="inline-flex items-center gap-2 rounded-full border border-cyan-400/30 bg-slate-900 px-3 py-1 text-sm font-medium text-slate-100">
-                    <span class="text-slate-400">"Version"</span>
+                    <span class="text-slate-400">{t!(i18n, footer.version)}</span>
                     <span class="font-semibold text-cyan-300">{APP_VERSION}</span>
                 </span>
                 <span class="inline-flex items-center gap-2 rounded-full border border-slate-700 bg-slate-900 px-3 py-1 text-sm font-medium text-slate-100">
-                    <span class="text-slate-400">"Updated"</span>
+                    <span class="text-slate-400">{t!(i18n, footer.updated)}</span>
                     <span class="font-semibold text-slate-200">{BUILD_TIMESTAMP}</span>
                 </span>
                 <a
@@ -25,7 +28,7 @@ pub fn VersionFooter() -> impl IntoView {
                     rel="noopener noreferrer"
                     class="text-sm font-medium text-slate-200 hover:text-cyan-300"
                 >
-                    "Developed by imscraping.ninja"
+                    {t!(i18n, footer.developed_by)}
                 </a>
             </div>
         </footer>
diff --git a/src/components/homepage_manual.rs b/src/components/homepage_manual.rs
index 1ec06d5..41ffc79 100644
--- a/src/components/homepage_manual.rs
+++ b/src/components/homepage_manual.rs
@@ -1,20 +1,29 @@
 use leptos::prelude::*;
 
 use crate::components::docs::render::render_markdown;
+use crate::i18n::*;
+use crate::locale::localized_path;
 
-const MANUAL_MARKDOWN: &str = include_str!("../../docs/index.md");
-const HOST_NAME: &str = "TRAPPIST-1";
+const MANUAL_MARKDOWN_EN: &str = include_str!("../../docs/index.md");
+const MANUAL_MARKDOWN_ZH_CN: &str =
+    include_str!("../../docs/i18n/zh-CN/index.md");
+const MANUAL_MARKDOWN_JA: &str = include_str!("../../docs/i18n/ja/index.md");
 const HOST_PATH: &str = "/stellarhosts/TRAPPIST-1";
-const PLANET_NAME: &str = "Kepler-22 b";
 const PLANET_PATH: &str = "/exoplanets/Kepler-22%20b";
 const MCP_ENDPOINT: &str = "https://exodata.space/mcp";
 
 #[component]
 pub fn HomepageManual() -> impl IntoView {
-    let html = render_markdown(MANUAL_MARKDOWN);
+    let locale = use_i18n().get_locale_untracked();
+    let markdown = match locale {
+        Locale::en => MANUAL_MARKDOWN_EN,
+        Locale::zh_CN => MANUAL_MARKDOWN_ZH_CN,
+        Locale::ja => MANUAL_MARKDOWN_JA,
+    };
+    let html = render_markdown(markdown);
 
     view! {
-        <section id="homepage-manual" class="homepage-manual" aria-labelledby="homepage-manual-title">
+        <section id="mcp-exoplanet-data" class="homepage-manual" aria-labelledby="homepage-manual-title">
             <div class="homepage-manual__container">
                 <div class="homepage-manual__intro">
                     <article
@@ -34,63 +43,67 @@ pub fn HomepageManual() -> impl IntoView {
 
 #[component]
 fn ExampleLinks() -> impl IntoView {
+    let i18n = use_i18n();
+    let locale = i18n.get_locale_untracked();
     view! {
         <div class="homepage-manual__examples" aria-labelledby="catalog-examples-title">
             <div class="homepage-manual__section-heading">
-                <h2 id="catalog-examples-title">"Open a real catalog record"</h2>
-                <p>"Stable routes make pages, exports, API docs, and tool setup easy to share."</p>
+                <h2 id="catalog-examples-title">
+                    <a href="#catalog-examples-title">{t!(i18n, manual.examples_title)}</a>
+                </h2>
+                <p>{t!(i18n, manual.examples_subtitle)}</p>
             </div>
 
