@yirc99/dsh-jev-context

dsh-jev-context

JEV-scored context selection for DeepSeek Harness.

Every turn pays for the whole conversation. This plugin keeps the model-visible history to the earlier segments a turn actually needs: on each turn's first step it cuts the session surface where each unit of work began, asks the JEV decision service (TypeSafe System One, about one second and $0.04 per million input tokens) for one relevance probability per candidate segment, replaces the irrelevant ones with a one-line omission marker, and recalls a shelved segment when its topic returns.

The log is never edited. A shelved segment stays readable in the session log, so recall re-materializes it, and every decision is recorded as a durable context-jev/turn event that a session projection folds into the sidebar console.

Install

Inside the harness, from the plugin market (Settings → Plugins → Market), or:

dsh plugin --profile web add @yirc99/dsh-jev-context

Then restart dsh web and open the JEV row at the foot of the sidebar. Installing the package is enough: it declares both its configuration layer (cordis.patch.yml) and its browser half, so no second row or manual cordis.yml edit is needed.

Configure

The only required input is an API key. Without one the plugin records a no-key ledger entry per turn and leaves the surface alone.

The key resolves in this order: the apiKey setting, the credential reference named by apiKeyEnv (default TYPESAFE_API_KEY), then the launching environment. The settings namespace is jev-context; apiKey is a role('secret') field, so a remote settings read reports only whether one is stored.

Field	Default	Meaning
enabled	true	Run selection at all.
threshold	0.5	Probability at or above which a segment counts as relevant.
keepRecentSegments	1	Trailing segments never judged.
minSegmentTokens	400	Smallest segment worth rewriting; below it the marker costs about what the segment does.
maxSegmentsPerDecision	40	Largest question set sent in one call.
retainedTurns	12	Ledger records the browser view retains; read at mount.
model, baseURL, timeoutMs, digestChars	jev-1.13.0, the System One base, 20s, 320	Decision service identity and bounds.

What it does to your session log

One thing is worth stating plainly, because it is the only thing this plugin writes that other tools read back.

The ledger event type context-jev/turn is declared by this package, so a harness that does not install the plugin has it outside its generated known-type vocabulary — and such a harness refuses to load a session log containing an unrecognized event it has no reason to trust. The record is therefore appended with the harness's ignorable marker, which states that skipping it cannot change how the rest of the log is read.

That marker is only written by a harness that supports it. On an older harness the plugin detects the gap at mount, logs one warning, and leaves the ledger off rather than storing records your own harness would then refuse to load. Context selection itself is unaffected.

Everything else the plugin does is a normal surface rewrite: a compaction/prune event immediately followed by its replacement, with no yield between them, which is the protocol the harness's own compaction uses. The original bytes stay in the log.

How it works

A segment is a maximal run of surface nodes beginning where the harness recorded a new unit of work — a human prompt, a goal round, or a teammate message. Segmentation reads the current surface, so it survives this plugin's own rewrites: an omission marker and a recall marker are themselves segment starts, and each marker cites the original nodes it shadowed. Filtering marker sequences out of those citations recovers a segment's identity and digest after any number of prune/recall cycles.

Both rewrites ride the shared shadow-price protocol, so the context-pressure projection subtracts the shadowed range's price exactly and the reported saving is the number the meter itself uses. A rewrite is one user/message replacement; assistant/message cannot cite source events, so a recalled segment returns as a role-labelled transcript rather than as its original nodes.

The engine runs on agent/pre-step, before the request is built. Only a turn's first step selects: later steps of one turn share a request prefix, and re-scoring them would churn the surface between two requests that differ only in their tail. Every failure is contained — an unreachable service, a malformed answer set, or a rejected append leaves the surface unchanged, records why, and lets the turn proceed.

Known limitations

• It speaks both session-format generations. The marker messages it injects follow the running harness: kind: 'plugin' with the package name on format 3 and earlier, and this package's own kind: 'jev-context' on format 4, which refuses the shared kind. SESSION_FORMAT_VERSION decides, so a session stays loadable whichever build wrote it. Both generations validate a source against a closed set, which is why the shape cannot be a compile-time constant.
• Features that need a newer build degrade, and say so. The settings panel needs SettingsForms.installSection, and the ledger needs the ignorable write path described above. Where a harness lacks one, the plugin reports it once at mount and runs without that piece; context selection needs neither.
• A rewrite invalidates prompt-cache reuse from the oldest changed segment, so alternating between two topics can cost more in cache misses than the shelved tokens save. Selection is per turn; nothing changes within a turn.
• The decision service is a network dependency on the turn's critical path, bounded by timeoutMs. A failed call costs the turn one round trip and nothing else.
• Relevance comes from segment digests, not full content, so relevance that lives only in a code block or a tool body is invisible to the decision. digestChars widens the window without changing the principle.

Local development

pnpm install
pnpm build          # lib/index.js (Node half) + lib/client.js (browser half)
pnpm typecheck      # against the harness version in devDependencies

Installing a local checkout into a profile copies it: dsh plugin add file:... does not follow later rebuilds, and re-running add reports "already up to date" while the profile keeps the old copy. Remove and add again after a rebuild:

dsh plugin --profile  remove @yirc99/dsh-jev-context
dsh plugin --profile  add file:/absolute/path/to/dsh-jev-context

exports must list ./cordis.patch.yml. A package whose exports map omits it is installed, listed in the profile's bundle stack, and then silently skipped when the profile composes: the row never appears in --dump-config and nothing reports why.

The published package ships JavaScript only. Type declarations would need the harness APIs this plugin is written against to be present in the versions devDependencies pins, and pnpm typecheck reports exactly which of them a given version lacks; until that resolves, types stays out of the manifest rather than pointing at a file the tarball does not contain.

License

MIT