# 18 — Coverage and gap map (https://jackin.tailrocks.com/research/context/techniques/18-extension-overview/) ## Summary [#summary] The core techniques chapters cover text-token economics, caching, retrieval, output discipline, routing, provider features, infrastructure, composition, and validation. This map identifies the decision axes that need separate treatment: subscription quota, multimodal input, latency and human time, fleet behavior, portability, current literature, and runtime governance. The strongest correction is conceptual: a subscriber constrained by a usage cap should optimize **tasks per cap**, not API dollars per task. Multimodal input is another distinct token class rather than a footnote to text context. Latency and quality also need explicit accounting because a cheaper token path can still be slower or less reliable. ## Question and scope [#question-and-scope] Which independent cost and quality axes are already covered, and where do material evidence gaps remain? ## Method [#method] Coverage was assessed against six independent axes rather than the dossier table of contents: | Axis | Decision dimension | | ---------------- | ----------------------------------------------------------------------------------------------- | | Cost metric | dollars, subscription quota, wall-clock time, human attention | | Token class | fresh input, cache write, cache read, visible output, thinking, image, document | | Emission surface | system prefix, tools, message history, model output, media tool results | | Lever | style, tokenizer, context architecture, caching, retrieval, routing, infrastructure, governance | | Scope | turn, session, cross-session, capsule, fleet, organization | | Delivery | instruction, configuration, hook, orchestrator, provider feature | The existing chapters were checked for absent, incidental, partial, or decision-complete treatment. A topic remains a gap when the corpus mentions it but does not supply the measurement or decision rule required to choose an action. ## Findings [#findings] ### Current coverage map [#current-coverage-map] | Topic | Current assessment | Decision stake | Detailed chapter | | -------------------------------- | ---------------------------------------------------------------------------- | ------------------------------------------------------------------------------ | -------------------------------------------------------------------------------------------------------------- | | Subscription and quota economics | Dollar economics are mature; cap accounting remains partly provider-opaque | Cache-heavy levers can rank differently under quota than under API prices | [19 — Subscription and quota economics](/research/context/techniques/19-subscription-and-quota-economics/) | | Multimodal input | Separate measurement required for images, screenshots, and PDFs | A screenshot can be cheaper or much more expensive than structured text | [20 — Multimodal token economics](/research/context/techniques/20-multimodal-token-economics/) | | Latency and human time | Token and dollar models do not decide the time tradeoff | Fan-out, fast modes, and compression hops can exchange tokens for elapsed time | [21 — Latency and time economics](/research/context/techniques/21-latency-and-time-economics/) | | Fleet and multi-tenant caching | Self-host mechanisms are covered; hosted cache scope is not fully observable | Spawn timing, dynamic prefixes, and quota attribution change fleet efficiency | [22 — Fleet and multi-tenant cache](/research/context/techniques/22-fleet-and-multitenant-cache/) | | Cross-agent portability | Individual mechanisms are documented, but support differs by runtime | A stack tied to one hook or provider is fragile | [23 — Portability matrix](/research/context/techniques/23-cross-agent-portability/) | | Literature and product surface | Provider features and research continue to change | New mechanisms can strengthen, qualify, or leave existing decisions unchanged | [24 — Literature and market scan](/research/context/techniques/24-fresh-literature-and-market-delta/) | | Governance and online quality | Offline validation exists; runtime budget and drift controls are thinner | Savings are invalid if measurement overhead or quality regressions erase them | [25 — Governance and online quality](/research/context/techniques/25-meta-cost-governance-and-online-quality/) | | Unresolved mechanisms | Several ideas remain conditional or provider-blocked | Frontier ideas need feasibility gates before entering a stack | [26 — Frontier mechanisms](/research/context/techniques/26-extension-frontier/) | | Combined verdict | Layer interactions and metric choice need one synthesis | Composition must count overlap, cache effects, recovery, and quality | [27 — Stack verdict](/research/context/techniques/27-extension-stacks-and-verdict/) | | Volatile claims | Provider-sensitive claims require an explicit verification contract | A current decision must expose its cutoff and uncertainty | [28 — Provider-sensitive claim verification](/research/context/techniques/28-drift-delta/) | ### Headline findings [#headline-findings] * **Quota is a separate objective.** Provider caps are not transparently convertible to API dollars, so quota-sensitive conclusions are explicitly bounded where the denominator is unpublished. * **Media must be measured in its native representation.** Image and PDF cost depends on dimensions, preprocessing, page handling, and provider rules; text-token intuition is insufficient. * **Latency is not a token subclass.** It belongs beside token and quality metrics in the acceptance function. * **Fleet behavior is cache behavior plus orchestration.** Prefix identity, dynamic sections, start timing, and provider cache scope determine whether nominally identical agents share work. * **Portability follows the interception boundary.** Instruction-only techniques travel widely; provider betas, proprietary hooks, and runtime-specific storage do not. * **Governance is part of net savings.** Measurement, recovery, retries, and quality monitoring consume resources and must be charged to the technique. ## Implications for jackin❯ [#implications-for-jackin] For jackin❯, the coverage and gap map evidence identifies which mechanisms are safe to adopt directly and which still require workload-specific validation. ## Limitations and unknowns [#limitations-and-unknowns] ### Evidence boundaries [#evidence-boundaries] The chapters use the measurement conventions in [01 — Economics and measurement](/research/context/techniques/01-economics-and-measurement/) and the acceptance harness in [16 — Validation harness](/research/context/techniques/16-validation-harness/). Provider-sensitive facts follow the [verification contract](/research/context/techniques/28-drift-delta/). Where providers do not publish quota weights, cache scope, or internal token accounting, the result stays bounded rather than inferred. The dossier's measured heavy-session profile remains a comparison fixture, not a universal workload. Reach must be remeasured for each capsule because a docs-heavy task dominated by native reads presents different optimization opportunities from a shell-heavy code task. ## Sources [#sources] Evidence and repository references are cited inline beside the claims they support. ## Related work [#related-work] * [Executive summary](/research/context/techniques/00-executive-summary/) * [Baseline audit](/research/context/techniques/02-baseline-audit/) * [Composed stacks](/research/context/techniques/15-composed-stacks/) * [Validation harness](/research/context/techniques/16-validation-harness/) * [Adoption roadmap](/research/context/techniques/17-adoption-roadmap/)