             <div class="homepage-manual__link-grid">
                 <ExampleLink
-                    href=HOST_PATH
-                    title="Stellar host profile"
-                    description=format!("Open the {HOST_NAME} host-system detail page.")
+                    href=localized_path(HOST_PATH, locale)
+                    title=t_string!(i18n, manual.stellar_profile)
+                    description=t_string!(i18n, manual.stellar_profile_description)
                 />
                 <ExampleLink
-                    href=PLANET_PATH
-                    title="Planet profile"
-                    description=format!("Open the {PLANET_NAME} exoplanet detail page.")
+                    href=localized_path(PLANET_PATH, locale)
+                    title=t_string!(i18n, manual.planet_profile)
+                    description=t_string!(i18n, manual.planet_profile_description)
                 />
                 <ExampleLink
-                    href="/stellarhosts/TRAPPIST-1.json"
-                    title="Host JSON"
-                    description="Download the full host detail payload.".to_string()
+                    href="/stellarhosts/TRAPPIST-1.json".to_string()
+                    title=t_string!(i18n, manual.host_json)
+                    description=t_string!(i18n, manual.host_json_description)
                 />
                 <ExampleLink
-                    href="/stellarhosts/TRAPPIST-1.csv"
-                    title="Host CSV"
-                    description="Download matching host source rows.".to_string()
+                    href="/stellarhosts/TRAPPIST-1.csv".to_string()
+                    title=t_string!(i18n, manual.host_csv)
+                    description=t_string!(i18n, manual.host_csv_description)
                 />
                 <ExampleLink
-                    href="/exoplanets/Kepler-22%20b.json"
-                    title="Planet JSON"
-                    description="Download the full planet detail payload.".to_string()
+                    href="/exoplanets/Kepler-22%20b.json".to_string()
+                    title=t_string!(i18n, manual.planet_json)
+                    description=t_string!(i18n, manual.planet_json_description)
                 />
                 <ExampleLink
-                    href="/exoplanets/Kepler-22%20b.csv"
-                    title="Planet CSV"
-                    description="Download matching planet source rows.".to_string()
+                    href="/exoplanets/Kepler-22%20b.csv".to_string()
+                    title=t_string!(i18n, manual.planet_csv)
+                    description=t_string!(i18n, manual.planet_csv_description)
                 />
                 <ExampleLink
-                    href="/docs/api"
-                    title="REST API"
-                    description="Query tables, schemas, details, insights, and SQL endpoints.".to_string()
+                    href=localized_path("/docs/api", locale)
+                    title=t_string!(i18n, manual.rest_api)
+                    description=t_string!(i18n, manual.rest_api_description)
                 />
                 <ExampleLink
-                    href="/docs/mcp"
-                    title="MCP server"
-                    description="Connect an AI client to inspect schema and query the catalog.".to_string()
+                    href=localized_path("/docs/mcp", locale)
+                    title=t_string!(i18n, manual.mcp_server)
+                    description=t_string!(i18n, manual.mcp_server_description)
                 />
                 <ExampleLink
-                    href="/docs/cli"
-                    title="CLI"
-                    description="Query live or local data from the terminal.".to_string()
+                    href=localized_path("/docs/cli", locale)
+                    title=t_string!(i18n, manual.cli)
+                    description=t_string!(i18n, manual.cli_description)
                 />
                 <ExampleLink
-                    href="/swagger-ui"
-                    title="Swagger UI"
-                    description="Explore the OpenAPI schema interactively.".to_string()
+                    href="/swagger-ui".to_string()
+                    title=t_string!(i18n, manual.swagger)
+                    description=t_string!(i18n, manual.swagger_description)
                 />
             </div>
         </div>
@@ -99,9 +112,9 @@ fn ExampleLinks() -> impl IntoView {
 
 #[component]
 fn ExampleLink(
-    href: &'static str,
+    href: String,
     title: &'static str,
-    description: String,
+    description: &'static str,
 ) -> impl IntoView {
     view! {
         <a class="homepage-manual-link" href=href>
@@ -113,23 +126,27 @@ fn ExampleLink(
 
 #[component]
 fn McpSetup() -> impl IntoView {
+    let i18n = use_i18n();
+    let docs_href = localized_path("/docs/mcp", i18n.get_locale_untracked());
     view! {
         <div class="homepage-manual__mcp" aria-labelledby="mcp-setup-title">
             <div class="homepage-manual__section-heading">
-                <h2 id="mcp-setup-title">"Connect an MCP client"</h2>
+                <h2 id="mcp-setup-title">
+                    <a href="#mcp-setup-title">{t!(i18n, manual.connect_title)}</a>
+                </h2>
                 <p>
-                    "The hosted endpoint is "
+                    {t!(i18n, manual.hosted_endpoint)} " "
                     <code>{MCP_ENDPOINT}</code>
-                    ". Read the "
+                    ". " {t!(i18n, manual.read)} " "
                     <a
                         href="https://modelcontextprotocol.io/docs/getting-started/intro"
                         target="_blank"
                         rel="noopener noreferrer"
                     >
-                        "MCP introduction"
+                        {t!(i18n, manual.mcp_introduction)}
                     </a>
-                    " or the "
-                    <a href="/docs/mcp">"Exodata MCP docs"</a>
+                    " " {t!(i18n, manual.or)} " "
+                    <a href=docs_href>{t!(i18n, manual.mcp_docs)}</a>
                     "."
                 </p>
             </div>
@@ -142,7 +159,7 @@ fn McpSetup() -> impl IntoView {
     --url https://exodata.space/mcp"
                 />
                 <CommandBox
-                    label="Codex config fallback"
+                    label=t_string!(i18n, manual.codex_config)
                     language="toml"
                     code="[mcp_servers.exodata]
     url = \"https://exodata.space/mcp\""
@@ -162,7 +179,7 @@ fn McpSetup() -> impl IntoView {
     --url https://exodata.space/mcp"
                 />
                 <CommandBox
-                    label="OpenCode config"
+                    label=t_string!(i18n, manual.opencode_config)
                     language="json"
                     code="{
   \"$schema\": \"https://opencode.ai/config.json\",
@@ -179,7 +196,7 @@ fn McpSetup() -> impl IntoView {
                     label="MCP Inspector"
                     language="bash"
                     code="npx @modelcontextprotocol/inspector"
-                    note="Open the Inspector UI, then connect to the hosted endpoint with Streamable HTTP transport."
+                    note=t_string!(i18n, manual.inspector_note)
                 />
             </div>
         </div>
@@ -193,6 +210,7 @@ fn CommandBox(
     code: &'static str,
     #[prop(optional)] note: Option<&'static str>,
 ) -> impl IntoView {
+    let i18n = use_i18n();
     let (copied, set_copied) = signal(false);
 
