com_r35157_nenjim-hubd-impl_ref/openspec/specs/assetaz-ticker-service/spec.md

assetaz-ticker-service Specification

Purpose

Provide AssetAZ callers with typed latest prices backed by explicitly enabled, durable observation histories.

Requirements

Requirement: Price sources are discovered and lifecycle-managed

Nenjim SHALL be able to construct and register each price source independently in an initialized but unstarted state without supplying a ticker or sink. The ticker SHALL receive the public Nenjim Registry through constructor injection and resolve its explicitly configured PriceSource component IDs, while ordinary ticker clients SHALL NOT receive a public operation for adding or managing sources. The ticker SHALL fail clearly when a configured ID is missing or names a component that does not implement PriceSource; it SHALL NOT silently select the first source listed for the interface. The ticker SHALL identify each resolved source by its TradingPair and stable source name, reject duplicate identities clearly, start each active source by passing itself as PriceSink, and stop every source it started. Source names SHALL be non-empty safe directory components and SHALL reject /, \, .., and control characters without rewriting them. A source SHALL announce typed prices and timestamps only through the sink received at start and SHALL remain unaware of its persistence path. A repeated source start SHALL reject the call before replacing its existing sink.

Scenario: Sources are constructed independently

• WHEN the Registry manager constructs and registers a price source before constructing or starting the ticker
• THEN source construction requires neither a PriceSink nor a ticker reference and leaves the source unstarted

Scenario: Ticker resolves configured source components

• WHEN the ticker initializes its source set from explicit component IDs and an injected public Registry
• THEN it resolves each ID as PriceSource, not PriceSink, and manages only the resolved configured sources internally

Scenario: Missing configured source fails clearly

• WHEN the ticker is configured with an absent component ID or an ID whose object is not a PriceSource
• THEN construction fails with a diagnostic identifying the ID and required interface

Scenario: Ordinary clients cannot manage sources

• WHEN a caller uses the public TickerService contract
• THEN the contract exposes ticker lifecycle and latest-price queries but no source-registration operation

Scenario: Distinct configured sources are accepted

• WHEN the ticker resolves two configured sources with different source names or trading pairs
• THEN it accepts both and manages each source independently

Scenario: Duplicate persistent identity is rejected

• WHEN the ticker resolves sources with the same trading pair and source name
• THEN initialization fails with an error identifying the duplicate source history

Scenario: Unsafe source name is rejected

• WHEN a source name is empty or contains a slash, backslash, .., or a control character
• THEN ticker initialization or startup fails clearly without rewriting the source name or creating filesystem content

Scenario: Active source lifecycle is managed

• WHEN the ticker starts and later stops with an active Registry-resolved source
• THEN it calls start with itself as PriceSink and subsequently stops the source without leaving source-owned resources running

Scenario: Repeated source start preserves existing sink

• WHEN an already-started source receives another start call with a different sink
• THEN it rejects the call before replacing the sink from the successful start

Requirement: Ticker exposes typed latest prices

The ticker SHALL expose the latest successfully persisted PriceObservation for a requested TradingPair across all active Registry-resolved sources for that pair. A PriceObservation SHALL contain exactly an AssetPrice, its observation Instant, and the stable source name; the AssetPrice SHALL contain both its ΩPriceΩ value and TradingPair. If several active sources provide a pair, latest SHALL be the observation with the greatest observedAt timestamp, and its source name SHALL identify its source. A request for a pair with no resolved sources, no active sources, or no successfully persisted observation SHALL throw a clear exception rather than return null.

Scenario: Latest supported price is available

• WHEN a caller requests a trading pair after at least one observation has been loaded or persisted by an active source
• THEN the ticker returns the successfully persisted observation with the greatest timestamp and its source identity

Scenario: Newest observation is selected across sources

• WHEN multiple active sources for one trading pair have successfully persisted observations
• THEN the ticker returns the observation with the greatest observedAt across those sources

Scenario: Pair has no resolved or active source

• WHEN a caller requests a pair with no configured Registry-resolved source or whose resolved sources are all inactive
• THEN the ticker throws an exception that clearly identifies the unavailable trading pair

Scenario: Active pair has no persisted observation

• WHEN a caller requests a pair whose active sources have no successfully persisted observation
• THEN the ticker throws an exception that clearly states that no persisted price is available for that trading pair