     view! {
@@ -204,7 +222,11 @@ fn CommandBox(
                     class="homepage-command-box__copy"
                     on:click=move |_| copy_code_to_clipboard(code, set_copied)
                 >
-                    {move || if copied.get() { "Copied" } else { "Copy" }}
+                    {move || if copied.get() {
+                        t_string!(i18n, manual.copied)
+                    } else {
+                        t_string!(i18n, manual.copy)
+                    }}
                 </button>
             </div>
             <pre><code class=format!("language-{language}")>{code}</code></pre>
@@ -215,35 +237,37 @@ fn CommandBox(
 
 #[component]
 fn AgentInteractionCard() -> impl IntoView {
+    let i18n = use_i18n();
+    let locale = i18n.get_locale_untracked();
     view! {
-        <aside class="homepage-agent-card" aria-label="Example catalog tool interaction">
+        <aside class="homepage-agent-card" aria-label=t_string!(i18n, manual.interaction_label)>
             <div class="homepage-agent-card__header">
                 <span>"exodata"</span>
                 <span>"CLI / MCP"</span>
             </div>
             <dl class="homepage-agent-card__flow">
                 <div>
-                    <dt>"Ask"</dt>
-                    <dd>"nearest known planet-hosting systems with distance and planet count"</dd>
+                    <dt>{t!(i18n, manual.ask)}</dt>
+                    <dd>{t!(i18n, manual.ask_example)}</dd>
                 </div>
                 <div>
-                    <dt>"Tool"</dt>
+                    <dt>{t!(i18n, manual.tool)}</dt>
                     <dd>"describe_catalog -> query_catalog"</dd>
                 </div>
                 <div>
-                    <dt>"SQL"</dt>
+                    <dt>{t!(i18n, manual.sql)}</dt>
                     <dd>
                         <code>"SELECT hostname, sy_dist, sy_pnum FROM stellarhosts WHERE sy_dist IS NOT NULL ORDER BY sy_dist LIMIT 5"</code>
                     </dd>
                 </div>
                 <div>
-                    <dt>"Result"</dt>
-                    <dd>"structured rows ready for a table, notebook, or follow-up query"</dd>
+                    <dt>{t!(i18n, manual.result)}</dt>
+                    <dd>{t!(i18n, manual.result_example)}</dd>
                 </div>
             </dl>
             <div class="homepage-agent-card__links">
-                <a href="/docs/cli">"CLI docs"</a>
-                <a href="/docs/mcp">"MCP docs"</a>
+                <a href=localized_path("/docs/cli", locale)>{t!(i18n, manual.cli_docs)}</a>
+                <a href=localized_path("/docs/mcp", locale)>{t!(i18n, manual.short_mcp_docs)}</a>
             </div>
         </aside>
     }
diff --git a/src/components/navbar.rs b/src/components/navbar.rs
index 889d5f7..fe08f2f 100644
--- a/src/components/navbar.rs
+++ b/src/components/navbar.rs
@@ -3,15 +3,24 @@ use leptos::web_sys::KeyboardEvent;
 use leptos_router::components::A;
 use leptos_router::hooks::use_location;
 
+use crate::i18n::*;
+use crate::locale::{
+    locale_from_path, localized_path, localized_url, strip_locale_prefix,
+};
+
 #[component]
 pub fn Navbar() -> impl IntoView {
     let location = use_location();
+    let i18n = use_i18n();
     let pathname = move || location.pathname.get();
-    let is_stellarhosts = move || pathname().starts_with("/stellarhosts");
-    let is_exoplanets = move || pathname().starts_with("/exoplanets");
-    let is_insights = move || pathname().starts_with("/insights");
+    let current_path = move || strip_locale_prefix(&pathname()).to_string();
+    let current_locale = move || locale_from_path(&pathname());
+    let is_stellarhosts = move || current_path().starts_with("/stellarhosts");
+    let is_exoplanets = move || current_path().starts_with("/exoplanets");
+    let is_insights = move || current_path().starts_with("/insights");
     let is_docs = move || {
-        pathname().starts_with("/docs") || pathname().starts_with("/about")
+        current_path().starts_with("/docs")
+            || current_path().starts_with("/about")
     };
 
     // Mobile menu state
@@ -38,7 +47,7 @@ pub fn Navbar() -> impl IntoView {
         <nav class="bg-slate-900/80 backdrop-blur-sm border-b border-purple-500/20 sticky top-0 z-50">
             <div class="container mx-auto px-4">
                 <div class="flex justify-between items-center h-16">
-                    <A href="/" attr:class="flex items-center">
+                    <A href=move || localized_path("/", current_locale()) attr:class="flex items-center">
                         <span class="text-xl md:text-2xl font-bold text-transparent bg-clip-text bg-gradient-to-r from-blue-400 to-purple-400">
                             "🪐 Exoplanets"
                         </span>
@@ -47,7 +56,7 @@ pub fn Navbar() -> impl IntoView {
                     // Desktop Navigation (hidden on mobile)
                     <div class="hidden md:flex space-x-2 text-gray-300">
                         <A
-                            href="/stellarhosts"
+                            href=move || localized_path("/stellarhosts", current_locale())
                             attr:class=move || {
                                 if is_stellarhosts() {
                                     active_class
@@ -56,11 +65,11 @@ pub fn Navbar() -> impl IntoView {
                                 }
                             }
                         >
-                            "Stellar Hosts"
+                            {t!(i18n, nav.stellar_hosts)}
                         </A>
 
                         <A
-                            href="/exoplanets"
+                            href=move || localized_path("/exoplanets", current_locale())
                             attr:class=move || {
                                 if is_exoplanets() {
                                     active_class
@@ -69,11 +78,11 @@ pub fn Navbar() -> impl IntoView {
                                 }
                             }
                         >
-                            "Exoplanets"
+                            {t!(i18n, nav.exoplanets)}
                         </A>
 
                         <A
-                            href="/insights"
+                            href=move || localized_path("/insights", current_locale())
                             attr:class=move || {
                                 if is_insights() {
                                     active_class
@@ -82,11 +91,11 @@ pub fn Navbar() -> impl IntoView {
                                 }
                             }
                         >
-                            "Insights"
+                            {t!(i18n, nav.insights)}
                         </A>
 
                         <A
-                            href="/docs"
+                            href=move || localized_path("/docs", current_locale())
                             attr:class=move || {
                                 if is_docs() {
                                     active_class
@@ -95,7 +104,7 @@ pub fn Navbar() -> impl IntoView {
                                 }
                             }
                         >
-                            "Docs"
+                            {t!(i18n, nav.docs)}
                         </A>
 
                         <a
@@ -103,7 +112,7 @@ pub fn Navbar() -> impl IntoView {
                             class=link_class
                             target="_blank"
                         >
-                            "API"
+                            {t!(i18n, nav.api)}
                         </a>
 
                         <a
@@ -111,17 +120,18 @@ pub fn Navbar() -> impl IntoView {
                             class=icon_link_class
                             target="_blank"
                             rel="noopener noreferrer"
-                            aria-label="GitHub repository"
-                            title="GitHub repository"
+                            aria-label=move || t_string!(i18n, nav.github_repository)
+                            title=move || t_string!(i18n, nav.github_repository)
                         >
                             {github_icon()}
                         </a>
+                        <LanguageSwitcher/>
                     </div>
 
                     // Hamburger Button (visible on mobile only)
                     <button
                         class="md:hidden flex items-center justify-center w-10 h-10 rounded-lg hover:bg-white/10 transition-colors"
-                        aria-label="Open navigation menu"
+                        aria-label=move || t_string!(i18n, nav.open_menu)
                         aria-expanded=move || mobile_menu_open.get()
                         aria-controls="mobile-menu"
                         on:click=move |_| set_mobile_menu_open.set(true)
@@ -146,7 +156,7 @@ pub fn Navbar() -> impl IntoView {
                     id="mobile-menu"
                     class="relative z-10 flex flex-col h-full"
                     role="navigation"
-                    aria-label="Mobile navigation"
+                    aria-label=move || t_string!(i18n, nav.mobile_navigation)
                     on:keydown=move |e: KeyboardEvent| {
                         if e.key() == "Escape" {
                             set_mobile_menu_open.set(false);
@@ -160,7 +170,7 @@ pub fn Navbar() -> impl IntoView {
                         </span>
                         <button
                             class="flex items-center justify-center w-10 h-10 rounded-lg hover:bg-white/10 transition-colors"
-                            aria-label="Close navigation menu"
+                            aria-label=move || t_string!(i18n, nav.close_menu)
                             on:click=move |_| set_mobile_menu_open.set(false)
                         >
                             {close_icon()}
@@ -170,44 +180,44 @@ pub fn Navbar() -> impl IntoView {
                     // Navigation Links
                     <div class="flex-1 flex flex-col items-center justify-center space-y-4 px-6">
                         <A
-                            href="/"
+                            href=move || localized_path("/", current_locale())
                             attr:class=move || {
-                                if pathname() == "/" { mobile_active_class } else { mobile_link_class }
+                                if current_path() == "/" { mobile_active_class } else { mobile_link_class }
                             }
                         >
-                            "Overview"
+                            {t!(i18n, nav.overview)}
                         </A>
                         <A
-                            href="/stellarhosts"
+                            href=move || localized_path("/stellarhosts", current_locale())
                             attr:class=move || {
                                 if is_stellarhosts() { mobile_active_class } else { mobile_link_class }
                             }
                         >
-                            "Stellar Hosts"
+                            {t!(i18n, nav.stellar_hosts)}
                         </A>
                         <A
-                            href="/exoplanets"
+                            href=move || localized_path("/exoplanets", current_locale())
                             attr:class=move || {
                                 if is_exoplanets() { mobile_active_class } else { mobile_link_class }
                             }
                         >
-                            "Exoplanets"
+                            {t!(i18n, nav.exoplanets)}
                         </A>
                         <A
-                            href="/insights"
+                            href=move || localized_path("/insights", current_locale())
                             attr:class=move || {
                                 if is_insights() { mobile_active_class } else { mobile_link_class }
                             }
                         >
-                            "Insights"
+                            {t!(i18n, nav.insights)}
                         </A>
                         <A
-                            href="/docs"
+                            href=move || localized_path("/docs", current_locale())
                             attr:class=move || {
                                 if is_docs() { mobile_active_class } else { mobile_link_class }
                             }
                         >
-                            "Docs"
+                            {t!(i18n, nav.docs)}
                         </A>
 