Requirement: Price history explicitly activates each source

For each configured Registry-resolved source, the ticker SHALL derive an independent history path as data/assetaz/ticker/<base UUID>/<quote UUID>/<source name>/<safe base symbol>_<safe quote symbol>.prices. UUIDs SHALL use their unchanged canonical representation and SHALL be the technical trading-pair identity; sanitized symbols SHALL be used only for the human-readable filename. Only an existing file at that exact path SHALL activate the source. The ticker SHALL neither scan for arbitrary sources nor create or migrate missing files or directories. It SHALL load every valid observation using the resolved source's trading pair and source name and select the greatest timestamp across all active histories for each pair, regardless of file order. Empty lines, full-line comments, and inline comments SHALL remain supported. An existing history with no data SHALL activate only that source without an initial observation, while a missing history SHALL leave only that source inactive and emit a warning containing the trading pair, source name, and complete expected path.

Scenario: Existing source history activates and restores identity

• WHEN a Registry-resolved source has an existing valid history with permitted whitespace or comments
• THEN that source is active and its observations are restored with its captured trading pair and source name

Scenario: Empty source history activates without a price

• WHEN a Registry-resolved source has an existing empty or comment-only history file
• THEN that source is active without an initial observation

Scenario: Missing source history leaves only that source inactive

• WHEN one resolved source history is missing while another source for the same pair has an existing history
• THEN the missing source is not started, the existing source remains active, and no missing path is created

Scenario: Missing history warning identifies the source

• WHEN a Registry-resolved source's expected history file is absent
• THEN the ticker logs a warning containing its trading pair, source name, and complete expected UUID-based path

Scenario: Malformed source history is rejected clearly

• WHEN comment text is removed and a non-empty data line in an active source history lacks a valid UTC timestamp and price
• THEN ticker startup fails with an error containing the history filename, one-based physical line number, and identifying invalid content

Scenario: Legacy history is not migrated

• WHEN only data/assetaz/ticker/EVE_USDC.prices exists
• THEN the ticker does not read, move, copy, or create a replacement for that legacy file

Requirement: History uses the human-editable observation format

Each source history data line SHALL retain the form <UTC timestamp>:<price>, where the timestamp uses uuuuMMddHHmmssSSS'Z' with millisecond precision in UTC. Trading-pair and source identity SHALL come from the Registry-resolved source and its directory context and SHALL NOT be stored in individual data lines. Automatic writes SHALL append plain data lines only and SHALL leave all existing comments and blank lines untouched.

Scenario: Observation is written in the required format

• WHEN any source observation at 2026-08-05T13:15:42.783Z with price 14.85 is persisted
• THEN the appended line is 20260805131542783Z:14.85

Scenario: Identity is not duplicated in data lines

• WHEN an observation is appended to a source history
• THEN its data line contains neither source name nor trading-pair identity

Scenario: Existing operator annotations are preserved

• WHEN the ticker appends an observation to a source history containing comments or blank lines
• THEN those existing lines remain unchanged and the appended observation contains neither a comment nor extra annotation

Requirement: New observations are durable before publication

Only an active source resolved and started by the ticker SHALL be allowed to announce an observation. For each accepted announcement, the ticker SHALL validate the source, typed price, and timestamp; construct an observation with the source's captured trading pair and source name; serialize writes to that source history; append and force the data to persistent storage; and only after persistence succeeds consider it for the trading pair's in-memory latest value. Concurrent callbacks from different sources SHALL neither corrupt nor interleave writes, and readers SHALL never observe an unpersisted price. Every accepted observation SHALL be persisted even when an existing observation has a later timestamp, and latest SHALL change only when the newly persisted timestamp is later. If persistence fails, the ticker SHALL report the trading pair, source, and path clearly and preserve the prior latest observation.

Scenario: Active resolved source observation is persisted

• WHEN an active source started by the ticker announces a valid price and timestamp
• THEN the ticker appends and forces the observation to that source's history before considering it for latest

Scenario: Inactive or unknown source callback is rejected

• WHEN an inactive source or a source not resolved by the ticker announces an observation
• THEN the ticker rejects the callback without persisting or publishing it

Scenario: Future-dated observation remains latest

• WHEN an accepted observation is persisted with a timestamp earlier than the current latest observation across active sources
• THEN the accepted observation remains in its source history and the current later observation remains latest

Scenario: Concurrent source callbacks remain durable

• WHEN active sources announce observations concurrently
• THEN each successful append is a complete non-interleaved history line and latest identifies the greatest successfully persisted timestamp

Scenario: Persistence fails

• WHEN appending or forcing an accepted observation fails
• THEN the failure identifies the trading pair, source, and path, the attempted observation is not published, and the previously persisted latest observation remains available