                         <a
@@ -215,8 +225,9 @@ pub fn Navbar() -> impl IntoView {
                             class=mobile_link_class
                             target="_blank"
                         >
-                            "API"
+                            {t!(i18n, nav.api)}
                         </a>
+                        <LanguageSwitcher/>
 
                         <a
                             href="https://github.com/oiwn/exoplanets-catalog"
@@ -236,6 +247,61 @@ pub fn Navbar() -> impl IntoView {
     }
 }
 
+#[component]
+fn LanguageSwitcher() -> impl IntoView {
+    let location = use_location();
+    let i18n = use_i18n();
+    let current_locale = move || locale_from_path(&location.pathname.get());
+    let href_for = move |locale| {
+        localized_url(
+            &location.pathname.get(),
+            &location.search.get(),
+            &location.hash.get(),
+            locale,
+        )
+    };
+    let option_class = move |locale| {
+        if current_locale() == locale {
+            "rounded-md bg-purple-500/25 px-2.5 py-1.5 text-xs font-semibold text-purple-200"
+        } else {
+            "rounded-md px-2.5 py-1.5 text-xs font-semibold text-slate-300 transition-colors hover:bg-white/10 hover:text-white"
+        }
+    };
+
+    view! {
+        <div
+            class="flex items-center gap-0.5 rounded-lg border border-slate-700 bg-slate-950/60 p-1"
+            role="group"
+            aria-label=move || t_string!(i18n, nav.language)
+        >
+            <A
+                href=move || href_for(Locale::en)
+                attr:class=move || option_class(Locale::en)
+                attr:lang="en"
+                attr:title="English"
+            >
+                "EN"
+            </A>
+            <A
+                href=move || href_for(Locale::zh_CN)
+                attr:class=move || option_class(Locale::zh_CN)
+                attr:lang="zh-CN"
+                attr:title="简体中文"
+            >
+                "中文"
+            </A>
+            <A
+                href=move || href_for(Locale::ja)
+                attr:class=move || option_class(Locale::ja)
+                attr:lang="ja"
+                attr:title="日本語"
+            >
+                "日本語"
+            </A>
+        </div>
+    }
+}
+
 fn hamburger_icon() -> impl IntoView {
     view! {
         <svg
diff --git a/src/components/overview.rs b/src/components/overview.rs
index ff85a41..de68965 100644
--- a/src/components/overview.rs
+++ b/src/components/overview.rs
@@ -3,9 +3,8 @@ use leptos_meta::{Link, Meta, Title};
 use leptos_router::LazyRoute;
 use leptos_router::lazy_route;
 
-use crate::metadata_helpers::{
-    canonical_url, overview_description, overview_title,
-};
+use crate::metadata_helpers::{SITE_URL, canonical_url, title_with_site};
+use crate::{i18n::*, locale::localized_path};
 // Import server function and types - #[server] macro handles client/server compilation
 use crate::components::homepage_manual::HomepageManual;
 use crate::server::functions::{DataStats, get_stats};
@@ -29,14 +28,21 @@ impl LazyRoute for OverviewLazy {
 
 #[component]
 pub fn OverviewPage() -> impl IntoView {
+    let i18n = use_i18n();
+    let locale = i18n.get_locale_untracked();
+    let canonical_path = localized_path("/", locale);
     // Create a resource that calls the server function
     let stats_resource =
         Resource::new(move || (), move |_| async move { get_stats().await });
 
     view! {
-        <Title text=overview_title()/>
-        <Meta name="description" content=overview_description()/>
-        <Link rel="canonical" href=canonical_url("/")/>
+        <Title text=title_with_site(t_string!(i18n, home.title))/>
+        <Meta name="description" content=t_string!(i18n, home.description)/>
+        <Link rel="canonical" href=canonical_url(&canonical_path)/>
+        <Link rel="alternate" hreflang="en" href=format!("{SITE_URL}/")/>
+        <Link rel="alternate" hreflang="zh-CN" href=format!("{SITE_URL}/zh-CN")/>
+        <Link rel="alternate" hreflang="ja" href=format!("{SITE_URL}/ja")/>
+        <Link rel="alternate" hreflang="x-default" href=format!("{SITE_URL}/")/>
         <StructuredData value=website_schema()/>
         <div class="min-h-screen bg-gradient-to-br from-slate-900 via-purple-900 to-slate-900">
             // Header with cosmic background
@@ -46,13 +52,13 @@ pub fn OverviewPage() -> impl IntoView {
                 <div class="container mx-auto px-4 py-16 relative">
                     <div class="text-center space-y-4">
                         <h1 class="text-5xl md:text-6xl font-bold text-transparent bg-clip-text bg-gradient-to-r from-blue-400 via-purple-400 to-pink-400 animate-pulse">
-                            "🌌 Exoplanet Archive"
+                            {t!(i18n, home.hero_title)}
                         </h1>
                         <a
-                            href="#homepage-manual"
+                            href="#mcp-exoplanet-data"
                             class="block text-xl text-gray-300 max-w-2xl mx-auto transition-colors hover:text-white focus:outline-none focus:ring-2 focus:ring-purple-400 rounded-lg"
                         >
-                            "Exploring the cosmos: A comprehensive catalog of confirmed exoplanets and their host stars"
+                            {t!(i18n, home.hero_subtitle)}
                         </a>
                     </div>
                 </div>
@@ -70,7 +76,9 @@ pub fn OverviewPage() -> impl IntoView {
                                         "🪐"
                                     </div>
                                 </div>
-                                <span class="mt-6 text-lg text-gray-300 animate-pulse">"Loading cosmic data..."</span>
+                                <span class="mt-6 text-lg text-gray-300 animate-pulse">
+                                    {t!(i18n, home.loading)}
+                                </span>
                             </div>
                         }
                     }
@@ -85,13 +93,13 @@ pub fn OverviewPage() -> impl IntoView {
                                 </div>
                             }),
                             Err(err) => {
-                                let error_msg = format!("Error loading data: {}", err);
+                                let error_msg = format!("{}: {err}", t_string!(i18n, home.error_loading));
                                 leptos::either::Either::Right(view! {
                                     <div class="max-w-2xl mx-auto mt-10 bg-red-900/50 border-2 border-red-500 text-red-100 px-6 py-4 rounded-xl backdrop-blur-sm">
                                         <div class="flex items-center gap-3">
                                             <span class="text-2xl">"⚠️"</span>
                                             <div>
-                                                <h3 class="font-semibold text-lg">"Connection Error"</h3>
+                                                <h3 class="font-semibold text-lg">{t!(i18n, home.connection_error)}</h3>
                                                 <p class="text-sm text-red-200">{error_msg}</p>
                                             </div>
                                         </div>
@@ -108,34 +116,35 @@ pub fn OverviewPage() -> impl IntoView {
 
 #[component]
 fn StatsOverview(stats: DataStats) -> impl IntoView {
+    let i18n = use_i18n();
     view! {
         <div class="grid grid-cols-1 md:grid-cols-2 lg:grid-cols-4 gap-6">
             <StatCard
-                title="Stellar Systems"
+                title=t_string!(i18n, home.stellar_systems)
                 value=stats.stellarhosts_total.to_string()
                 icon="⭐"
-                subtitle="Host stars catalogued"
+                subtitle=t_string!(i18n, home.host_stars_catalogued)
                 gradient="from-blue-600 to-cyan-500"
             />
             <StatCard
-                title="Exoplanets"
+                title=t_string!(i18n, home.exoplanets)
                 value=stats.exoplanets_total.to_string()
                 icon="🪐"
-                subtitle="Distinct planets in the catalog"
+                subtitle=t_string!(i18n, home.distinct_planets)
                 gradient="from-purple-600 to-pink-500"
             />
             <StatCard
-                title="Avg Stellar Temp"
+                title=t_string!(i18n, home.average_temperature)
                 value=format!("{:.0} K", stats.avg_stellar_temp)
                 icon="🌡️"
-                subtitle="Mean effective temperature"
+                subtitle=t_string!(i18n, home.mean_temperature)
                 gradient="from-orange-600 to-red-500"
             />
             <StatCard
-                title="Avg Distance"
+                title=t_string!(i18n, home.average_distance)
                 value=format!("{:.1} pc", stats.avg_stellar_distance)
                 icon="📏"
-                subtitle="Mean system distance"
+                subtitle=t_string!(i18n, home.mean_distance)
                 gradient="from-green-600 to-emerald-500"
             />
         </div>
@@ -144,46 +153,47 @@ fn StatsOverview(stats: DataStats) -> impl IntoView {
 
 #[component]
 fn DetailedStats(stats: DataStats) -> impl IntoView {
+    let i18n = use_i18n();
     view! {
         <div class="space-y-6">
             <div class="grid grid-cols-1 lg:grid-cols-2 gap-6 items-start">
                 <StatSection
-                    title="Planet Classifications"
-                    subtitle="Distinct planets grouped by canonical radius"
+                    title=t_string!(i18n, home.planet_classifications)
+                    subtitle=t_string!(i18n, home.planet_classifications_subtitle)
                     icon="🌍"
                     items=stats.planet_size_categories
                 />
                 <StatSection
-                    title="Orbital Periods"
-                    subtitle="Distinct planets grouped by canonical period"
+                    title=t_string!(i18n, home.orbital_periods)
+                    subtitle=t_string!(i18n, home.orbital_periods_subtitle)
                     icon="🌀"
                     items=stats.orbital_period_buckets
                 />
             </div>
             <div class="grid grid-cols-1 lg:grid-cols-2 gap-6 items-start">
                 <StatSection
-                    title="Discovery Methods"
-                    subtitle="Distinct planets grouped by canonical method"
+                    title=t_string!(i18n, home.discovery_methods)
+                    subtitle=t_string!(i18n, home.discovery_methods_subtitle)
                     icon="🔭"
                     items=stats.discovery_methods
                 />
                 <StatSection
-                    title="Discovery Years"
-                    subtitle="Distinct planets grouped by earliest discovery year"
+                    title=t_string!(i18n, home.discovery_years)
+                    subtitle=t_string!(i18n, home.discovery_years_subtitle)
                     icon="📅"
                     items=stats.discovery_years
                 />
             </div>
             <div class="grid grid-cols-1 lg:grid-cols-2 gap-6 items-start">
                 <StatSection
-                    title="Planet Temperature Bands"
-                    subtitle="Distinct planets grouped by canonical equilibrium temperature"
+                    title=t_string!(i18n, home.temperature_bands)
+                    subtitle=t_string!(i18n, home.temperature_bands_subtitle)
                     icon="🌡️"
                     items=stats.planet_temperature_bands
                 />
                 <StatSection
-                    title="Detection Sources"
-                    subtitle="Distinct planets grouped by discovery facility"
+                    title=t_string!(i18n, home.detection_sources)
+                    subtitle=t_string!(i18n, home.detection_sources_subtitle)
                     icon="🛰️"
                     items=stats.detection_sources
                 />
@@ -200,6 +210,7 @@ fn StatCard(
     subtitle: &'static str,
     gradient: &'static str,
 ) -> impl IntoView {
+    let i18n = use_i18n();
     view! {
         <div class="group relative overflow-hidden rounded-2xl bg-slate-800/50 backdrop-blur-sm border border-slate-700 p-6 transition-all duration-300 hover:scale-105 hover:border-slate-500 hover:shadow-2xl hover:shadow-purple-500/20">
             // Gradient overlay
@@ -209,7 +220,7 @@ fn StatCard(
                 <div class="flex items-start justify-between mb-4">
                     <span class="text-5xl filter drop-shadow-lg">{icon}</span>
                     <div class=format!("px-3 py-1 rounded-full bg-gradient-to-r {} text-white text-xs font-bold", gradient)>
-                        "LIVE"
+                        {t!(i18n, home.live)}
                     </div>
                 </div>
 
diff --git a/src/i18n.rs b/src/i18n.rs
new file mode 100644
index 0000000..313d6a3
--- /dev/null
+++ b/src/i18n.rs
@@ -0,0 +1,5 @@
+#![allow(deprecated)]
+
+leptos_i18n::load_locales!();
+
+pub use i18n::*;
diff --git a/src/lib.rs b/src/lib.rs
index e1c0773..feaaae9 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -3,6 +3,8 @@
 pub mod app;
 pub mod components;
 pub mod error_template;
+pub mod i18n;
+pub mod locale;
 pub mod metadata;
 pub mod metadata_helpers;
 pub mod structured_data;
diff --git a/src/locale.rs b/src/locale.rs
new file mode 100644
index 0000000..5d2b0ba
--- /dev/null
+++ b/src/locale.rs
@@ -0,0 +1,115 @@
+use crate::i18n::Locale;
+
+pub const ZH_CN_PREFIX: &str = "/zh-CN";
+pub const JA_PREFIX: &str = "/ja";
+
+pub fn locale_from_path(path: &str) -> Locale {
+    if has_prefix(path, ZH_CN_PREFIX) {
+        Locale::zh_CN
+    } else if has_prefix(path, JA_PREFIX) {
+        Locale::ja
+    } else {
+        Locale::en
+    }
+}
+
+pub fn strip_locale_prefix(path: &str) -> &str {
+    for prefix in [ZH_CN_PREFIX, JA_PREFIX] {
+        if path == prefix {
+            return "/";
+        }
+        if let Some(rest) = path.strip_prefix(prefix)
+            && rest.starts_with('/')
+        {
+            return rest;
+        }
+    }
+    path
+}
+
+pub fn localized_path(path: &str, locale: Locale) -> String {
+    let base = strip_locale_prefix(path);
+    if is_utility_path(base) {
+        return base.to_string();
+    }
+
+    match locale {
+        Locale::en => base.to_string(),
+        Locale::zh_CN => prefix_path(ZH_CN_PREFIX, base),
+        Locale::ja => prefix_path(JA_PREFIX, base),
+    }
+}
+
+pub fn localized_url(
+    pathname: &str,
+    search: &str,
+    hash: &str,
+    locale: Locale,
+) -> String {
+    format!("{}{}{}", localized_path(pathname, locale), search, hash)
+}
+
+pub fn is_utility_path(path: &str) -> bool {
+    path == "/mcp"
+        || path == "/swagger-ui"
+        || path.starts_with("/rest/")
+        || path.starts_with("/swagger-ui/")
+        || path.starts_with("/sitemap-")
+        || path.ends_with(".json")
+        || path.ends_with(".csv")
+}
+
+fn has_prefix(path: &str, prefix: &str) -> bool {
+    path == prefix
+        || path
+            .strip_prefix(prefix)
+            .is_some_and(|rest| rest.starts_with('/'))
+}
+
+fn prefix_path(prefix: &str, path: &str) -> String {
+    if path == "/" || path.is_empty() {
+        prefix.to_string()
+    } else {
+        format!("{prefix}{path}")
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn parses_only_supported_locale_prefixes() {
+        assert_eq!(locale_from_path("/"), Locale::en);
+        assert_eq!(locale_from_path("/zh-CN"), Locale::zh_CN);
+        assert_eq!(locale_from_path("/zh-CN/exoplanets"), Locale::zh_CN);
+        assert_eq!(locale_from_path("/ja/stellarhosts"), Locale::ja);
+        assert_eq!(locale_from_path("/zh-CN-not-a-locale"), Locale::en);
+    }
+
+    #[test]
+    fn switches_locale_and_preserves_url_state() {
+        assert_eq!(
+            localized_url("/ja/exoplanets", "?page=2", "#results", Locale::zh_CN),
+            "/zh-CN/exoplanets?page=2#results"
+        );
+        assert_eq!(
+            localized_url("/zh-CN", "", "#mcp-exoplanet-data", Locale::en),
+            "/#mcp-exoplanet-data"
+        );
+    }
+
+    #[test]
+    fn utility_and_export_paths_remain_unprefixed() {
+        for path in [
+            "/mcp",
+            "/rest/query",
+            "/swagger-ui",
+            "/stellarhosts/TRAPPIST-1.json",
+            "/exoplanets/Kepler-22%20b.csv",
+            "/sitemap-index.xml",
+        ] {
+            assert_eq!(localized_path(path, Locale::ja), path);
+        }
+    }
+}
diff --git a/src/server/handlers.rs b/src/server/handlers.rs
index 6bf2e18..97a71f8 100644
--- a/src/server/handlers.rs
+++ b/src/server/handlers.rs
@@ -340,10 +340,9 @@ fn parse_detail_export_path(
     let (encoded_name, format) =
         if let Some(name) = name_with_suffix.strip_suffix(".json") {
             (name, exports::ExportFormat::Json)
-        } else if let Some(name) = name_with_suffix.strip_suffix(".csv") {
-            (name, exports::ExportFormat::Csv)
         } else {
-            return None;
+            let name = name_with_suffix.strip_suffix(".csv")?;
+            (name, exports::ExportFormat::Csv)
         };
 
     let name = percent_encoding::percent_decode_str(encoded_name)
@@ -760,6 +759,8 @@ pub fn build_sitemaps(
 fn build_static_urls(site_url: &str) -> Vec<String> {
     let mut urls = vec![
         format!("{site_url}/"),
+        format!("{site_url}/zh-CN"),
+        format!("{site_url}/ja"),
         format!("{site_url}/docs"),
         format!("{site_url}/docs/cli"),
         format!("{site_url}/docs/api"),
diff --git a/src/server/tests.rs b/src/server/tests.rs
index 99ba2ed..2d23ca2 100644
--- a/src/server/tests.rs
+++ b/src/server/tests.rs
@@ -542,6 +542,8 @@ mod tests {
 
         assert!(xml.contains("<urlset"));
         assert!(xml.contains("<loc>https://example.com/</loc>"));
+        assert!(xml.contains("<loc>https://example.com/zh-CN</loc>"));
+        assert!(xml.contains("<loc>https://example.com/ja</loc>"));
         assert!(xml.contains("<loc>https://example.com/docs</loc>"));
         assert!(xml.contains("<loc>https://example.com/docs/cli</loc>"));
         assert!(xml.contains("<loc>https://example.com/docs/api</loc>"));
@@ -572,6 +574,8 @@ mod tests {
         assert!(xml.contains("<lastmod>2026-01-15</lastmod>"));
         assert!(!xml.contains("/stellarhosts/"));
         assert!(!xml.contains("/exoplanets/"));
+        assert!(!xml.contains("/zh-CN/stellarhosts"));
+        assert!(!xml.contains("/ja/exoplanets"));
     }
 
     #[tokio::test]
diff --git a/style/components/homepage-manual.css b/style/components/homepage-manual.css
index 52f19dd..38beb62 100644
--- a/style/components/homepage-manual.css
+++ b/style/components/homepage-manual.css
@@ -18,6 +18,10 @@
   @apply mb-4 text-3xl font-semibold text-white md:text-4xl;
 }
 
+.homepage-manual__prose h1 a {
+  @apply inline-block cursor-pointer no-underline transition-colors hover:text-sky-200 focus:rounded-sm focus:outline-none focus:ring-2 focus:ring-sky-400;
+}
+
 .homepage-manual__prose p {
   @apply my-4;
 }
@@ -30,6 +34,10 @@
   @apply text-2xl font-semibold text-white;
 }
 
+.homepage-manual__section-heading h2 a {
+  @apply inline-block cursor-pointer text-white no-underline transition-colors hover:text-sky-200 focus:rounded-sm focus:outline-none focus:ring-2 focus:ring-sky-400;
+}
+
 .homepage-manual__section-heading p {
   @apply text-sm leading-6 text-slate-400;
 }